Blower motor resistor?

[tsmith1156]

Alright so since I first bought my tb about 4 years ago the 4 selection for the blower for a/c and heat didn't work, I got in this morning and started it and now 5 isn't working either. Do you think this is the blower motor resistor or a fuse or something else?

 

[christo829]

It's most likely the resistor pack. A fuse would kill all the power, not selected speeds. Do you have the manual controls or digital?

Replace the plug as well. Often the heat from the failing resistor pack damages the connection in the plug.

Good Luck!

Chris

 

[HARDTRAILZ]

Mine was no 5 for years then no 4 and the resistor fixed it right up

 

[DocBrown]

Cheap and easy fix!

 

[tsmith1156]

It's most likely the resistor pack. A fuse would kill all the power, not selected speeds. Do you have the manual controls or digital?

Replace the plug as well. Often the heat from the failing resistor pack damages the connection in the plug.

Good Luck!

Mine are the manual ones, are there any certain ones that will last longer than others or ones that are better?

Chris

Mine was no 5 for years then no 4 and the resistor fixed it right up

Ya mine has been no 4 for years and the 5 just went out but it actually came back on last night so idk what is going on

 

[christo829]

Hadn't really noticed a trend in one lasting longer than another. I just got mine from Rockauto. Have to go back and look up my order, but I *think* it was a Dorman. You might want to glance back through some of the other blower motor resistor related threads and see if one gets recommended more than another.

@tsmith1156: That intermittent behavior is most likely damage to the connector plug. When the resistor pack gets hot, some of that heat conducts along the metal contacts inside the plug. The plastic melts and allows the contact to shift.

Cheers-

Chris

 

[tsmith1156]

Hadn't really noticed a trend in one lasting longer than another. I just got mine from Rockauto. Have to go back and look up my order, but I *think* it was a Dorman. You might want to glance back through some of the other blower motor resistor related threads and see if one gets recommended more than another.

@tsmith1156: That intermittent behavior is most likely damage to the connector plug. When the resistor pack gets hot, some of that heat conducts along the metal contacts inside the plug. The plastic melts and allows the contact to shift.

Cheers-

Chris

Gotcha, I will look around, thanks

 

[webdawg]

I got the Dorman and it has worked good for a year so far and it is STILL working.. It is such an easy fixe I would not be worried, you can always replace on warranty.

 

[tsmith1156]

I got the Dorman and it has worked good for a year so far and it is STILL working.. It is such an easy fixe I would not be worried, you can always replace on warranty.

I got one from advance auto for under $40 and got it put in this afternoon so we will see how it goes!

 

[Team Dougherty]

Once you get speed 5 working. Check the current draw on the motor. on speed 5. It may have bad bearing and drawing more current than the system is rated for. Speed 5 does have its own fuse. #35

 

[AtlWrk]

IIRC new motors will draw somewhere around 21A on speed 5, give or take. I meant to measure mine when I put it in last year but there's a youtube video about testing the motor. I only mention this because most DMMs are only good to 10A DC and many are not protected by a fuse on that setting.

 

[C-ya]

I know these have a known resistor pack/plug issues, but it could be the switch on a manual set up. My GMC C1500 lost the top two speeds of 5 as I ran it in 3 (90% of the time) or 2. When I lost 1 as well, I decided to replace the switch and got all 5 speeds back. Could have been corrosion on the switch contacts kind of like the 4WD switch.

 

[tsmith1156]

Once you get speed 5 working. Check the current draw on the motor. on speed 5. It may have bad bearing and drawing more current than the system is rated for. Speed 5 does have its own fuse. #35

IIRC new motors will draw somewhere around 21A on speed 5, give or take. I meant to measure mine when I put it in last year but there's a youtube video about testing the motor. I only mention this because most DMMs are only good to 10A DC and many are not protected by a fuse on that setting.

I know these have a known resistor pack/plug issues, but it could be the switch on a manual set up. My GMC C1500 lost the top two speeds of 5 as I ran it in 3 (90% of the time) or 2. When I lost 1 as well, I decided to replace the switch and got all 5 speeds back. Could have been corrosion on the switch contacts kind of like the 4WD switch.

It works great after replacing it on Saturday, all 5 speeds run fine. It was definitely old when I took it out. Next step is new tires and headlights

 

[C-ya]

@tsmith1156 , I really did read that you changed out the resistor. Just slipped my mind by the time I was ready to reply. Glad it is working for you!

 

[tsmith1156]

@tsmith1156 , I really did read that you changed out the resistor. Just slipped my mind by the time I was ready to reply. Glad it is working for you!

Well until today, we're moving so I've been driving a lot today and it just quit working, guess I'll check the connection when I get home

 

[tsmith1156]

Does anyone know where the fuse is located?

 

[tsmith1156]

Alright so I checked the fuse and it's not the fuse... what's next?

 

[Mooseman]

Check the connectors at the resistor and the blower motor. Mine were melted.

 

[tsmith1156]

Check the connectors at the resistor and the blower motor. Mine were melted.

On the one that you put in new? I'm gonna buy a new one tomorrow and try and install it tomorrow night to see if it works and hope it's not the actual blower itself

 

[AtlWrk]

There are two fuses:
#35 is a 40A big square J-case fuse in the front fuse block
#44 in the rear fuse block

If you blew a fuse then I'd take a serious look at your motor. These fuses are oversized for this system which is partially why we melt connectors and resistor packs before blowing a fuse when the motor starts to age.

Even if you didn't, take a close look at the connector that goes into the resistor pack for signs of overheating: discoloration, melted plastic, etc. If any is present then you'll need to replace the connector too (they sell replacement pigtails you splice in). Mine had melted both there and at the connector on the motor itself--unfortunately I had to replace the motor too. But I would have done this anyway--the motor spun fine but the brushes/commutator were very worn.

That said, there have been instances of junk replacement modules, too.

 

[tsmith1156]

There are two fuses:
#35 is a 40A big square J-case fuse in the front fuse block
#44 in the rear fuse block

If you blew a fuse then I'd take a serious look at your motor. These fuses are oversized for this system which is partially why we melt connectors and resistor packs before blowing a fuse when the motor starts to age.

Even if you didn't, take a close look at the connector that goes into the resistor pack for signs of overheating: discoloration, melted plastic, etc. If any is present then you'll need to replace the connector too (they sell replacement pigtails you splice in). Mine had melted both there and at the connector on the motor itself--unfortunately I had to replace the motor too. But I would have done this anyway--the motor spun fine but the brushes/commutator were very worn.

That said, there have been instances of junk replacement modules, too.

I hope it's just a bad replacement, I don't know how to do the wiring and all that and I really don't want to try to replace the motor. There is some air that comes through the vents but it's just like outside air, the heat and A/C still work if that means anything

 

[Realism]

I went through replacing mine earlier this year and had to do some troubleshooting with excellent help from my fellow posters.
When you have it installed and on high check the voltage going to your blower motor to see if you are getting full voltage. If so then could be your blower motor went out, or it is worn to the point that it is creating excess draw iirc which would cause the FET in your module to fry.
In either case, pulling your motor out and checking its level of clean would be helpful. Debris and leaves trapped up in there and in the interior of the motor can cause some issues. I'm glad I pulled mine out and cleaned it out, it looked like there was a heat build up and I ended up with some crispy debris, glad there wasnt a fire from it. But it spun smoother after cleaning it.

One thing I found out later on another site was about the FET in the module, which is nearly always the culprit when you lose your blower speeds. One guy just went to radio shack and got another FET and soldered the new one in after removing the burnt one, Solved his problem and only cost him some change instead of buying a new module.

Hope your replacement holds out for you.

 

[tsmith1156]

I went through replacing mine earlier this year and had to do some troubleshooting with excellent help from my fellow posters.
When you have it installed and on high check the voltage going to your blower motor to see if you are getting full voltage. If so then could be your blower motor went out, or it is worn to the point that it is creating excess draw iirc which would cause the FET in your module to fry.
In either case, pulling your motor out and checking its level of clean would be helpful. Debris and leaves trapped up in there and in the interior of the motor can cause some issues. I'm glad I pulled mine out and cleaned it out, it looked like there was a heat build up and I ended up with some crispy debris, glad there wasnt a fire from it. But it spun smoother after cleaning it.

One thing I found out later on another site was about the FET in the module, which is nearly always the culprit when you lose your blower speeds. One guy just went to radio shack and got another FET and soldered the new one in after removing the burnt one, Solved his problem and only cost him some change instead of buying a new module.

Hope your replacement holds out for you.

The replacement didn't do anything, I'm gonna check the blower motor this weekend and see

 

[AtlWrk]

I went through replacing mine earlier this year and had to do some troubleshooting with excellent help from my fellow posters.
When you have it installed and on high check the voltage going to your blower motor to see if you are getting full voltage. If so then could be your blower motor went out, or it is worn to the point that it is creating excess draw iirc which would cause the FET in your module to fry.
In either case, pulling your motor out and checking its level of clean would be helpful. Debris and leaves trapped up in there and in the interior of the motor can cause some issues. I'm glad I pulled mine out and cleaned it out, it looked like there was a heat build up and I ended up with some crispy debris, glad there wasnt a fire from it. But it spun smoother after cleaning it.

One thing I found out later on another site was about the FET in the module, which is nearly always the culprit when you lose your blower speeds. One guy just went to radio shack and got another FET and soldered the new one in after removing the burnt one, Solved his problem and only cost him some change instead of buying a new module.

Hope your replacement holds out for you.

The FET replacement only applies to blower modules for the auto HVAC controls. They use a different type of control module. I assume, since the OP is referring to selectable 1-5 speeds, that he has the manual controls which uses a different "resistor" pack which is not fixable.

If fuse 44 in the rear fuse block is not blown (you did check this right? it will take out all speeds) then you are looking at either the blower motor, wiring or, worst case, the HVAC head unit itself. Double check the connections into the resistor pack and the motor. Physically look at the motor where the connector plugs in--this is where mine melted bad enough to completely lose the connection making me lose all speeds.

 

[tsmith1156]

The FET replacement only applies to blower modules for the auto HVAC controls. They use a different type of control module. I assume, since the OP is referring to selectable 1-5 speeds, that he has the manual controls which uses a different "resistor" pack which is not fixable.

If fuse 44 in the rear fuse block is not blown (you did check this right? it will take out all speeds) then you are looking at either the blower motor, wiring or, worst case, the HVAC head unit itself. Double check the connections into the resistor pack and the motor. Physically look at the motor where the connector plugs in--this is where mine melted bad enough to completely lose the connection making me lose all speeds.

I do not have a diagram for the rear fuse block so I was unsure which fuse #44 was.

 

[AtlWrk]

There's a diagram in the owners manual (which can be downloaded from here, somewhere, if you don't have one) and I thought there was one on the underside of the fuseblock lid? Or google?

It's #44 "HVAC" or "Heating Ventilation and Air", but be warned there are others labeled things like "HVAC I" and "HVAC B" too. It's a 30Amp (green) fuse and there are probably only a few back there so it wouldn't be hard to check em all.

 

[tsmith1156]

I just saw this thank you, there is a diagram under the lid of the one under the hood but not under the rear seat

 

[tsmith1156]

I looked on google and couldn't find a diagram for the rear one for the trailblazer (I found a bunch of other ones) do you happen to know off the top of your head where the fuse is located in there?

There's a diagram in the owners manual (which can be downloaded from here, somewhere, if you don't have one) and I thought there was one on the underside of the fuseblock lid? Or google?

It's #44 "HVAC" or "Heating Ventilation and Air", but be warned there are others labeled things like "HVAC I" and "HVAC B" too. It's a 30Amp (green) fuse and there are probably only a few back there so it wouldn't be hard to check em all.

 

[tsmith1156]

Alright so I recently have been having problems with my fan speeds, no speed is working, blower motor resistor has been replaced. I have been told since no speeds at all are working it is most likely the blower motor, before I dig into it does anyone have any opinion? I don't have anywhere that I can test the wiring or anything, plus idk how to do that.

 

[Sparky]

Invest $10 in a cheap meter to test to see if you're getting power at the harness before you go spending tons more on a motor you may not need.

But as always check your fuses first.

 

[tsmith1156]

I'm very new at all this work, when I get the meter do I need to just touch it to the wire or do I have to actually like cut the wire to touch it to the inside? I need to be able to find the fuse in the rear fuse block first

Invest $10 in a cheap meter to test to see if you're getting power at the harness before you go spending tons more on a motor you may not need.

But as always check your fuses first.

 

[budwich]

look at this way... learning how to use a meter won't "save your life"... but it will make your future much better ...

the internet / youtube has lots of good stuff on the basics of using a meter. Do a little reading / watching and you will quickly become a "pro" like the rest of us...

PS. You aren't going to be cutting wires, the first test is a resistance measurement (ohms) of the two wires going to the motor (basically power and ground for the motor).

 

[tsmith1156]

look at this way... learning how to use a meter won't "save your life"... but it will make your future much better ...

the internet / youtube has lots of good stuff on the basics of using a meter. Do a little reading / watching and you will quickly become a "pro" like the rest of us...

PS. You aren't going to be cutting wires, the first test is a resistance measurement (ohms) of the two wires going to the motor (basically power and ground for the motor).

Idk about me becoming a pro but I can try haha, I just wish I could find a diagram for the rear fuse block so I can check the fuse!

 

[budwich]

you got to start somewhere...
anyways, you can also readly check the motor operation by running battery and ground directly to the motor leads at the connector (carefully) and see what happens.

 

[Sparky]

Put the meter in DC volts (20V range, usually), then stick hte probes on the two contacts that go to the motor to see if you are getting voltage. If you're getting your voltage at the plug, then your supply is likely fine. If you have nothing, then the supply is bad for whatever reason.

 

[tsmith1156]

you got to start somewhere...
anyways, you can also readly check the motor operation by running battery and ground directly to the motor leads at the connector (carefully) and see what happens.

I don't have a battery or anything to test like that

Put the meter in DC volts (20V range, usually), then stick hte probes on the two contacts that go to the motor to see if you are getting voltage. If you're getting your voltage at the plug, then your supply is likely fine. If you have nothing, then the supply is bad for whatever reason.

Do I buy a meter or probe or does it come as a kit or something? I'm not sure what I'm doing haha sorry

 

[Mooseman]

They usually come with the probes. Something at $20 would suffice, like these:

https://www.amazon.com/dp/B000X5TSUA/?tag=gmtnation-20

https://www.amazon.com/dp/B00KXX2OYY/?tag=gmtnation-20

You can get them anywhere. Walmart, parts stores, Harbor Freight, Home Depot.

And as mentioned, lots of videos on YT on how to use them.

 

[tsmith1156]

Man I'm gonna get confused...

They usually come with the probes. Something at $20 would suffice, like these:

https://www.amazon.com/dp/B000X5TSUA/?tag=gmtnation-20

https://www.amazon.com/dp/B00KXX2OYY/?tag=gmtnation-20

You can get them anywhere. Walmart, parts stores, Harbor Freight, Home Depot.

And as mentioned, lots of videos on YT on how to use them.

 

[Sparky]

You're over thinking it, it isn't hard. Just watch a couple youtube videos and it'll all make sense.

 

[budwich]

I don't have a battery or anything to test like that

SURE you do... its in your truck... just get some wire and connect it up carefully.

Do I buy a meter or probe or does it come as a kit or something? I'm not sure what I'm doing haha sorry

I think the alternative is buy a new truck... or maybe cheaper, head to the "stealership"... :-(

I think you might be ready for "life lesson"...

PS. here is an example of using a meter to measure resistance.
http://www.wikihow.com/Measure-Resistance