AC ice cold at idle warm when driving


Old 07-17-15, 03:26 PM
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Join Date: Jul 2015
Location: USA
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AC ice cold at idle warm when driving

I have a 2003 Buick Regal GS. Out of the blue it started blowing warm air. I hadn't added any freon in a while so I added a can. When that didn't work I added a second can with no luck. I put a set of gauges on it and this is what I got.
I turned the AC on max cool with the blower on high, the Recirc on and the windows open. At 75 degrees idling at about 1200 rpm I got about 35 PSI on the low side and about 165 PSI on the high side. Under these conditions it blows ice cold air. As soon as I start driving the air gets warm.
So I put the gauges back on and fed the lines and gauges thru the drivers window. When driving at about 45 mph the engine runs at around 1600 rpm. Under these conditions the low pressure climbed to about 65 PSI and the high pressure dropped to about 90 PSI. As soon as I let up on the gas to coast it dropped back down to 35 PSI Low and 165 PSI High and air got ice cold. It ran this way most of my test drive. To get back to my house I have to climb a long steep hill. When climbing the hill the low pressure climbed to almost 90 PSI and the high pressure dropped to about 80 PSI.
I have read different things from orifice tube to evaporator valve. Any help on diagnosing this problem would be appreciated.

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Old 07-17-15, 06:48 PM
ukrbyk's Avatar
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Location: USA/ Pacific NW
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Old 07-21-15, 10:33 PM
Join Date: Jan 2006
Location: Ontario, Canada
Posts: 759
Do you know if you have any vacuum operation on Heater/AC control? Some did, so thought I'd better ask that first. Would explain change on acceleration or under load, as in going up a hill. If blend/air door is vacuum operated, that may explain the change in temperature.

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