AC Question

[DHicks]

My AC blows warm air when the car is stopped at idle, but when I speed up the air cools down. This was verified and the shop that did the AC Recharge after I complained about the air temp. The shop thinks the compressor is going and wants to charge me $1200 bucks to fix it. I was wondering if anyone else has experienced this and what the possible solutions are. Thanks for your time!

 

[joegr]

What year is your LS? If it is a gen I, it has a hydraulic cooling fan. Sometimes those fail, and when they do, one symptom would be poor AC at idle. Another possibility is that your compressor is failing, like they said.

 

[DHicks]

It's an 05 V8

 

[joegr]

It's an 05 V8

Could be the compressor. Did they do any pressure tests?

 

[DHicks]

No, they just shot a laser temp gauge at the air vent. I need the have the car lined up anyway, so I will have them do a pressure check too.

 

[stihlboy]

Dccv does that too

 

[joegr]

Dccv does that too

The DCCV causes AC problems, but generally not his symptom. It would get worse at speed, not better.

They need to do the pressure tests. Otherwise, it's impossible to tell if it is the compressor or the expansion valve. (Even with the readings, it's still a bit of a guess.)

 

[stihlboy]

The DCCV causes AC problems, but generally not his symptom. It would get worse at speed, not better.

They need to do the pressure tests. Otherwise, it's impossible to tell if it is the compressor or the expansion valve. (Even with the readings, it's still a bit of a guess.)

True, my car was low on r134a and did this, the heater door actuator could have it slightly warm at idle, and excessive clearances in the compressor can do it as well... I have seen all the above on these cars...

Joegr: you're right mine got hot at speed cold at idle with the dccv

 

[joegr]

... the heater door actuator could have it slightly warm at idle...

I respond to this because I see it a lot. Most cars have one or more air temperature blend doors (aka heater door actuator), but the LS does not*. It's a misunderstanding that gets in the way of correctly diagnosing problems with the LS. The LS uses only water flow control (via the DCCV) to set air temperature, instead of air flow control.

*: The 1st gen LS does have a "cold air bypass door." It does not control air temperature, other than it completely bypasses the heater cores when maximum cooling is called for. On a 1st gen with a failed DCCV, you can get cold air by setting the temp to 60, but you won't be able to control the temperature.