91 AC Issues - programmer help
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Joined: Apr 2007
Posts: 98
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From: Knoxville TN
91 AC Issues - programmer help
I've been having some issues with the AC on my '91 coupe. At first I thought the freon was low but after having it checked, it's right where it needs to be. The issue was that the compressor was still not kicking on, then after repeated tests, it was kicking on about half the time. We replaced the cycling switch and low and behold, the compressor kicks on fine. Now the issue is that when in auto mode, the compressor won't kick out - even when we turn the temp way up. The blower doors switch to the floor but the compressor keeps running. Now, in any other mode, the compressor behaves.
So we've determined the issue must be with the heater/AC programmer that lives up under the dash and is supposedly a fun replacement. The issue is that I can't seem to find a replacement for a '91. Corvette Central offers a rebuild service but other than that, I'm striking out. Any suggestions? Thx.
So we've determined the issue must be with the heater/AC programmer that lives up under the dash and is supposedly a fun replacement. The issue is that I can't seem to find a replacement for a '91. Corvette Central offers a rebuild service but other than that, I'm striking out. Any suggestions? Thx.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
That's normal. Auto Heat still uses the compressor to dehumidfy the air. It's also used for Defrost and Bi-Level. In fact, pretty much everything except the Economy setting - see your Owner's Manual.
Whether or not the compressor cycles is a function of charge/pressure and ambient air temp. The Low Pressure Switch opens the relay ground at 25 psi and recloses at 50 psi. Specs are 8 cycles or less per minute at 70 degrees. Realistically, a fully charged system shouldn't cycle until it's about 50 degrees, at which point, it may be off more than it's on until engine heat warms it up.
Whether or not the compressor cycles is a function of charge/pressure and ambient air temp. The Low Pressure Switch opens the relay ground at 25 psi and recloses at 50 psi. Specs are 8 cycles or less per minute at 70 degrees. Realistically, a fully charged system shouldn't cycle until it's about 50 degrees, at which point, it may be off more than it's on until engine heat warms it up.
