AC - Weird symptoms...??

[OR VietVet]

If you are going by a cool feel just with your hands/skin then what I about to say may not mean much to you. If the fan/blower speed is at the higher speeds, the air blowing out will actually be a slight bit warmer than when the blower is at lower speeds. You can use a thermometer or infrared temp gun and verify what I am saying. Once the system has been running for about 5 minutes, measure the temp at high fan and then at low fan speed and see the temp drop at the lower speed.

 

[djfell80]

So, realized this afternoon: first start truck and it takes a minute for the compressor to kick on. Then it cycles on and off for a long time, bareley cooling anything at all. Then after a few minutes it finally stays on and begins to cool (while sitting still). Then once you start driving (low speeds, around the neighborhood) it begins to warm again. Rear AC definitely cools much better than the front. 50ish/250ish are the pressures when it stays on at idle. low psi line is cold, and high side is hot. Guess I will be tearing the dash apart and just replacing everything in it: remaining actuators, temp sensor, etc. May just install a window unit on the rear windows and my genny on the roof. Should be ok...

 

[rockola1971]

Did you weigh in the refrigerant to what the underhood label says? It sounds like you are either overcharged or possibly undercharged. You state pressures are 50/250 but those numbers mean almost nothing without ambient outside temperature since the pressure of the refrigerant is directly proportional to the ambient temp. You could also have the front blend door stuck toward heat position. Cycle your front HVAC to heat and then switch to a/c to test. You should be able to hear blend door switch. Verify compressor clutch is not slipping and/or disengaging when its not suppose to be. You will need a scanner to verify call for clutch on signal and you can manually test the clutch with the scanner too.

 

[2006Tahoe2WD]

In the past the blend door or one of those doors went bad and the AC would not work. I paid to have a mechanic change the actuator because it involved removing the dash/etc.

 

[djfell80]

Changed actuator and works 95% of the time now. However, works great in the morning after sitting in the garage. But my wife says it most of the times doesn’t work after sitting at her work outside all day.

 

[2006Tahoe2WD]

It would be nice if someone would list what the various doors/actuators do and where they are located. I guess I could google it.

 

[2006Tahoe2WD]

After some digging around with Google it looks like there are 3 or 4 doors/actuators.

 

[rockola1971]

After some digging around with Google it looks like there are 3 or 4 doors/actuators.

Get a free autozone online account and then you can access for free all the electrical diagrams, parts locators, test procedures and much more.

 

[2006Tahoe2WD]

Get a free autozone online account and then you can access for free all the electrical diagrams, parts locators, test procedures and much more.

okay I'll check it out. Thanks.

 

[djfell80]

Update: finally took to shop, found the main fuse block was bad. Replaced with OEM from dealer. AC works great now. Geez! Crazy stuff.