HVAC Controls

[INW-Iron-Steel]

Module Master shows they rebuild your style of AC module for $45.

Looking at the Module Master website it looks like the only repair they offer is for the back-lighting, not for any of the "functional" parts. I wouldn't mind sending my current one out to be rebuilt after I get this OEM one installed.

Any other possible rebuilders I could look into?

 

[ORVietVet]

Automotive Electronics Repair | Auto Tech Rescue

We specialize in the repair of automotive electronics including instrument cluster repair, speedometer repair, climate control repair, modules, ecm, & more!

autotechrescue.com

 

[INW-Iron-Steel]

Automotive Electronics Repair | Auto Tech Rescue

We specialize in the repair of automotive electronics including instrument cluster repair, speedometer repair, climate control repair, modules, ecm, & more!

autotechrescue.com

Digging through the Auto Tech Rescue site, it looks like they only offer repair for the automatic ones. Darn. I'll keep looking, no rush, I just won't toss the old one when I replace it. Thanks for all the help guys!

 

[ORVietVet]

Did you contact them to be sure? Maybe they can recommend a place.

 

[Pauly1119]

I’d do a OEM one on eBay and then do the re-sync procedure for your actuators.


Silverado, remove the HVAC/ECAS-10A fuse for a minute, replace it, then cycle the ignition (on for 10 seconds, off, repeat three times), start the truck, and set the HVAC controls to a neutral position (72°F or auto mode) and let it idle for 1-2 minutes without adjusting anything.

 

[INW-Iron-Steel]

I’d do a OEM one on eBay and then do the re-sync procedure for your actuators.


Silverado, remove the HVAC/ECAS-10A fuse for a minute, replace it, then cycle the ignition (on for 10 seconds, off, repeat three times), start the truck, and set the HVAC controls to a neutral position (72°F or auto mode) and let it idle for 1-2 minutes without adjusting anything.

Thanks for the info on this and the re-sync procedure! Do you happen to know of a source to GM service manual type literature on re-syncing the actuators? Not that I don't trust a fellow member, I just like to read up on a repair I've never done and try to get everything right the first time.

 

[INW-Iron-Steel]

I forgot to update this post. I've been buried in repairs/mods to other vehicles and it's not quite "hot" yet, so the AC on the Sierra has been on the back burner. Just finished up swapping the 93' to roller cam. Now I'm getting the 82' ready for a couple state road trip back home, which involves tidying up some small stuff I've been putting off for years and swapping the double pumper for a more cruise friendly AVS style carb I took off years ago.

Anyway, the HVAC control came from the ebay seller and was totally worth the money. Definitely a NOS piece with Delphi stickers! The same seller could not find a clutch for my rig. I ended up getting a Factory Air branded clutch. It was cheap, and if it burns up I'll just get a whole new compressor. The Sierra AC will be the next thing I tackle after the 82' road trip. My work schedule lately has really been eating into my car time... Damn career.

 

[Pauly1119]

Thanks for the info on this and the re-sync procedure! Do you happen to know of a source to GM service manual type literature on re-syncing the actuators? Not that I don't trust a fellow member, I just like to read up on a repair I've never done and try to get everything right the first time.

Thanks for the info on this and the re-sync procedure! Do you happen to know of a source to GM service manual type literature on re-syncing the actuators? Not that I don't trust a fellow member, I just like to read up on a repair I've never done and try to get everything right the first time.

I know there was a factory memo but I’m not sure where it is. I have done it a few times myself.

 

[INW-Iron-Steel]

Getting after the AC on the Sierra and coming back to this thread for the re-sync procedure (thanks @Pauly1119). Here's some pictures of the progress so far. New clutch is on, which should be the most involved task. I found a really good video for the process on Youtube. I'll find the video and link it below later. The two snap-rings on this really test your patience, especially the larger inner one. I also swapped out the relay my buddy and I modified like 10 years ago. The original relay had been superseded to a new part number, but still a GM genuine used here. Now to swap the HVAC control and test!

Also, don't worry, I'm not leaving that cracked/worn out AC belt. I have no doubt that belt is original with 260K on it. I'm going to eliminate the tensioner and go to a stretch belt, but Amazon has let me down. I have the local Irish guys ordering one in too, and that should be here tonight. Whatever one gets to me first will go on.

 

[INW-Iron-Steel]

Okay, unfortunate news. The new HVAC control made no difference. I pulled the HVAC fuse, re-installed, and then cycled the key 3 times. AC button does not engage the compressor. My fan shuts off when the knob is turned to "4" but operates on 3 and 5. I am also only getting hot air out of the driver side vents. It seems that the slider is doing nothing. When I move the passenger temperature slider the temperature changes and I can hear the actuators moving. When I move the driver slider, nothing. Just heat. Going to check fuses and do more research on this.

 

[ORVietVet]

Okay, unfortunate news. The new HVAC control made no difference. I pulled the HVAC fuse, re-installed, and then cycled the key 3 times. AC button does not engage the compressor. My fan shuts off when the knob is turned to "4" but operates on 3 and 5. I am also only getting hot air out of the driver side vents. It seems that the slider is doing nothing. When I move the passenger temperature slider the temperature changes and I can hear the actuators moving. When I move the driver slider, nothing. Just heat. Going to check fuses and do more research on this.

Or blend door problems. Notorious problems.

 

[INW-Iron-Steel]

Or blend door problems. Notorious problems.

You're right, the "made no difference" part I was talking about was mainly in reference to the ac button not cycling the clutch. But, the parts I replaced are functioning as they should. I am just dealing with a multitude of problems that are just now rearing their heads. I jumped the low pressure sensor and cycled the clutch and it worked. Then, I put my gauges on it and saw zero pressure on the low side, and greater than 100psi on the hot side with the clutch disengaged. So, problem #1- clogged orifice tube. Problem #2 is likely the driver side blend door actuator, and problem #3 is likely the fan resistor. This simple AC repair just got a little bit more complicated...

 

[AuroraGirl]

Okay, unfortunate news. The new HVAC control made no difference. I pulled the HVAC fuse, re-installed, and then cycled the key 3 times. AC button does not engage the compressor. My fan shuts off when the knob is turned to "4" but operates on 3 and 5. I am also only getting hot air out of the driver side vents. It seems that the slider is doing nothing. When I move the passenger temperature slider the temperature changes and I can hear the actuators moving. When I move the driver slider, nothing. Just heat. Going to check fuses and do more research on this.

My 4 also doesnt work, your truck is likely part of the many who had a issue with the blower fan and the resistor/control assembly in the 2000s

Also, the HVAC controller has TWO possible operations on the AC button. 2003 or 2004 they CHANGED the behavior of the button to be (forgive me if im backward) light-on-means-ac-is-on
From the previous "light on means AC off"
The buttons had a difference in graphic on the top, the old ones which cancel the AC had SLASHES through teh snowflake
But the one that tells you it is on doesnt have slashes


here is the 2003/4 changeover descriptions.

Heres something that may be relevant?:

 

[INW-Iron-Steel]

I pulled the driver blend door (temperature) actuator. The luck was good on this one, as that actuator is by far the easiest one to get at. I was going to slap an old actuator I had pulled out of the 93 burb in if it was the same. One of the levers for the mode had popped out of place on that rig. I figured it was the actuator acting up so I had one on hand, and since it was out, I just installed the new one. Anyway, upon removing the one from the Sierra, I compared them and they are almost exactly the same EXCEPT for one pin on the wiring plug. I attached a picture of the two for comparison (Blue label one is from the 93).

Just a reminder to double check the pin-out on these when buying, or if you have a few laying around. Since I had it out I punched the OEM part number into rock auto and purchased a couple different brands of actuators, along with an AC kit (accumulator/orifice tube(s)/gaskets), and a blower motor resistor to hopefully get all fan speeds back. Now for the weird part. I put the old actuator pictured above back in the truck for the time being until new parts get here. Out of curiosity, I started it up and moved the temperature sliders, and wouldn't you know it, that driver temperature blend motor came back to life. I punched the AC button and out of amazement the clutch kicked on and all my vents got icy cold. It didn't build pressure on the high side only, it kept functioning as normal for more than 5 minutes. I guess all I needed to do was purchase the parts to fix my problem, but not actually install them... Huh, who knew it was that easy.

On a serious note, I'll replace that actuator since it's on the fritz, and hopefully the resistor restores all fan speeds. As far as the AC, if I don't need to evacuate the system, repair, and re-charge, that would be a massive win. I guess only time will tell on that one. Gotta love old trucks and their quirks.

 

[INW-Iron-Steel]

So, I ordered two mode actuators for comparison. With the one needing replacement being extremely easy to remove, I figured I would give the $15 SKP a shot. The two parts showed up in the exact same box and looked exactly the same physically, except for the printed on part number. The FourSeasons part was actually worse, as the two sides of the case didn't fully fit together properly allowing the internals to shake around. I installed the the SKP and sent the FourSeasons back. SKP is working fine for now.

 

[INW-Iron-Steel]

Update on the revamp. My AC would work for a while, and then randomly it wouldn't. Watching my pressure climb until the high switch kicked the clutch off proved I had an obstruction. I ended up recovering the system, and flushing the condenser and evaporator. The condenser was clear, but I blew some nasty stuff out of the evaporator. Orifice tube was also fairly plugged up. Went to charge after getting everything back together and my compressor clutch wouldn't engage with the low pressure switch bypassed. After some troubleshooting, I found the ground side on the clutch pigtail was melted/not making contact. I wired in a new connector and added a ground directly to the chassis for the AC clutch. AC working great. Now I'm tempted to replace the fan clutch with a heavy duty unit to improve airflow over the condenser at idle. Moving, especially on the interstate, it is freezing me out.

My simple "I'm just gonna replace the HVAC controls" job snowballed into a rather involved project. But, we're functioning good now. All told, I am always reminded how much I like working on GMT800s. Only problem I have at this point is the better half keeps taking my rig to work...

Parts replaced:
-HVAC controller
-AC clutch
-AC relay
-Blend door actuator
-Blower motor resistor
-AC clutch connector
-Full AC recovery/clean/recharge (new accumulator of course)

 

[ORVietVet]

Update on the revamp. My AC would work for a while, and then randomly it wouldn't. Watching my pressure climb until the high switch kicked the clutch off proved I had an obstruction. I ended up recovering the system, and flushing the condenser and evaporator. The condenser was clear, but I blew some nasty stuff out of the evaporator. Orifice tube was also fairly plugged up. Went to charge after getting everything back together and my compressor clutch wouldn't engage with the low pressure switch bypassed. After some troubleshooting, I found the ground side on the clutch pigtail was melted/not making contact. I wired in a new connector and added a ground directly to the chassis for the AC clutch. AC working great. Now I'm tempted to replace the fan clutch with a heavy duty unit to improve airflow over the condenser at idle. Moving, especially on the interstate, it is freezing me out.

My simple "I'm just gonna replace the HVAC controls" job snowballed into a rather involved project. But, we're functioning good now. All told, I am always reminded how much I like working on GMT800s. Only problem I have at this point is the better half keeps taking my rig to work...

Parts replaced:
-HVAC controller
-AC clutch
-AC relay
-Blend door actuator
-Blower motor resistor
-AC clutch connector
-Full AC recovery/clean/recharge (new accumulator of course)

I did a lot of a/c work when I lived in KC, Mo. Hot and humid temps. Every single time I opened up a system, that could not document recent accumulator and orifice, I insisted on both new and a flush.

Did you use air pressure and get between the radiator and condenser and blow the condenser out from the inside to the front? You should. That heavy duty fan clutch will be noisy. If the one on there now keeps engine at temp and a/c cold, there is no need. the air blow out on the condenser will do the best for the system. I used to have a long wand hand trigger blower that could reach to the bottom of the condenser.

 

[AuroraGirl]

Update on the revamp. My AC would work for a while, and then randomly it wouldn't. Watching my pressure climb until the high switch kicked the clutch off proved I had an obstruction. I ended up recovering the system, and flushing the condenser and evaporator. The condenser was clear, but I blew some nasty stuff out of the evaporator. Orifice tube was also fairly plugged up. Went to charge after getting everything back together and my compressor clutch wouldn't engage with the low pressure switch bypassed. After some troubleshooting, I found the ground side on the clutch pigtail was melted/not making contact. I wired in a new connector and added a ground directly to the chassis for the AC clutch. AC working great. Now I'm tempted to replace the fan clutch with a heavy duty unit to improve airflow over the condenser at idle. Moving, especially on the interstate, it is freezing me out.

My simple "I'm just gonna replace the HVAC controls" job snowballed into a rather involved project. But, we're functioning good now. All told, I am always reminded how much I like working on GMT800s. Only problem I have at this point is the better half keeps taking my rig to work...

Parts replaced:
-HVAC controller
-AC clutch
-AC relay
-Blend door actuator
-Blower motor resistor
-AC clutch connector
-Full AC recovery/clean/recharge (new accumulator of course)

A pusher fan is better than a noisier fan (that can increase cfm)

A heavy Duty fan will be more noise but mostly when driving. So your gain at idle is going to be lesser.

A jeep auxillary fan might fit inside the shroud. (2006 Cherokee is what I seen one on)

Explain where and how you did the ac clutch ground to chassis. What did you tie into and where is the ground at.

 

[INW-Iron-Steel]

I did a lot of a/c work when I lived in KC, Mo. Hot and humid temps. Every single time I opened up a system, that could not document recent accumulator and orifice, I insisted on both new and a flush.

Did you use air pressure and get between the radiator and condenser and blow the condenser out from the inside to the front? You should. That heavy duty fan clutch will be noisy. If the one on there now keeps engine at temp and a/c cold, there is no need. the air blow out on the condenser will do the best for the system. I used to have a long wand hand trigger blower that could reach to the bottom of the condenser.

I am the same, any time I open a system it gets an orifice and an accumulator. I blew everything around the condenser and radiator clear with air also. I am leaning heavy duty clutch because my AC temps are warming up at idle. As soon as I start moving, even just barely moving, vent temp cools down. Also, the fan clutch might be the original. It has at least been on there for 10 years and 100,000 miles.

A pusher fan is better than a noisier fan (that can increase cfm)

A heavy Duty fan will be more noise but mostly when driving. So your gain at idle is going to be lesser.

A jeep auxillary fan might fit inside the shroud. (2006 Cherokee is what I seen one on)

Explain where and how you did the ac clutch ground to chassis. What did you tie into and where is the ground at.

The pusher fan is a good idea. I am not huge on electric fans of any kind, but that is mainly because of my past experience with electric fans. I might have to think about adding an auxillary fan.

I'll take a picture of the chassis ground and post a picture.

 

[INW-Iron-Steel]

Here's a photo of the ground on the frame just behind the sway bar


Not the same vehicle, but same ground mod on another GMT800 a few years back. Including my 04, this is now the 4th GMT800 I have done this on. The ground in the harness often loses continuity over the years. I did it to mine not because the ground was bad, but because I was splicing in a new connector and didn't want to have to go back later. On the left is the vehicle side of the harness with ground spliced in. Right side is factory wire running to the AC coil.