05 gmc sierra ac blows hot air

[jpratt]

I installed a CAI on my truck this afternoon and had the battery disconnected as per the instructions. Everything was fine till I rolled up the windows and turned on the AC, to my surprise it blows hot air instead of cold air. All settings have ho t air coming out. I worked fine before I disconnected the battery. I went back under hood to make sure the belt was not off the pulleys, everything looks correct. I disconnected the battery again but it still blows only hot air.

Any ideas.

 

[88ZNX]

I've heard of this twice, one had to replace the control unit, and the other started to work again after a few days.

 

[getchasum]

Our 04 Avalanche does this time to time? Last time it happened we were on a 5 hr trip to the beach. Talk about rasing cane, the family was near dead by time we got there. Started working fine again?

 

[jpratt]

Thanks for the replies. I guess I will take the wait and see attitude with this. Glad is the cool time of year.

 

[conn84gn]

Gm had a lot of problems with the fan resistor and plug on all the trucks
Most of the time you start losing fan setting 1-5 try wiggling the plug.
Could be the resistor
If you replace the resistor replace the plug too or it will take out the new resistor

Resistor $35.00 NAPA
Plug $12.00 off a diesel board called dieselplace.com

 

[SGRIM]

Wow, my 05 GMC 2500 wrecker has the same problem from time to time... Fan just stops and starts working at will. Just started recently...

 

[conn84gn]

In your case it is resistor
Not sure about the AC problem but it may have been talked about on the board
Dieselplace.com has a lot of good info on the GM trucks (Just GM trucks)
Sign on and do a search

 

[getchasum]

Found this on line last night......

Sequence to reset HAVA/ECAS accumulator door motor, sometimes need when battery has been disconnected causing accumulator door motor not to cycle properly.

Start the vehicle
Turn the A/C On
Pull the 10A HAVA/ECAS fuse - in under hood fuse box
Wait 30 seconds
Turn ignition off
Re-plug 10A HAVA/ECAS fuse

May have to be repeated, but test prior to repeating


Seems like this is a global problem with GM trucks and resetting seems to cure the problem.

 

[jpratt]

Found this on line last night......

Sequence to reset HAVA/ECAS accumulator door motor, sometimes need when battery has been disconnected causing accumulator door motor not to cycle properly.

Start the vehicle
Turn the A/C On
Pull the 10A HAVA/ECAS fuse - in under hood fuse box
Wait 30 seconds
Turn ignition off
Re-plug 10A HAVA/ECAS fuse

May have to be repeated, but test prior to repeating


Seems like this is a global problem with GM trucks and resetting seems to cure the problem.

I will try this as soon as the wife gets back. Sounds like best solution so far.

 

[conn84gn]

Good info to know
I have to change my fan resistor + Plug so I have to disconnect my batteries.

 

[Steve V]

Dealer can reprogram HVAC control module,I've done it to a few. There is a bulletin for this I believe.

 

[Turbo Indian]

this just happened to my 06 GMC last friday. I thought it had something to do with my turbo timer. but after about 10 miles it went back to cooling.

 

[jpratt]

Mine just started working again also.