Question about 2003 GMC Yukon

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A/C blowing hot air. Compressor activates and system has pressure.

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  • Anonymous Feb 18, 2009

    my a c compressor is working but the air inside the truck is hot like the heater would be on.

  • srgarrett21 May 11, 2010

    The condenser is under the hood, the evaporator is in yur dash.

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Could be the expansion valve. That's what allows the temperature to actually drop in the system - the contents of the AC system are under pressure, and are at a certain temperature. When the freon goes through the expansion valve, the pressure drops suddenly and dramatically, which "flash chills" the freon, allowing the air to blow cold. If it fails, you may get lukewarm air from the AC despite everything else working. Also though, check to see whether the AC evaporator fan (underhood) is working - on some cars, if it doesn't turn on, the compressor won't be run enough to cool the air.

Posted on Jul 29, 2008

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Just wondering how long ago did your problem start was ac working normal as the other tech said low freon if the system has trapped condensation and air should be dryed refilled

Posted on Sep 11, 2008

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You are probably low on freon. Usually when your a/c unit is low on freon, the compressor will kick off, but, your car may not do that. You can have it the freon checked at any local repair shop. I have a '99 S10 blazer, and my compressor won't even kick on, so I know that the compressor is bad.

Posted on Jul 29, 2008

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wildboy8521
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SOURCE: blowin hot air system pressure way to high

Too much pressure in the ac system is just as bad as not enough pressure... to much pressure can actually stop the ac compressor clutch to not be able to disengage therefore ending up burning out the compressor... start off with checking if the compressor is engaging then if it is bleed off some of the pressure until its in the proper range... if that still doesn't solve the issue you may have some moisture in the system and will therefore need to have the whole system vacuumed out and replace the drier then recharge the system.

Posted on Feb 27, 2013

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see this causes and fix it. God bless you
Compressor Checks
checkmark.gif Start with the compressor. Does it engage when you turn on the A/C?
If so, the compressor is working and the A/C system probably contains enough refrigerant to make cold air, so the problem is inside the HVAC unit. Replace the motor that controls the blend air door (this is a difficult job and best left to a professional since it involves tearing apart the HVAC unit -- about an 8 to 10 hour job!).
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If the compressor does not engage when you jump it, the problem is a bad compressor clutch.
If the clutch engages but the compressor does not turn (the belt will start to slip and squeal), the compressor is locked up and you need a new compressor.
If the compressor clutch engages and turns the compressor, but the A/C still does not blow cold air, the system is probably low on refrigerant and needs to be recharged.
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checkmark.gif Connect an A/C pressure gauge to the HIGH SIDE service port (located in the high pressure hose that runs between the compressor and the condenser in the front of the engine compartment). The gauge will tell you if there is any pressure in the system. Simply depressing the service fitting valve with a small screwdriver to see if any refrigerant squirts out is NOT an accurate check because it tell you how much pressure is in the system. It may still have some pressure but not enough to trip the low pressure safety switch so the compressor will engage.
If your A/C system is low or out of refrigerant, check for leaks, then have the A/C system vacuum purged to remove air. After the air is out, it can be recharged with the specified amount of refrigerant. It is important to get any air out as this will reduce cooling efficiency and may make the compressor noisy.
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checkmark.gif If the refrigeration circuit seems to be working (refrigerant in the system, compressor running and building pressure), but there is still no cooling, the problem might be an obstruction in the orifice tube (located in the high pressure hose between the condenser in the front of the radiator, and the evaporator located in the passenger compartment). A blockage here will prevent the refrigerant from entering the evaporator or recirculating through the refrigeration circuit.
If the orifice tube is plugged, the high side pressure reading will be lower than normal, and the low side reading will also be lower than normal because no refrigerant is circulating through the system.
checkmark.gif If the refrigeration circuit seems to be functioning normally (compressor running, frost or condensation on the high pressure line from the condenser to the evaporator), but no cool air is blowing out of the ducts inside the car (and the blower is working), the fault is likely a BLEND AIR door that is stuck in the HEAT position, or possibly a badly clogged cabin air filter that is restricting airflow. Another possibility would be a fault in the automatic climate control system such as a ad interior temperature sensor or control module.

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