what would make the A.C compresser frost over when not being used on 1993 GMC Sonoma

it is on a 93 gmc sonoma i am in the the proses of replacing the heater core and was wondering why the A.C compresser was frosted over after driveing but not useing the ac

by in Murfreesboro, TN on October 30, 2011
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1 answer
ANSWER by , October 30, 2011
If you are using the defrost, then the A/C compressor is still working. Are you using defrost at all?