Weird AC issue.
 

I have an 04 Silverado 2500 HD 4x4 with the 6.0, and the 4 speed auto. The air conditioner works fine most of the time, but sometimes the drivers side vents stop blowing cold air (the passenger side still does though). When I turn the truck off a few minutes, and turn back on, everything works again. Does anyone know why this happens? Is there anything I can do about it? Thanks.

Re: Weird AC issue.
 

Blend door actuator. It's been discussed here a few times, sometimes you can get lucky and reset them. There is a specific procedure for this if you don't have a Tech2. Others have been able to disassemble, clean, and grease them. Some people opt to just change them since they will probably do it again. The driver side blend door actuator is located under the hush panel (if equipped) towards the passenger side over the trans tunnel. It's 3 screws and a wiring harness to pull the old one out.

Re: Weird AC issue.
 

Here's a pic with the hush panel removed. You can see one of the mounting screws and the wiring harness plugged in.

Re: Weird AC issue.
 

Here's the actuators, case removed, and finally a pic of the area that needs to be cleaned. Those 2 tabs under the black gear ride on a strip that gets corroded or dirty. It's been reported that it can be cleaned well with alcohol, greased, and reassembled to work properly.

Re: Weird AC issue.
 

Thanks for the info, and awesome pictures. I will try this.

Re: Weird AC issue.
 

My actuator makes a clicking sound sometimes..... (gears slipping)....

Driver's side was not getting A/C a few times, but so far it hasen't done it for a long while.

I bought a replacement. It's in my garage when it finally fails.

Re: Weird AC issue.
 

I cleaned mine yesterday. So far, so good. We'll see how long it lasts. I cant help but to be a little frustrated with AC system and all of its electronics on these newer trucks, especially when I drive my '85 C10 around and feel the cold air hit me. The cable actuated system has yet to fail, even after 30+ years. The electric motor actuated system on the other hand has plagued the gmt800s since they were new.

Re: Weird AC issue.
 

Yea, I've seen gears like that before. In toys.

The slipping gear noise is just like when my CD tray at home won't close!!

Re: Weird AC issue.
 

How did the cleaning fix work out so far? I'm working on my sister's Tahoe now that apparently has 4 bad actuators on front and rear AC and would like to try cleaning instead of her spending a few hundred on new ones.

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I bought 1 actuator... About $45.00. More reliable than just fixing.

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I'm hoping Wyatt has had some success with it so far. I only have the truck to work on for a few days so I don't have time to order from a cheaper source, and 2 of the actuators are the pricey ones which are $141 each locally. I'm going to try pulling the 2 rears and the driver side blend door actuator and cleaning them first. She hasn't been worried about it since she lives in WV, but now that she's down here visiting it would be nice to have working AC.

Re: Weird AC issue.
 

So far mine still works, after cleaning. I've honestly thought about fabricating a lever that sticks out to attach to the nub that the actuator moves. it would look stupid, but at least I wouldn't have to deal with actuator failure anymore.

Re: Weird AC issue.
 

Thanks for the reply. I gave it a shot today and cleaned one of the buggy ones and so far, so good. We'll see how long it holds.

Re: Weird AC issue.
 

Is the strip copper or some other material?

You can clean copper up with alcohol then brass polish and then more alcohol using a cotton washcloth as an applicator. Make sure to get every drop of the brass polish off and make sure the copper is completely clean. You may have to re-apply the brass polish once or twice depending on how badly the connector is tarnished. I've done this with card edge connectors in antique test gear, antique computers, and antique game cartridges.
The last step is to lube it with dielectric grease or, on PC board card edge connections like the VSS and Cruise III modules, Deoxit S5 Shield.

Re: Weird AC issue.
 

I'm not sure what the strips are made of. Here are a few more pics if it clears anything up. There's not much to these things and from the caked up grease, I wonder if they just get sticky over time.

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Few more

Re: Weird AC issue.
 

That looks like conductive carbon similar to remote control boards and buttons.
The dried up dielectric grease they used can be cleaned off and replaced.
If it works after cleaning and re-greasing let it ride.

Re: Weird AC issue.
 

Sounds like fixing the lower actuator worked for you.

Here's a link for changing the upper acuator: https://www.instructables.com/id/How...de-temp-contr/

The upper looks like a major pain!

Does anyone have a flow diagram of the A/C system to get a better idea of what actuator location controls what function? I think there's 3 or 4 different actuators and they differ on what style A/C dash controller you have.

This looks like it could be such a major hassle!!!!

Re: Weird AC issue.
 

Well I took off my lower actuator and fixed the same problem as the OP.

Once you pull off the actuator you can turn the blend door open/closed by hand to confirm the air flow changes. Once I turned it by hand I was able to get cold air to the driver side.

My actuator was stuck...water got into the case and rusted the motor.

Now I have to find out where the water came from..... outside leak or condensation from the a/c system. It wasn't antifreeze from the heater core.

Thanks for posting your answers/experience!

Re: Weird AC issue.
 

I'll be changing my lower actuator sometime....... even though it does the 'clicking', it is still is working

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It could be a leaking evaporator core. I will warn you now, these are not fun at all to change out.

Re: Weird AC issue.
 

Full agreement.....

Anything to fix under a dash is never fun..... Unless the front seats remove easily. Which they don't.

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Thanks for the tip.

I looked up leaking evap core and it sounds like it should be gas vapor only. But, a clogged drain channel will lead to water in the footwell.

Anyone know if/where a drain tube would be?

Re: Weird AC issue.
 

Found a video on youtube.

It's on the firewall under the A/c Condenser in the engine bay.

Re: Weird AC issue.
 

Just to wrap up my end of the story, I pulled the Evap drain (mine was a rubber plug that I ended up replacing with a rubber tube) and a pint of water came out. Then, I did the cabin air filter retrofit. A 1/4” of mud and leaves was stuck to the piece I cut out and there was more on the evap. I brushed and wiped what I could before I put in the filters and sealed it up.

So, the mud and debris clogged up the drain which led to the actuator failure and water on the floor boards.

I’m pretty sure the a/c blows colder now.

Wil

Please forgive the slight hijack.