HVAC problems

zach04trailblazer

Registered Member
Original poster
Jan 21, 2018
38
Florida
Hi to everyone on these forums! I'm new here and I'm hoping to get some advice/help from you all concerning Trailblazer vehicle issues.
I have a 2004 LT Trailblazer with a little over 106,000 miles on it.
I've had issues with the airflow cutting completely off on the 5 mark for at least 2 years.
That problem isn't concerning to me but yesterday when I pressed the frost or a/c button or re-circulation button it does nothing.
I cannot even control if air flows only on the floor, or windshield, or anywhere anymore. Instead, the control knob flows air out of all vents.
I am still able to control how much air flows through up to 4 but that is all that works on the control panel.
So it wasn't until this weekend that I noticed practically every control besides air flow knob doesn't work anymore.
The control panel above this climate control panel works fine for radio and all that.

So far , I've fixed a low beam headlight issue, and cleaned the throttle body to fix idling issues. That's as far as I've gone for "fixing" anything on my vehicle.
I'm willing to learn and apply advice of others even though I'm very limited in knowledge about vehicles in general.
I REALLY appreciate anyone willing to help me and others on these forums!! So thank you for even reading my post :smile:
Today, I spent several hours trying to find possible solutions on Youtube and elsewhere but I couldn't seem to find anything regarding this.
The only video I found that seemed like a start is here:
If you check out the video, the HVAC control panel is the same exact one that I have in my 04 Trailblazer.
Another thing is the guy in the video talks about using the OEM schematics to trace and test each component(wiring,connectors, unit) and I would like to find where I could get these schematics to follow this approach.

Also, what tools do I need to troubleshoot any potential issues in the HVAC system? I have a basic multi-meter and wrench set. What else might I possibly need?
Thanks for reading this and I hope we can find a solution!

Regards,

Zach
 

Mooseman

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Dec 4, 2011
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Signature provided below :smile:
 
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zach04trailblazer

zach04trailblazer

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Original poster
Jan 21, 2018
38
Florida
So I started reading HVAC3 (HVAC Systems-Manual) and it requires a diagnostic scan tool for reading digital trouble codes. What would you guys recommend for a tool that is 100% compatible with gm vehicles? Thanks!
 

Mooseman

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Dec 4, 2011
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Apart from the official GM Tech 2, which a clone is $300+ from China, the next best bet is a Bluetooth OBD adapter and the Car Gauge Pro app on Android.
 

Reprise

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For clarity (and you probably realize this yourself) - you have two issues. GMs are known (IMHO) for losing the high speed on the fan (and sometimes more - I had a '97 Pontiac that lost three of the five, over time.) Most of the time, it's a resistor; sometimes a relay. Relays are pretty easy (plug/play). I think you'll need a soldering tool, if it's a resistor. No, I haven't replaced a resistor, sorry to say, and I think (?) they're located outside of the control head. I know there are a couple of threads on this site referencing replacement.

For the air direction issue, as @Matt mentioned above, an actuator has likely gone south (again, fairly common, although the fan speed issue has been around longer than HVAC actuators have; I've had GMs as far back as the '60s - '70s that lost fan speeds).

There's a link he posted above that details the different actuators, what they do, where they're located, and part #s as well.) Not too difficult to swap old / new - the hard part is accessing some of them (you'll see). You'll want to reset your system afterward, either by pulling the HVAC 'B' fuse in the 2nd row fuse panel, or by disconnecting the battery while you put the replacement(s) in.

Hopefully that gives you a little more to go on without having to find someone with a Tech2 (and it would be expensive to purchase one for this issue alone. If you think you'll be hanging on to the truck for a while (or have other GM vehicles up to about 2012 or so) - it's one of the best tools you can have for the GMT360 platform, as it can do things no other tool can do - even the fancy scanners that run $6-8K (!)

Oh - one last thing that may help - you mentioned 'digital trouble codes' - not sure if the manual HVAC (what you have) contains those. The 'automatic' system is sometimes referenced as the 'digital' one; if that's what the manual is referring to, you won't have to worry about those.

I sometimes get info wrong, so let's see if someone corrects anything from above (e.g.; don't head right out to the garage after reading this!)
 
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zach04trailblazer

zach04trailblazer

Registered Member
Original poster
Jan 21, 2018
38
Florida
Thanks @Mounce @Mooseman @Matt @Reprise ! I want to troubleshoot without assuming a part is bad, replacing it, and then finding out that didn't fix the problem. I understand that typically if x number of people have complained about the same issue x number of times and a solution has been verified by those same x numbers or close then it's very likely that the solution posted or advice given is definitive. When I downloaded the service manuals provided by Mooseman, I was pleased to see a step-by-step diagnostic approach that involved testing to confirm which part was faulty because I'm not a mechanic. However, I realized that it's not possible to follow said manual without the Tech2 tool. So let's say if had a Tech2 or clone, it wouldn't be able to help me diagnose the components/modules regarding the HVAC system?? I don't want to jump the gun so to speak. In the HVAC 3 service manual it shows this (service manual lists this as : HVAC Systems - Manual not Automatic):hvac.png
 

Reprise

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I didn't mean to imply the manual systems *don't* make use of the Tech2. Just that if 'digital codes' were in a separate section (especially if under the 'automatic' version), that you might not get those codes, due to the manual vs. automatic.

Now my curiosity is piqued - I'll look over the HVAC 3 documentation, myself. (some might say I should've done that before posting in the first place)
 
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zach04trailblazer

zach04trailblazer

Registered Member
Original poster
Jan 21, 2018
38
Florida
No problem. If anything, I appreciate you taking time to reply back :smile: I tend to not be specific enough when I'm trying to convey my questions and thoughts on the matter. Regarding the actuators and that post from Matt's response -- I don't even know where to begin to troubleshoot which actuator is at fault (if any). The post : ( https://gmtnation.com/forums/threads/2002-envoy-mode-door-actuator-replacement.2744/ ) seemed like it determined the exact problem already and was a how-to guide to fix. I like there's a diagram of the actuators and where they are located. To me, it seems logical that the "mode actuator" would be the faulty part since I cannot change the direction of airflow. Nor can I turn on A/C or re circulation buttons anymore. Still, unless there's a way confirm 99% it's the problem, I'm leery of attempting this.
 
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Reprise

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Jul 22, 2015
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The A/C and recirc buttons don't engage those functions? I don't think you mentioned that earlier. You might need a new control head (easy enough to find at a local junkyard - but get one from the same year and wheelbase (model doesn't matter - you can put a manual head from an Envoy or Bravada into your TB). But I bet you still have a resistor issue w/ fan '5', and a a mode actuator issue.

Since we're at the point where I'm practically telling you to use the parts 'shotgun', let me step back and see what others have to say.
 
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Mooseman

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Just to fill in on what the Tech 2 can do, it can manually move each actuator and you can read the position it goes to. So if it doesn't move or doesn't go to the commanded position. it's bad. You can also activate modes, fan speeds, anything. You can see button presses if they register and so on. A very powerful tool but the expense may not be worth it just to use once on one vehicle.

Manual and automatic are basically the same except that the automatic has the auto mode and can control fan speed. The manual system still has an electronic component to control the actuators but fan control is manual and is done through a traditional resistor pack whereas the auto system uses an electronic fan speed control.

If buttons aren't registering, I'd replace the control panel first just in case that's the problem. One from a junker, like @Reprise said above, shouldn't be too expensive from a pick-a-part and easy to do. If that's squared away and still not getting modes right, then look at the actuators since those are more difficult and expensive.
 
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Matt

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Dec 2, 2011
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Now that you've provided more info, I'm with @Reprise and @Mooseman, sounds like the control head is done. I had to replace mine as well due to it failing. As was mentioned, make sure you get the same model number of control head (the model is on the back of it) as what's in the truck. I didn't know and got one from an 04 that was reconditioned for a great price...turns out it wouldn't work correctly in mine because the model numbers were different and I had to get another one.
 
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zach04trailblazer

zach04trailblazer

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Original poster
Jan 21, 2018
38
Florida
Great. I'll look around for a control head / control panel / whatever you wanna call it. Regarding the Tech 2, clones are around $300 or less and supposedly work exactly the same as the original if luck is on your side. The reason I do consider possibly getting a clone is due to the number of problems I've had with my 04. Seems like every few months I get an unexpected problem. Probably due to the previous owners neglecting it.
 

Mooseman

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Well, look at it this way. After just a few times using it, it would have saved the cost of having to go to the dealer. And can also cut to the chase real fast. Heck, I've even whorred mine out and made some money scanning for people.
 
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zach04trailblazer

zach04trailblazer

Registered Member
Original poster
Jan 21, 2018
38
Florida
@Mooseman Exactly! I've shelled out diagnostic fees too many times in the past only to find they tell me something obvious. I'm planning to get that part ( HVAC control unit ) this weekend but we shall see as there is only one auto salvage place open weekends. The part online doesn't seem too pricey but I still won't have time until this Saturday to pull apart part of dash and find the part #. If it works I'm planning on recording the process and posting via Youtube. If not, then absolutely buying the Tech 2 clone to determine if any of the actuators are faulty.
 

Matt

Guru
Dec 2, 2011
3,834
Check out Ebay, that's where I got both of mine. Just punch in the part # to the search and you'll get the results. Also, ask the seller to show pics of the lights working...I didn't and only have 2 lights working on mine at the moment.
 
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zach04trailblazer

zach04trailblazer

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Original poster
Jan 21, 2018
38
Florida
Checking in... I went to the only junkyard open today and they didnt have the right part unfortunately. I found on ebay the exact same model # but the serial is different. Attached is the back of my a/c unit. On Ebay, I found this: https://www.ebay.com/itm/03-07-CHEV...Heat-AC-Controller-CJ3-10395426-/391421083752

Look's like that part would match but the serial is different. Will this work as replacement for my part?

I did a quick Google search and found the right part brand new for $116.00. They have a 30 day return policy. Checked with online support and based of model number this will work fine. Going to purchase. Will update you guys after swapping. Stay tuned! :wink:
 

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Mooseman

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As long as it's not brand new requiring programming, you'll be fine.
 

Reprise

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I just checked that link; it's listed at $57 / free shipping. If the OP has ponied up the $116, some sort of remedy may be in order. Even if that means someone buys the 2nd one and the OP returns the 1st one.
 
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zach04trailblazer

zach04trailblazer

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Original poster
Jan 21, 2018
38
Florida
I didn't realize a new one would need to be programmed. The unit I purchased was ACDelco 15-73933 from stockwiseauto.com. It's brand new. The local chevy dealership wanted $270 for a new unit. So if I got this unit, I wouldn't be able to use it until it was programmed? Can a Tech 2 program this? If I order a used unit it doesn't need to be programmed?
 
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Mooseman

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Dec 4, 2011
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Yup. A new unit needs to be programmed. A used one doesn't. Tech 2 can program it with the tis2000 software running on a laptop running XP.
 
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zach04trailblazer

zach04trailblazer

Registered Member
Original poster
Jan 21, 2018
38
Florida
Got my used unit today. Hooked it up and still cannot turn on / off a/c, recirc buttons. Moving the temperature sliders from high to cold makes no difference and the mode doesn't change anything at all. The control head on top of bubble wrap is old unit and one hooked up is new unit. I purchased the "new" unit from ebay as a used unit. The seller advised that it was fully working. What would you recommend next? I'm going to check the wiring schematics
 

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Mathoran

Registered Member
May 3, 2012
48
For the manual unit you don't need to program anything. I replaced mine many years ago due to the lights going out. Several posts here mentioned your actuators. That would be my first suspect. I recently had to change 2 of mine out and while I was getting them installed/adjusted at one point my a/c and recirc buttons stopped working as well. Once actuators were in and reset everything works fine again. I'm no expert but I think if the computer thinks you're in defrost mode it locks out the recirc and a/c buttons.

Maybe try the floor/dash vent mode actuator since its the easiest one to get to. Maybe hold your hand on the actuator while turning the floor/dash knob and see if it clicks or tries to turn. The gears could be stripped or it could be completely dead.

good luck
 
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zach04trailblazer

zach04trailblazer

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Original poster
Jan 21, 2018
38
Florida
At this point, I believe there are only two options: 1.) buy a Tech 2 with antiquated xp laptop or 2.) bring into dealership and pay thousands of dollars. Currently, I have 3 issues with my vehicle being this issue, fan speed 5 doesn't work, and the passengers side headlight not working. My analogy of trying to fix my vehicle is like an 80 year old trying to learn how to use a computer. I'm going to keep trying to figure it out but damn it's frustrating. Thanks everyone for your input!
 

Mooseman

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Ottawa, ON
Fan speed issue could be your resistor pack and relay. But that shouldn't affect the buttons. Going over the schematics might reveal something, like a common wire that could be broke.
 
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zach04trailblazer

zach04trailblazer

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Original poster
Jan 21, 2018
38
Florida
Fan speed issue could be your resistor pack and relay. But that shouldn't affect the buttons. Going over the schematics might reveal something, like a common wire that could be broke.

@Mooseman do the service manuals include a legend or symbols for the wiring diagrams? I haven't found any.I'm trying to understand what certain symbols are. The diagram I'm looking at shows that the "High" (speed 5) orange wire from "HVAC Control Module" connects to terminal "A" on the "Blower Motor Relay" and directly below that it passes through a small rectangular symbol. I'm assuming that is the resistor?

I've verified that there is 12v power on the orange wire connecting to "Blower Motor Resistor Assembly" . I'm assuming to test the relay and resistor (if that's what the rectangular symbol is), I have to verify there is 12v power on the purple wire from the "Blower Motor Relay".
 

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budwich

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Jun 16, 2013
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kanata
in "high", the connection that you mention is going to the coil of the relay to operate it... this causes full power to go to the motor. In "non high", the relay is NOT operated and the system reduces the voltage going thru to the motor by selecting different resistor levels as shown. Hence, you need to check that the relay operates in high and that it conducts 12v thru to the motor.
 

Mooseman

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If you look at this one, if you mean the red box, that is the complete resistor pack and forms part of it. The blue box within it is the relay itself and forms part of the resistor pack. The LO-M1-M2-M3 are resistors.
Everything inside the red box is non replaceable.

When you select speed 5, it activates the relay and that would send full 12V to the blower motor.


Resistor pack.jpg

To test, you would put the selector to speeds 1-4 and check at connectors B-A-D-C in that order for +12V. On speed 5, check, check at connector F for +12V. If any are not sending +12V, something is not right coming from the module.

If that checks out, at the Black and Purple wires going to the blower, power should go from lower to higher as you move through the different speed settings. If just some of those are missing, then your resistor pack is faulty.
 
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zach04trailblazer

zach04trailblazer

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Original poster
Jan 21, 2018
38
Florida
Okay, checking now. Thanks for clarifying @budwich @Mooseman

Checked B-A-D-C and none of them got +12V. I used a T-pin inserted into each of those wires and had vehicle in accessory mode.
B in speed 1 = 4.71
A in speed 2 = 6.60
C in speed 3 = 6.92
D in speed 4 = 5.06
I checked F last night it was reading 11.9 and today it was reading different values like 7 or 9

One other thing, I did something wrong because after testing all those wires and removing the t-pin, now the vehicle wont start. I can hear it crank but thats all. Going to wait 20 minutes then will try starting again.

*UPDATE*

Found out the battery was a goner. Had it tested at 2 different places and both times it was bad. Replaced with new battery and car starts again whew. Rechecked connector F and it got 11.6. When I hooked a T-pin to the purple wire and tested on speeds 1-5 I got absolutely nothing. I had the multi meter grounded to nearby metal that I used as well for when I was checking BACD connectors.

*UPDATE 2*

I ordered a power probe 3 today. I'll be getting it this Wednesday or Thursday. This will allow me to take the "Blower Motor Resistor Assembly" out and test to 100% verify if its working.
 

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Chickenhawk

Hobbyist
Dec 6, 2011
715
Why not just buy a new blower motor resistor instead of a new multimeter? In my opinion, you are way overthinking this problem. Answers were provided very early on in this thread. In my opinion, one needs to look at the most common problems first, then the rare ones. The control head has failed, but very very rare. On the other hand, most of us have replaced a blower motor resistor. (Some of us have replaced it two or three over the lifetime of our trucks.) Instead of wasting more time, just replace it. It will fix speed 5.

As for airflow problems, here is likely what has happened. When your battery is marginal, voltage drops below a certain point and it is almost like disconnecting the battery to the HVAC. Your system has probably tried to reset the actuators several times over the past few weeks. To reset the actuators, it needs to find the end readings, so it cranks each actuator all the way until it physically stops in one direction, and then the other. This is what strips the gears. You have probably stripped the gears on at least one actuator, and maybe more. Check the one going to defrost first because, as Matharon points out, if it thinks it is in defrost mode, it might lock out the air and recirc button.

Some of us lose marginal actuators when we replace the battery. You probably had so many voltage drops the past few weeks with a bad battery that it might have stripped gears on several of your actuators.

So don't spend any more money until you look at the likeliest and most common problems first.
1 - Replace the battery
2 - Replace the blower motor resistor
3 - Once the new battery is in, find a very quiet place, turn off the radio, move ALL your HVAC controls to the left, fan off, heat low and turn the ignition to ON (not start). Listen very carefully. Each actuator will run the full length one way, then the other. Sometimes they start buzzing a bit. Just sit and listen until all is silent. It may take 2 to 3 minutes. If you hear one buzzing and it does not go away in 3 minutes (be patient) it is the one that needs replacing. If you hear one not making any sound at all, the gears are probably stripped completely. Now, before you turn anything else on, cycle through the mode settings, from VENT to HEAT to DEFROST. You should hear the actuators cycle as you change the mode. If you DON'T hear an actuator cycle when you change modes, it is also probably the bad one. You need to listen carefully, in a very quiet place, with nothing else on.

Report what you hear here, and someone will be able to help you on replacing that actuator.

If you have already replaced the battery, pull the HVAC fuse for a minute and then perform step 3 above. Listen and report. Don't spend any more money until you have replaced the resistor, battery and narrowed down what actuator is bad.

Hopefully, this works. If not, then start looking at the wiring or things like the control head.
 
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zach04trailblazer

zach04trailblazer

Registered Member
Original poster
Jan 21, 2018
38
Florida
Why not just buy a new blower motor resistor instead of a new multimeter? In my opinion, you are way overthinking this problem. Answers were provided very early on in this thread. In my opinion, one needs to look at the most common problems first, then the rare ones. The control head has failed, but very very rare. On the other hand, most of us have replaced a blower motor resistor. (Some of us have replaced it two or three over the lifetime of our trucks.) Instead of wasting more time, just replace it. It will fix speed 5.

As for airflow problems, here is likely what has happened. When your battery is marginal, voltage drops below a certain point and it is almost like disconnecting the battery to the HVAC. Your system has probably tried to reset the actuators several times over the past few weeks. To reset the actuators, it needs to find the end readings, so it cranks each actuator all the way until it physically stops in one direction, and then the other. This is what strips the gears. You have probably stripped the gears on at least one actuator, and maybe more. Check the one going to defrost first because, as Matharon points out, if it thinks it is in defrost mode, it might lock out the air and recirc button.

Some of us lose marginal actuators when we replace the battery. You probably had so many voltage drops the past few weeks with a bad battery that it might have stripped gears on several of your actuators.

So don't spend any more money until you look at the likeliest and most common problems first.
1 - Replace the battery
2 - Replace the blower motor resistor
3 - Once the new battery is in, find a very quiet place, turn off the radio, move ALL your HVAC controls to the left, fan off, heat low and turn the ignition to ON (not start). Listen very carefully. Each actuator will run the full length one way, then the other. Sometimes they start buzzing a bit. Just sit and listen until all is silent. It may take 2 to 3 minutes. If you hear one buzzing and it does not go away in 3 minutes (be patient) it is the one that needs replacing. If you hear one not making any sound at all, the gears are probably stripped completely. Now, before you turn anything else on, cycle through the mode settings, from VENT to HEAT to DEFROST. You should hear the actuators cycle as you change the mode. If you DON'T hear an actuator cycle when you change modes, it is also probably the bad one. You need to listen carefully, in a very quiet place, with nothing else on.

Report what you hear here, and someone will be able to help you on replacing that actuator.

If you have already replaced the battery, pull the HVAC fuse for a minute and then perform step 3 above. Listen and report. Don't spend any more money until you have replaced the resistor, battery and narrowed down what actuator is bad.

Hopefully, this works. If not, then start looking at the wiring or things like the control head.

First, thank you @Chickenhawk for your input :smile: I do appreciate it. In fact, I'm very grateful for everyone's responses thus far especially @Mooseman who has replied time and time again to this post. Wow, he really likes helping people! I have indeed replaced my battery today and I'll try what you mentioned. It does seem strange to me though that any of the actuators could affect every single control on the control head besides the fan speed.
 

Chickenhawk

Hobbyist
Dec 6, 2011
715
Yes, they do, strangely enough. And you are correct; there are a lot of great and helpful people on this forum. What I suggest you do now is to pull the HVAC fuse as if you had just changed the battery and then plug it back in. This will force a reset of the actuators on the next key start. then go through the procedure in 3 above. Make sure you are in a quiet place and don't have anything running including the fan. Turn the key all the way to the run position (but not start) and then just sit back and listen to them reset themselves. It is actually quite entertaining to hear the whirring. Sometimes they buzz too, which is not a good sign, but keep your fingers crossed that the buzzing stops in 2 to 3 minutes. If you are adventurous, you can even get near the dash and listen to hear which ones DON'T whirr.

By the way, these platforms are heavily dependent on a good battery and you will find a lot of issues are solved with a new battery. If you find it runs rough for a few days and stalls out, especially when the HVAC is running, it is a sign you need to clean your throttle body, as I am sure you have already been told.

The blower motor resistor will likely fix up that fan speed issue too, if a new battery didn't solve it.
 
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zach04trailblazer

zach04trailblazer

Registered Member
Original poster
Jan 21, 2018
38
Florida
Tonight, I pulled all the HVAC fuses in the 2nd fuse box and waited at least one minute. Turned key to accessory. Immediately heard a noise that continued until I removed the key. The noise sounded like it originated from below glove box. Not sure if it was whirring or buzzing. Hard to describe the noise I heard. I recorded the entire session ( 5+ ). I tried to attach but this site doesn't allow .m4a files. So I uploaded the most pertinent part of it to Youtube. Here's the link:
. The only other noise I heard briefly was from the dash and it sounded like the actuator calibrated for maybe 5-8 seconds and went away. When I tried moving the fan mode to different positions no changes in noise occurred. Tried pressing the a/c and defrost and again no changes. Fan speed was at 0 and temp sliders were positioned at bottom.
 

Chickenhawk

Hobbyist
Dec 6, 2011
715
Sounds like you have at least one bad actuator; maybe more. The good ones run for 5 to 8 seconds and they are reset. The bad ones can run constantly because they never get reset properly. If they are all good, you will hear at least one of them whirr quietly for about a second as you change from vent to floor to defrost.

Having a bad battery is hard on actuators because every time the voltage drops below a certain level, they try to reset themselves. This means they use the full travel of their gears, and this is what strips a marginal actuator. The gears just get plain old. If the voltage drops even further, you may find that you have had to reset your clock. (FM stations stay in a non-volatile part of memory however.) But the voltage to keep the clock working is far less than the voltage needed to prevent a reset of the HVAC.

As for diagnosing further and perhaps replacing the bad ones, I will have to leave that to the members with far more experience than me. I have been lucky and never had to replace one. (Yet.)
 

Matt

Guru
Dec 2, 2011
3,834
To see which ones under the drivers side are/aren't working get under there and put a hand on them at start up. The noise under/near the glovebox could be the passenger temp actuator as that's pretty much beside the glovebox.
 
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zach04trailblazer

zach04trailblazer

Registered Member
Original poster
Jan 21, 2018
38
Florida
Replaced blower resistor pack and fan speed 5 works again :2thumbsup:
Thanks guys! Credit goes to all of you!
Last issue to resolve is the HVAC mode controls ( directional fan control, / a/c engage, re-circulation engage )
So the replacement control head I bought awhile back has issues with the lighting. I'm sending it back and getting another unit from same seller on Ebay. Talked with them and supposedly it's a common issue. I wonder if getting a new unit instead of used would fix my a/c & re-circulation problem.
I'll work on the actuators this weekend. This is definitely going to be the most difficult issue I've faced.
 

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Reprise

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Replaced blower resistor pack and fan speed 5 works again :2thumbsup:
Thanks guys! Credit goes to all of you!

See? :Banghead: :deadhorse: LOL :dielaugh:

If you can, replace the actuator(s) first - as @Chickenhawk mentioned in post #32 - you may save yourself having to replace the control head.
The fact that the 'new' one didn't give you back the functionality of those buttons - would further suggest attacking via the actuators, first, IMO.

Also...Props to @Mooseman and May03LT (wherever he is these days) for the diagram & video, respectively, going over how the resistor pack / relay worked & how to troubleshoot. I can finally say - 30 years later -that I understand how GMs fan controls operate now. LMAO
 
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Mooseman

Master Blaster
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Dec 4, 2011
21,832
Ottawa, ON
Burnt out lights in modules and gauges is very common. Doesn't affect operation, just annoying. Most of us just take them apart and replace with LED's except the manual ones are a PITA to take apart because of those slide knobs.

Getting a new one would probably not be any better since you would have to take it to a dealer or someone with a Tech 2 to program it. These are not high failure items but not unheard of. If mode isn't working and two different control heads didn't fix it, likely it's the actuator. The A/C not lighting might be either because it's too cold or the system is inoperative because it's empty of refrigerant (but not sure of that).
 
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