2003 GMC YUKON Automatic A/C
So I've been having a problem with my ac, not that it's not cold or anything, but the blower motor just doesn't work at all sometimes. I replaced the blower motor and the blower motor resistor with OEM parts and the plug that has a recall with a plug that has bigger wires so they don't melt. So sometimes when I go to start my day, hop in and start it up and turn the fan on, nothing happens, but the plug I can unplug and plug it back in and it'll work fine no problems until the next cycle off and on. Someday it will work just fine how it should. My solder joints and good and strong so I know it gets a good connection. Not sure about the voltage it should be getting maybe it gets too much? Red wire is at 12.xx volts. Purple or the middle one the small one gets 5 volts when the ac is off and full speed it goes down as you'd expect, even if it's not blowing, the voltage will still go down as if it was blowing but it's not. And black is ground ofc. I would love to have some Intel on this issue. I've replaced everything except the climate control module not sure if that can cause that issue bc it's getting proper voltage. Maybe just a faulty resistor out the box idk. Please help
Please post all the info in the instructions, every time.
Put a summary of the problem in the title, not the vehicle.
Thank you.
I already did in the first post but nobody responded to it so I'm posting again
"posting again" violates our forum rules (you can read them on the front page), so don't do it. You also need to post the info each time.
I'm sorry that your question slipped through without an answer. It doesn't normally happen. But Scotty is on vacation so we're a little short. If it ever happens, just post an addition to the topic and it will automatically get bumped up to the top of the list. I'm going to merge the topics now ...
I don't think you have a resistor. There is a blower motor controller that duty cycle pulses the motor.
The controller gets constant power on the red wire, and a speed signal on the purple+white striped wire. (0 to 12V depending on speed setting)
Here are the blower motor diagnostic procedures:
Definitely have a resistor
post a photo of it
It is automatic climate control module how would iadd a picture
It's in the FAQ but just go to https://postimages.org/
Select "Choose images"
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Choose the image saved to your device
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Then choose the second option down: "Direct Link"
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The button to the right of that link Copies the URL to your clipboard
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Paste that URL into your post
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@jack62 it's actually in the 'forum guide' : https://carkiller.com/scottykilmer/notice/read-this-first/
But postimages has been unreliable lately. imgur.com seems bulletproof
OK, sorry. But I always use https://postimages.org/ and have never had any issues with it
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My computer is a chromebook
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But if imgur.com is more reliable across different operating systems I'll defer to your expertise/experience on this
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Either way I screwed up. If the instructions are in the Forum Guide, not the FAQ. My bad. I should have checked before I posted that
I don't think it has to do with operating systems. It's something with image caching on the carkiller server. Sometimes it just acts up and breaks images.
stuff like "server imaging caching" is way above my pay grade
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I'm happy to take your word for it.
https://www.picdrop.com/dakotazellers/T3P78B76qQ
I don't know how to use imgur but added a photo of the resistor that I replaced
There's only 3 wires plugging into the back of the resistor
That's a control module for automatic AC
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The resistor assembly for manual AC looks like this
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https://imgur.com/a/gd49kUG
??? Both the resistor and control module are in there
The one you posted is for a manual control module not automatic the one with silver fins is the one all automatics use
Yes, the one you have is a control module. Not a resistor assembly. It works on PWM (Pulse Width Modulated) ((Ground)) voltage signals from the HVAC climate control head
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Blower Motor Control Processor System Description
The blower motor control processor controls the speed of the blower motor by increasing or decreasing the voltage drop on the ground side of the blower motor. The HVAC control module provides a low side pulse width modulated signal to the blower motor control processor over the blower motor speed control circuit. As the requested blower speed increases, the HVAC control module increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the HVAC control module decreases the amount of time that the signal is modulated to ground.
That makes no sense at all... only one can be called a control module and everywhere you look to buy one even the dealerships it's called a resistor. And my question to fix this issue is still in the open
Still confused on the whole situation on what I should do to fix the issue
I want to think I just got a faulty resistor bc I can take the 12v (red wire) away and back on and it'll work just fine. I have the connections as heavy duty butt connectors so I can just unplug them when I need to if I need to. Whenever it happen I unplug the red wire and plug it back in and it works. Wether I unplug the entire plug or just the red still works after either
Yeah, I know. They call these control modules "resistor assemblies" all the time in the parts descriptions. But they're wrong and usually in the description for automatic HVAC systems if you read through them you'll see "control module"
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But you're right. Now that we know what we're dealing with here, let's try to figure out why unplugging the blower control module (resetting it) is necessary to make it work consistently
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I'll do some research and see if I can find some reasons
there's no resistor. Follow the diagnostic steps I posted above (Blower Motor Inoperative, Blower Motor Malfunction). If the control module is faulty, then you need to replace it with the part in the photo I posted below.
Excuse me for jumping in on your conversation Joe
By all means, Jack.
I saw "automatic AC" in the title. But maybe he was referring to the transmission?
The manual system looks like this:
added a photo of the resistor
that's a blower motor control module. But don't buy this! (read below)
GM Part No.: 89018778 Module,Heater & Blower & A/C Control
https://www.gmpartsgiant.com/parts/gm-module-89018778.html
There's only 3 wires plugging into the back of the resistor
purple + black wires for motor
then there's a socket for your other three wires: power, ground, and speed signal.
Just like the electrical schematic shows.
even the dealerships it's called a resistor.
people are just clueless, or use the incorrect names . Happens all the time.
That looks pretty similar to the "resistor" in my car, which uses a power transistor to provide continuously-variable, electronically-controlled blower speed. The protruding heat sink sits in the air stream of the blower to keep the unit cool.
HOWEVER, this part is flawed and obsolete. GM discontinued it and released a different one. I'm trying to find a good image ....
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https://www.youtube.com/watch?v=2l_z44eQmt8
it's a pretty ubiquitous design, Chuck.
It's not stuck on a setting or fan speed
I posted the video as an installation reference
Oh I know how to install one I've already replaced it but think it's faulty or if the box
2003 GMC
So I've been having a problem with my ac, not that it's not cold or anything, but the blower motor just doesn't work at all sometimes. I replaced the blower motor and the blower motor resistor with OEM parts and the plug that has a recall with a plug that has bigger wires so they don't melt. So sometimes when I go to start my day, hop in and start it up and turn the fan on, nothing happens, but the plug I can unplug and plug it back in and it'll work fine no problems until the next cycle off and on. Someday it will work just fine how it should. My solder joints and good and strong so I know it gets a good connection. Not sure about the voltage it should be getting maybe it gets too much? Red wire is at 12.xx volts. Purple or the middle one the small one gets 5 volts when the ac is off and full speed it goes down as you'd expect, even if it's not blowing, the voltage will still go down as if it was blowing but it's not. And black is ground ofc. I would love to have some Intel on this issue. I've replaced everything except the climate control module not sure if that can cause that issue bc it's getting proper voltage. Maybe just a faulty resistor out the box idk. Please help
If you've gone through the troubleshooting in the service module, and you've determined the blower control module is faulty, then this is the replacement you need.
it costs around $100 from your GM dealership
https://www.buykippscottgmparts.ca/oem-parts/gm-hvac-blower-motor-control-module-19260762
Oh I see how it works. So the 3 that go into the module are the red orange and purple and the other outside wires purple and black go to the blower motor? Will this still make my automatic ac work properly? So I can just leave it on auto?
Yes, just like the schematic shows. And yes this is the correct part for automatic HVAC. I don't know if it will fix your problem. Like I said before, you need to verify if your control module failed by following the diagnostic steps I posted.
Does this also fix the recall on melting plugs?
It should