Yes, it's an A/C post

[kly5953]

Ok, had the vehicle 2 weeks or so. Love it, BUT....big but....the A/c has a mind of it's own. I asked it to blow hot, and it blows cold, turned it off and on again, tried hitting the A/C button, didnt work. Then the next day it works. Now, I live in GA and this might be a foreign idea to some people but, within 1 day I had to have the heater on full blast, and the A/C on full blast, and neither time did it do what I wanted. At some point it was blowing hot air on the passenger when I wanted 78° and good 78° air on me, then another time it was blowing cold on me when I wanted hot and hot on the passenger. This guy is all over the place, and I'm wondering if this sounds like a control module issue.
Please someone run me through some quick trouble shooting as I don't know where to start on this one. I'm wondering if maybe I should try pulling it out and plugging it back in to see if it starts working then.

No work has been completed other than swapping out the glove box, and the issue has been around since I got it. Up till now I just kept the air off and used the windows or the seat heaters to help out.

 

[exp500]

Do you have access to a 2way scanner like a Tech2?

 

[kly5953]

Do you have access to a 2way scanner like a Tech2?

I do not. I can maybe ask around if someone in the local atlanta area does

EDIT:

I just found a post on the chevy forum talking about this, and it looks like there might be a fix. If the unit had been replaced before, and the codes weren't reset, there could be an issue with calibration. Obviously at 175k it's possible this has happened. I am going to try removing the power cables, letting the vehicle sit for a while and then plug it back up. Then, turn the vehicle on and shut off the unit, let the hoe warm up, and turn the climate control unit back on. I'll get back to see if this works tonight.

 

[S33k3r]

Most likely the blend door actuator needs to be replaced. You are on the right track -- trying to recalibrate first. But if the actuator needs to be replaced, this is likely why the previous owner sold it.

 

[kly5953]

Do you have access to a 2way scanner like a Tech2?

Does it have to be the Tech2? a buddy of mine says he has a scanner at the shop that scans anything...I'm more old fashioned of trying to fix mechanical crap mostly so idk what i'm talking about with the scanners lol

Most likely the blend door actuator needs to be replaced. You are on the right track -- trying to recalibrate first. But if the actuator needs to be replaced, this is likely why the previous owner sold it.

From what I read, the blend door actuator only affects one side at a time, is it possible all of the actuators are bad at the same time?

 

[S33k3r]

Does it have to be the Tech2? a buddy of mine says he has a scanner at the shop that scans anything...I'm more old fashioned of trying to fix mechanical crap mostly so idk what i'm talking about with the scanners lol



From what I read, the blend door actuator only affects one side at a time, is it possible all of the actuators are bad at the same time?

I have a 2005 Suburban 2500, and it has three blend doors. One that is accessible from the driver's side, one that is accessible from the passenger side, and one that requires removal of the dash. Guess which one died on mine?

 

[kly5953]

I have a 2005 Suburban 2500, and it has three blend doors. One that is accessible from the driver's side, one that is accessible from the passenger side, and one that requires removal of the dash. Guess which one died on mine?

So after pulling the battery for about 2 hours and trying to reset it, the air is only blowing hot all the time. I havent been able to really do much else, but I can state that it's blowing hot air on both sides constantly. Would this help me to realize which blend door is bad? Cause I'm guessing it sounds like the one in the dash.

 

[S33k3r]

Have you replaced the dial,yet? If not, do you have a buddy who would let you borrow his?

 

[kly5953]

Have you replaced the dial,yet? If not, do you have a buddy who would let you borrow his?

No and No
I might have to go to the junkyard and take a look for some

I'm guessing that's the next step to see if the control unit works properly.
Is there a way to test this without replacing it with a different unit?
I can pull it from the dash and try to leave it plugged up if I can test all the wires for proper signals.

 

[S33k3r]

No and No
I might have to go to the junkyard and take a look for some

I'm guessing that's the next step to see if the control unit works properly.
Is there a way to test this without replacing it with a different unit?
I can pull it from the dash and try to leave it plugged up if I can test all the wires for proper signals.

I am sorry, but you just exceeded the limits of my knowledge. I'd search Youtube, or wait for someone with more experience on here to answer you. That said, it really sounds like the controller. If it were a blend door, it seems to me that it would blow cold in some places and hot in others. But don't take that to the bank either.

In terms of a "junkyard unit", watch FB Marketplace, Craigslist, OfferUp, etc. for part outs. Any of the GMT800 play form can have what you need, depending on the trim level. Just watch the interior pictures. I've seen those pieces go for $30-$60. At that price, it doesn't hurt to have one as a spare, even if that doesn't turn out to be the problem. And, you never know, you might find one where the button pictures aren't worn completely off...

Good luck.