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04 AV AC not working

zman537

Full Member
Joined
Aug 8, 2018
Messages
9
Hey this is my first post, I have done every search on this forum, and when I  think I found the solution I run to the parts store and buy the part but no victory.
I have a 2004 AV that all the sudden started blowing hot air. I shut the truck off and started it again which seemed to work for about 10 min then right back to hot air.
The clutch is engaging, The line are cold, water is dripping out of that drainage hose from the fire well, so it isnt plugged.

Here is a list of things I have done:
Charged with R134 from autozone- It did read low on the gauge- I followed the direction on the can, still no changes.
Replaced Cycle switch with brand new one- still no change.
I replaced both Door blend actuators, so yes I tore dash apart and replaced the one up top, and the one down by the feet on the passenger side - no change
I did find a walk through on how to recalibrate or reset the door blend actuators by turn on, pushing auto on the control head then removing the HVAC-ESC fuse and plugging it back and then turning truck on. the truck goes through the recalibrate and you can hear the doors open and close. but still no Cold air. The buttons on the control head work, so I can switch between dash vent, floor vents and main vents without any issues.

I checked all the fuses- nothing is blown.

I have spent about 300 dollars so far and cut up every finger I have tearing apart that stupid dash. I dont know what to do next.

:help:




 
How about the air temp sensor?
Assuming you have climate control the sensor is what everything is controlling to.  If the system thinks it's cold..... well..... let's crank up the heat!!

The monkeys at the dealership inadvertently disconnected the sensor in our Z71 and it would turn the truck into a meat locker.
 
When you do the reset by pulling the fuse under the hood,,, Are you starting it and not touching it for a few minutes to let it go through it's full process?
 
Big Blockhead said:
How about the air temp sensor?
Assuming you have climate control the sensor is what everything is controlling to.  If the system thinks it's cold..... well..... let's crank up the heat!!

The monkeys at the dealership inadvertently disconnected the sensor in our Z71 and it would turn the truck into a meat locker.

So I may have to buy the control head?? I was hoping someone has a cheaper idea.
 
ohiobellboy said:
When you do the reset by pulling the fuse under the hood,,, Are you starting it and not touching it for a few minutes to let it go through it's full process?
[/quote

Yes I let it go for about 4 minutes and didn't touch a thing. It goes through the reset process. But still doesn't blow the cold air
 
Was the battery dead or disconnected when this started?
 
MS03 2500 said:
Was the battery dead or disconnected when this started?
Nope I had been driving that day for about an hour. No disconnect from battery or dead battery prior to driving
 
Big Blockhead said:
How about the air temp sensor?
Assuming you have climate control the sensor is what everything is controlling to.  If the system thinks it's cold..... well..... let's crank up the heat!!

The monkeys at the dealership inadvertently disconnected the sensor in our Z71 and it would turn the truck into a meat locker.

Ok, so I tried a YouTube search, couldn't find one for the avalanche, but where is this located
 
Also I noticed that I really don't have any temperature change at all when I switch it to heat. So I guess this does
sound like the control head I guess????
 
Is your voltage reading ok? Alternator working fine? The resistor for the AC, is it old? If its auto climate control, these resistors are notorious for going out. Happened to me.
 
Ok so I found a sensor in the headliner above the driver's side. I don't have any temperature difference at all when I change from hot to cold. When I unplugged this sensor I all the sudden had hot air, but still no ac. Could it be that sensor. I feel like I'm just gonna throw money at this thing until I find it.
 
Raiders91340 said:
Is your voltage reading ok? Alternator working fine? The resistor for the AC, is it old? If its auto climate control, these resistors are notorious for going out. Happened to me.

That actually happened in my trailblazer, but the fan stopped working when it went out. The fan speed still works on the avalanche, so does the resister also have to do with hot and cold? I haven't checked the alternator.
 
You could do the simple thing and take it to a mechanic that deals with AC stuff.. they will likely find the issue in less than a half hour and charge you less than the next part you change that wasn't it....

Rodney
 
redheadedrod said:
You could do the simple thing and take it to a mechanic that deals with AC stuff.. they will likely find the issue in less than a half hour and charge you less than the next part you change that wasn't it....

Rodney
well your right i guess we should just shut this forum down and everyone just go take every vehicle they have to a mechanic instead of trying to do something yourself.  :beating:. well i did that today. 120 dollars later, still the same issue, the AC was 1 pound short, no leaks. he spent over an hour trying to find out what the issue is., he vacuumed everything out. recharged it we drove it up and down the road for 30 minutes, and still same problem.  anyone else have an Idea? its only cooling to 80 degrees.

So I currently have,
2 new blend door actuators
1 new cycle switch
1 new cabin temperature sensor
1 New Automatic AC control head from AC Delco -
Drained and recharged and tested by a mechanic.
Battery and Alternator were checked and good as well.
Clutch is engaging and lines everything to the ac are cold.
Did all the reprogramming.
 
This may just be a total crap shoot, and I apologize in advance if it is, I was just checking GM Parts Direct and it references three different sensors related to the HVAC system.  There's the one you replaced which is over the driver's head.  The sensor for the automatic headlights - the sunload sensor https://www.gmpartsdirect.com/oem-parts/gm-sensor-13498958/?c=Zz1odmFjJnM9YXV0b21hdGljLXRlbXBlcmF0dXJlLWNvbnRyb2xzJmk9SUswNzMxMDUmcj0mYT1jaGV2cm9sZXQmbz1hdmFsYW5jaGUtMTUwMCZ5PTIwMDMmdD16NzEmZT01LTNsLXY4LWdhcw%3D%3D This is the little ball in the middle of the dash. 

Then there's this sensor which looks like it might measure the temperature coming out of the system, but I can't tell for sure https://www.gmpartsdirect.com/oem-parts/gm-sensor-12160947/?c=Zz1odmFjJnM9YXV0b21hdGljLXRlbXBlcmF0dXJlLWNvbnRyb2xzJmk9R1AwMzM3MDUmcj0mYT1jaGV2cm9sZXQmbz1hdmFsYW5jaGUtMTUwMCZ5PTIwMDMmdD16NzEmZT01LTNsLXY4LWdhcw%3D%3D

 
Well the procedure you are using to recalibrate the door I have not heard of before.

So in the GM service manual says.

1. Turn off the HVAC system(No Display), close the sunroof if you have one and turn off the radio. Turn off the truck
2. Disconnect the battery cable for a 10-15 minutes
3. Reconnect the battery
4. Start the engine (Do not touch the control unit for 2-3 minutes)

When you turn it off it will park the doors in their default position and when you turn the truck back on the system expects them in the default position and will cycle them full travel then position them in the proper position.

If you try this remember it will recalibrate the ECM also so it will run rough for a couple of minutes till it relearns the engine sensors.

Good luck.

 
 
^^ This procedure has always worked for me.

My A/C has been known to mess up whenever I had disconnected the battery for some reason or another without first turning the A/C completely off before disconnecting the battery.

My sunroof always has to relearn it's full range of open and closed after the battery has been disconnected, as well.
 
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