Automotive Air Conditioning Information Forum

Ac does not blow as cold as it did 3 weeks ago. Gauges were showing H - 225 L 25-20 with ac clutch engaged . when it disengaged it dropped to H 150 then 125 and stayed at L 40 According to a chart I found those numbers were low . I put a can of 134 in .

After that I turned the engine of and restarted the car . Now we started at 40 low dropping to 35-30 and then 25 . High started at 225 and then 215 - 200 as it kept running . The ac clutch did not disengage at all.
The ambient temp was 94 and the temp coming from the vents was 85* . I also tried the blend door r-set as shown on Sparky's .

The supply line from the compressor is cool to the touch. Low pressure section of the line is also. Hp side of the line is hot . The Accumulator is also.

Yesterday we had slightly cooler air coming out of the vent , but at a stop sign it become warmer . No fan clutch. Two electric fans .

It has dual electronic temp control . all vent selection functions seem to work as the should . The catch is that the blower speed selections show on the readout as they should . The blower speed does not always . match the readout . It may be stuck on low . Drive a while turn engine off and the go again and it works as it should. As I have messed with it in the driveway it will sometimes correct itself if I mess with Auto select button.

Sorry to be so long but I wanted to give as much info as possible . I am stumped and wife is grouchy with no AC in 95* temps . I told her to toughen up ! Thank you for your help .

I sure hope that the can you put in was only R134a and did not contain ANY sealer, that could kill the system.

I have a 2005 Denali. Sounds to me like you have a refrigerant leak, need to have a real AC shop look at this and measure the refrigerant in it by weight. And pinpoint and/or fix the leak. The AC in our 2005 Denali works very well, but in Phoenix and now 193K on it, I did replace its compressor once.

Are your low and high pressure readings taken at about 1500 rpm?

Yes , only freon . no sealer . Those readings were at idle

Cusser wrote:Are your low and high pressure readings taken at about 1500 rpm?

Need pressures read at that rpm after a couple of minutes. I suspect that you're still low on R134a. High pressures typically get to 260-280 psi. With the dual air system, more refrigerant required than with front-only.

Have not checked again with the gauges .still need to go get them again , but found out this week that the rear works as it should.front does not . With the blower control on high there hardly any air movement.

Check the front blower fan for operation. Also there are like three solenoid valves under the dash that direct the air flow, maybe the air is being directed to the windshield (defrost) or under the dash (heat).

I guess another issue could be a clogged cabin filter (if your 2006 has one) or debris in the pathway or clogged surface of front evaporator.

cusser , thank you . Now it seems the front blower is not working at all . The small amount of air coming out is cool and does change temp when the dash gauge is adjusted . Blower speed does not change at all . When this started the blower was working on all speeds , then it was intermittent . Sometimes would be set on hi , but speed would be low to medium and then would fix its self to match dash . sometimes if you would turn ignition off for a few minutes and do it again it would be ok .

When you can't actually change the fan speed on it, the blower speed module is done. It gave you a couple of warnings, now it is failed completely.

The auto climate units use a solid state control instead of a resistor, but it is located in the same place.

Thank you .. I pulled the module today as well as the blower . 12v and the blower worked fine . It there any one brand or place that may be better than the other to get the module ? This one is the 3530 3 wires and the black and purple wire .