HVAC calibration issue

[syc0path]

I came to this forum after some1 from another site sent me here to get help w/ the Tech 2. I have a 2007 Grand Prix with little or no heat in the passenger cabin. I've done all the basic diagnostics -- low coolant level, plugged heater core, actuator, heater controls, calibration reset, etc, and ruled all of that out. I've traced the problem down to a calibration issue between the commanded position of the blend door actuator (called the "air inlet door" in the Tech 2 menus).

I'm getting some seriously weird readings from the Tech 2. Initially, it shows both the commanded and actual positions as 0 counts. So I used the "Increase" soft key to increase the commanded position by 10%. When I did this, the commanded count stayed at 0 while the actual count went to 910. I increased to 20% and got 0 for both counts. 30%-60% remained the same, but 70% went to 0 and 910. 80% was 0, 0, 90% was 0, 910, and 100% was 0, 0. Why did the commanded position always remain at 0 even though the Tech 2 increased it? Why did the actual position jump between 0 and 910 at random settings?

As I mentioned, I did the actuator calibration reset procedure, which involves pulling and reinstalling the HVAC fuse while the ignition is on. I've done it several times in fact. What I figured out is that when the fuse is first reinstalled, the actuator closes all the way. So I removed the fuse right at that point, leaving the actuator stuck there. Then I turned the ignition off and reinstalled the fuse. After that, I had heat for a couple weeks. It seems like I somehow fooled the BCM enough to (mostly) counteract its incorrect settings. Then it got cold again, so I did it again. It worked for a couple more weeks. But now it's not working, I have no heat at all, and the recalibration trick doesn't seem to work anymore.

Is the Tech 2 capable of resetting/recalibrating/reflashing the BCM and/or the actuator? I've been reading thru many of the threads and I haven't found anything about flashing the BCM.

 

[mrrsm]

Welcome to GMT Nation...

The BCM and PCM Units are Modules like all of the other Modules residing on the GM Class 2 Network. Dr. Shock shows How to Re-Calibrate Modules using JUST the Tech 2 and your Laptop running the TIS2000 Software:

Alternatively, using the ACDelco On Line PASS-THRU Subscription Services (Modest Yearly Fees) you can SELECT the BCM from a Full List of Modules and Re-Calibrate the Unit. However, you may need to have your VIN handy and 'Written Legibly and Large' nearby if prompted to associate the BCM to the PCM at any point during the Re-FLASH using the exact VIN of your vehicle.

This video comes 'Straight from The Horse's Mouth' courtesy AC-Delco using their On-Line TECH2WIN System and while the VOP (Video Original Poster) is using a J- 2534 Unit as his choice of PASS-THRU Device during the On-Line setup of the procedures to update the Module(s), in your case, you would instead use your Laptop Tech 2 SPS Software and choose the TECH 2 from the Hardware Selection Menu. This Instructional shows the Step By Steps to follow to Re-Calibrate and Re-Program ANY Module selected from the Modules Menu after the choice of Vehicle Year-Make-Model steps have been completed.

By Downloading and playing these Videos at 1/2 Speed... you can make some Notes on how to use your TIS2000 Laptop to communicate through your Tech 2 using it as a PASS-THRU Device and the transitions from screen to screen. To avoid any problems of Communication between the Laptop and the Modules involved, please remember to ensure that your SUV Battery is Fully Charged and that your Laptop has a Freshly Charged Battery with an independent source of Power from your Laptop A/C Battery Charger before attempting any Re-FLASH Procedures.

 

[Mooseman]

Just for a recalibration, you shouldn't need to reprogram a module.

Sounds like the actuator is defective and either not moving to the correct position as commanded or the sensor inside it bad.

The Tech 2 should be able to do the recalibration but I've never used it for that, opting for the pull the fuse method. BTW, on our platform, we pull the fuse for a minute and re-install it while the ignition is OFF, which may be different that on your car.

 

[syc0path]

The BCM and PCM Units are Modules like all of the other Modules residing on the GM Class 2 Network. Dr. Shock shows How to Re-Calibrate Modules using JUST the Tech 2 and your Laptop running the TIS2000 Software

Good to know... unfortunately, as I posted on another thread, I still haven't gotten the TIS2000 software working yet.

Just for a recalibration, you shouldn't need to reprogram a module.

Sounds like the actuator is defective and either not moving to the correct position as commanded or the sensor inside it bad.

The Tech 2 should be able to do the recalibration but I've never used it for that, opting for the pull the fuse method. BTW, on our platform, we pull the fuse for a minute and re-install it while the ignition is OFF, which may be different that on your car.

I haven't seen any options to recalibrate w/ the Tech 2, but I agree that it should have that function. Any1 know how to actually do it??

As for the actuator, I've replaced it and it didn't make any difference. And keep in mind that the Tech 2 shows that the commanded position always remains at 0. If the actuator was bad, it seems like the commanded position would change but the actual position would not.

And you're right about pulling the fuse. I did it that way initially but it didn't work. So I tried different variations and eventually hit on the combination that did produce some heat for a while. But not anymore, unfortunately. The ambient temp was 10°F when I left this morning. When I got to work 35 mins later, I could still see my breath in the car.

 

[Maverick6587]

Here's the calibration steps for a 2004 Grand Prix. It should be the same for a 2007.

Use the following steps to perform the calibration update:

1. Turn OFF the ignition.
2. Remove the battery positive voltage circuit fuse of the HVAC Control Module.

Important: The module memory will not clear if the battery positive voltage circuit fuse is installed in less than 60 seconds.

3. Wait 60 seconds.
4. Install the fuse.
5. Start the vehicle
6. Wait 60 seconds before moving the HVAC controls.

I would wait 2 minutes before you start touching any of the HVAC controls.

 

[Mooseman]

Have you tried disconnecting the battery? It's possible that the fuse pull alone is not enough. Try that for 30+ minutes.

It's possible that the HVAC module is defective. Maybe try and pick one up from a pick-n-pull and swap it out. If it's the same year and model, it shouldn't need reprogramming. That or the wiring to the actuator is at fault.

As a temporary workaround, if you can get it to go into heat at all during recal or whatever, unplug the actuator when it's at the heat position when you need to use the car.

 

[syc0path]

Here's the calibration steps for a 2004 Grand Prix. It should be the same for a 2007.

Yes, those are the steps I used when I 1st started trying the recalibration procedure. But just to be thorough, I tried them again exactly as u posted them and it still didn't work.

Have you tried disconnecting the battery? It's possible that the fuse pull alone is not enough. Try that for 30+ minutes.

It's possible that the HVAC module is defective. Maybe try and pick one up from a pick-n-pull and swap it out. If it's the same year and model, it shouldn't need reprogramming. That or the wiring to the actuator is at fault.

As a temporary workaround, if you can get it to go into heat at all during recal or whatever, unplug the actuator when it's at the heat position when you need to use the car.

I thought about disconnecting the battery, but will that reset the BCM's memory? It seems like those numbers would be in the PROM and therefore clearing them would require reflashing the BCM... and I would need to get the Tech 2 working right to do that.

I've replaced the HVAC module with a new unit, and that didn't change anything. I don't think the wiring to the actuator is the issue -- the actuator always moves when it's supposed to. It just doesn't move WHERE it's supposed to!

It seems like I no longer have heat when pulling the fuse during the recal procedure. And unfortunately I can't reach the wiring to unplug the actuator when it's installed. But I could try this... pull the fuse during the recal procedure while the actuator is all the way closed. Leave the fuse out and remove the actuator. Unplug it and reinstall, and then reinstall the fuse. Then I would have the blower fan and mode functions while keeping the actuator in the closed position. Of course, all that would be a PITA, and I would have to undo it when the weather gets warm. Speaking of which, it's supposed to be in the 50's for the next couple weeks, so I'll hold off doing this and hope that another solution is figured out in the meantime.

 

[Maverick6587]

Did you replace the HVAC module and actuator with OEM (ACDelco/Bosch/Delphi) parts?
Were they new or used? If it was used you would have needed to have the actuator drive gear in a certain position.

I'll try to find the thread that details that gear's position.
Edit: found it> https://gmtnation.com/forums/threads/hvac-actuator-noise.19130/post-569144

 

[syc0path]

The actuator was a new Delco part. It had no effect.

 

[syc0path]

I was playing around w/ the Tech 2 last night and learned a few things. This may already be widely known info, but it's new to me. There are 2 relevant menus (Data Display and Special Functions) that basically look the same, but have an important distinction.

Data Display shows the data transferred back and forth between the controls and the actuators. So if u turn a knob on the HVAC controls, u can see both the commanded and actual position readings change accordingly.

When the Special Functions menu is accessed, commands from the HVAC controls are disregarded. Instead, the Tech 2 is used input commands.

This became relevant last night, when I was in the Data Display menu and realized that Air Inlet Door is NOT the blend door. Instead, it's the recirculation door, and it changes position in response to hitting the recirc button. Adjusting the temp control has no effect. What's really, REALLY confusing is that in the Special Functions menu, F1 is the Air Inlet Door and F6 is the Recirc. LED. So they actually use 2 different names for the same item in the SAME MENU😡 That's what led me to believe that the Air Inlet Door must be the blend door. But I know now that the Air Inlet Door should be called the Recirc Door.

What's even more insane to me is that there doesn't seem to be any mention of the blend door!! If it's not the Air Inlet Door, then WTF is it?? I've identified the function of every item listed in the menu. There just doesn't seem to be anything that corresponds to the blend door.

 

[Maverick6587]

Which actuator did you replace and do you have the part number and the location from which you replaced in your car?

With your realization of the naming that ACD and/or the Tech2 uses for the actuators. I'm not sure which actuator you replaced. I assume you replaced a blend door but, do you have a dual climate system in your car and is it automatic or manual temp control?

 

[syc0path]

I have the basic manual, single zone HVAC system. I used AC Delco part# 1574122 from RockAuto, which apparently has been replaced by part# 22754988. I've been using the diagram from here. I replaced Item 12.

I also found a Youtube video , but that was a car with dual-zone climate control. So I only have 1 actuator in that location, and that's the 1 I replaced. Also, the actuators usually make a clicking noise when they fail, and I've never had that.

 

[Maverick6587]

Can you remove the blend door actuator (leaving the connector to the actuator plugged in) to move the blend door control shaft with your fingers? Then turn the heat on from the hvac control module and turn the blend door shaft to see where that shaft needs to be in place for the blend door to push heat out of the vents.

With the heat on and the door in the correct position that heat is coming out of the vents. I would assume the blend door actuator would stop searching for a door position. If that works then just

 

[syc0path]

When I replaced the actuator, I tried turning the shaft w/ my fingers but I couldn't. The shaft doesn't stick out very far so there isn't much to grab. But keep in mind that I've basically already done what u'r suggesting by pulling the fuse during the recal procedure. It works for a while until the computer (incorrectly) recalibrates again.

Another similar idea I've been toying around w/ is to cut the plug out of another car and wire it up to my car with a switch. Then I could manually control the actuator. If I don't get this fixed before next winter, that's probably what I'll do.

 

[Maverick6587]

I would say you either have a problem with your BCM or the HVAC control module then. Did you replace the HVAC control module with a new ACD module?

 

[syc0path]

Did you replace the HVAC control module with a new ACD module?

Yes, I was able to find 1 on RockAuto. It didn't make any difference.

 

[Maverick6587]

Do do you have the Candi module and TIS2000 installed on a Windows xp computer or virtual box for the Tech 2?

 

[syc0path]

Yes... I used southsidesmoka's guide, V1.3. However, I'm having an issue getting the Tech 2 to connect to the PC... see my post in this thread

 

[Maverick6587]

I had similar issues. Did you try switching your USB to serial adapter to the Tripp Lite Keyspan High-Speed USB to Serial Adapter, PC & Mac (USA-19HS)?

 

[syc0path]

Sorry, my previous post was inaccurate. The problem I'm having is w/ the security key not allowing my PC to connect to the server. As far as I can tell, the Tech 2 is properly connected to the PC. I used an adapter with the proper chipset as recommended in the guide.

 

[Mooseman]

Ah well then, you need to install the crack. Full instructions and download links are here:
Computer and Tis2000 setup for Tech2

 

[syc0path]

That's different than the crack that southsidesmoka provided, so I'll give it a try... thanks!

 

[syc0path]

I tried the crack last night, but I kept getting a registry access error. My 1st thought was that I didn't have sufficient permissions, but the user account I set up should have full admin rights. I right-clicked and tried to run install it under the default admin account, but I didn't know the password. Although, now that I think about it, I think the default admin password is "password". Does that sound right? My WinXP skills are a little rusty!

In other developments, I searched the Tech 2 Paths document to find anything that might be related to the blend door actuator, recalibration, etc. I found about 10 potential paths. But when I hooked up the Tech 2 to my car, none of those paths were available.

For example, I tried HVAC Recalibration – Body > Heating and Air Conditioning > Special
Functions > Output Control > Miscellaneous Test. But when I got to the Special Functions menu, there was no Output Control option. I had similar issues w/ every other path I tried.

This leads me back to the same issue I raised in post #10 -- it seems like the blend door actuator isn't even accessible to the Tech 2 for some reason. So even if I get the crack to work, it won't make any difference if I can't actually adjust or reset the blend door.

 

[Mooseman]

You shouldn't need the crack to Tis2000 to access ordinary functions and tests in the Tech 2 itself. You only need it if you are reprogramming/flashing a module or need security access, for example, to relearn a new VATS module, key chip or sensor.

The admin password in XP is whatever you set it to during the install and it asks you to set it for the main admin account. And it's normally hidden from the login screen and have to enable it. It's been a while since I setup mine but I don't remember difficulties writing to the registry.

Unfortunately, we may be at an impasse unless someone has a Tech 2 AND a Grand Prix to try it himself. I know for the GMT's, I can access actuators and command them manually with the Tech 2.

 

[syc0path]

You shouldn't need the crack to Tis2000 to access ordinary functions and tests in the Tech 2 itself.

Yeah, that was my point... if the blend door actuator isn't even listed in the Tech 2 functions, then it doesn't matter if I get the crack to work or not.

Unfortunately, we may be at an impasse unless someone has a Tech 2 AND a Grand Prix to try it himself. I know for the GMT's, I can access actuators and command them manually with the Tech 2.

Not only that, but I suspect that it would also have to be a base model GP. My car is very basic -- base motor, no dual-zone climate control, no heated seats, no ABS/traction control, no foglights, etc. It stands to reason that a higher-trim-level GP that had these options would also have more sophisticated modules/programming.

But if the BCM doesn't control the blend door actuator, then what does? I suppose the temp knob could a simple potentinometer or rheostat that directly controls the actuator's position, but in that case, replacing the HVAC control module should have fixed the issue.

Or could it be that the BCM does in fact control the blend door actuator, but due to a programming limitation, it's just not accessible by the Tech 2? In that case, the best solution would be reflash the BCM. And for that, I would need to be able to get the Tech 2 connected to my PC. At this point, figuring out the registry/permissions issue seems to be my only hope.

 

[Mooseman]

I would imagine that by 2007, all of GM's vehicles use the same type of architecture for HVAC controls, meaning a separate module for each system. If you can get a hold of a repair manual, it would confirm this. At worse, the BCM controls it.

 

[mrrsm]

...

2007 Pontiac Gran Prix HVAC Exploded Parts Diagram:

 

[syc0path]

I think the BCM controls the HVAC system for all GM vehicles of the era, and the actual BCM module itself (the hardware) is probably the same across those vehicles as well. But the software would have to be different -- obviously a car w/ dual-zone automatic-temp HVAC controls will require more sophisticated programming than my single-zone manual-temp setup. And my best guess at this point is that whatever software build is in my car lacks the option for the Tech 2 to access the blend door actuator. I'm also speculating that each GM division is responsible for their own programming, and that Pontiac's tends to be pretty bare-bones.

My parents have '06 and '10 Impalas. The '06 is single-zone manual like mine, while the '10 is dual-zone manual. I'm gonna hook up the Tech 2 to those vehicles and see what options are available in the menus. I suspect that many of the options I was looking for on my GP will be available on the Impalas.

 

[mrrsm]

Have you sourced-priced out getting New ACDelco OEM Blend Door Actuators...JIK the problem is Mechanical?

 

[syc0path]

Have you sourced-priced out getting New ACDelco OEM Blend Door Actuators...JIK the problem is Mechanical?

Yes, I already replaced the actuator w/ a new ACDelco part.

Anyway, I hooked up the Tech 2 to my dad's '06 Impala, and hey, it actually had the commands I was looking for! U can command the blend door, recalibrate all the actuators, etc. Those commands simply don't exist in the programming for my car. So I'm back to trying to reflash the BCM as my only remaining option.

 

[syc0path]

I completely uninstalled the virtual machine on my computer and did a complete fresh install. I applied the crack and was able to access SPS. I linked the Tech 2 to my car and then connected it to my PC, I put in my info and... "Service programming is not supported on this module." 😡 It's enough to make me want to punch something.

I saw something in SPS about a VCI number supplied by the Customer Support Center. It looks like it's some custom programming that is requested by a dealer to fix a customer vehicle. Any1 know how to access this or if it's even possible if service programming is not supported?

Failing that, my next step is to get a wiring pigtail to plug into the actuator so I can hook it up to a momentary switch on a 12V source. Then I can manually control the position of the actuator. I probably should have done this in the 1st place. But the junkyards around me are all shut down, and the part is $45 on Amazon!!! It's just a little plastic plug w/ 2 wires coming out of it! Since the weather is getting warmer and I'm barely driving anywhere anyway, I'll just wait...

 

[syc0path]

As I mentioned in earlier posts, I held off on this all summer. But a couple weeks ago, it started getting colder. Meanwhile the junkyards opened up, so I grabbed an actuator pigtail. I hooked it up to a momentary DPDT switch (think power window switch) in my car and... no heat

At this point, the only thing I could think of was that the blend door much be jammed or obstructed somehow. In fact, I thought the foam on the blend door might have come loose and fallen on the heater core, insulating it from the rest of the vent system regardless of the blend door position.

I thought the only way to fix that is to remove the entire dash assembly right down to the firewall. Knowing what a bitch that job would be, I decided to go back to the junkyard and tear down a car there. I wouldn't have to worry about breaking anything or putting it back together, and I hoped that it would provide me w/ some insight. And if nothing else, it would help me learn how to tear down my own car.

It was a good decision, becuz I learned that I could access the blend door just by pulling out the heater core, which is a MUCH easier job. I wouldn't be able to replace the blend door, but 1) I would know if it needed replacing, and 2) I could remove the foam or any other obstruction.

Also, the 1st heater core in my car failed at about 100k miles, and the 2nd heater core had about the same mileage. I figured I should replace it while I was in there, so I ordered a new part. That was another good decision. Turns out the old heater core was plugged! BUT, that was NOT the whole problem. Keep in mind that I had heat temporarily, on several different occasions, when I ran the recalibration procedure.

W/ the heater core removed and a good view of the blend door, I turned the key on and played w/ the temp setting. When I called for full heat, the blend door would move slightly and then return to the no-heat position. Then I tried the recal procedure, and the blend door moved to the full-heat position -- UNTIL I either moved the temp setting or turned the key off. Then it resumed its previous behavior. So I think the reason why the recal procedure stopped giving me temporary heat was becuz that's when the heater core got plugged.

Finally, I hooked up my DPDT switch to the actuator, and then I could put the blend door where ever I wanted and it stayed there. I installed the new heater core, and now I have heat! Good, hot, reliable heat! And I can make it cold if I want too.

 

[mrrsm]

Congratulations for taking @Mooseman 's suggestion in Post #6 and coming up with a "Novel Solution". It proves that no matter how may layers of confounding "Modern Engineering" are put in between a Problem and a Solution... if the parts involved use Electricity and involve DC Motors... With enough "Work" thrown at them... a reasonable, physical "Workaround" becomes possible. :>)