Question about 2009 GMC Acadia
AC is not blowing COLD air. There is an ond and off hissing sound from the center of the dash. I can hear and see the compressor clutch engaging and disengaging. I put a gauge on the freon low pressure side and it goes up and down as the compressor cycles. Using an infrared thermometer gun I tested the vents. When it was 90+ outside the vents were blowing 80 on recirculate & full max cold. When I shut down the cold the air from the vents shot up to 115. I checked later in the day when it was cooler. It was about 75 outside and the vents were blowing 50. So what we have for sure is a system that DOES cool the air is also making a lot of noise inside the car... and a compressor clutch that cycles. I'm buying a high/low ac manifold gauge today. But ahead of that purchase does this sound more LOW freon related..... or THERMAL EXPANSION VALVE.... or something else.
Not sure if I'm too late to answer this one, but you're describing a low refrigerant condition. The hissing noise and constant cycling of the compressor clutch are indicators of that. You should recover the system, record how much refrigerant was recovered, evacuate the system (with a vacuum pump), add A/C dye, and recharge the system to capacity. Common leak areas on these vehicles include the A/C condenser (located in front of the radiator), and the evaporator (located inside the dash, and requires complete removal of the interior dash to replace it). If you can't find a visible leak after running the recharged system with dye for several weeks and it starts to blow warm again, you will need to use an R-134a leak detector to "sniff" areas of the system for a refrigerant leak.
Posted on Oct 19, 2013
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Posted on Jan 02, 2017
yes alow presure switch is likely on GM and it could be out of freon ,safe way to tell is to put a set of gauges on it and it will tell by passing the low side switch will just destroy the compressor if it is out of freon
Posted on Jun 28, 2009
There is only one A/C system split into 2 zones. Check the blend door actuator, it may have failed in one position or something may be jamming it. Also check the control panel in the dash, My 98 yukon did the same thing, no matter what temp you selected for the front it would blow at about 70 degrees. There is a circuit board in the control panel that gets corroded and one of the circuits controls blend door operations. Have a look.
Posted on Jun 12, 2008
Check the magnetic clutch is engaged on front of a/c pump, have the motor running, a/c on and fan on high, if the centre hub is static the pump in not switched on, this can happen when the gas pressure gets low.
Posted on Aug 05, 2009
SOURCE: I have a1998 GMC Z71
You need to remove the dash panel out and check the vents.There is definitely a loose hose or a clog.Fill water from the dash vents and see from where it comes out.If its getting leaked in between then hose is loose there, also if the water is not coming out of end of the pipe then its getting clogged somewhere.The vent duck needs to be cleaned internally and hoses needs to be reconnected tight.Because fan is running properly and all parts are replaced.So the vent duct is getting indicated, its clogged/blocked or loose / cracked.Check it, This will help.Thanks.Helpmech.
Posted on Jun 13, 2011
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