AC compressor switches rapid on-off

1994 BUICK LESABRE
70,000 MILES • 3.8L • 6 CYL • 2WD • AUTOMATIC
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GRANDPAMC
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  • 2 POSTS
Blowing cold air, but AC compressor cycles on/off rapidly. AC shop says Freon is correct. Mainly problem is in moderate outdoor temperatures. Should I consider a relay somewhere is malfunctioning?
Oct 24, 2017 at 4:34 PM
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WRENCHTECH
  • ✓ASE Certified Mechanic
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  • ASE Certified Mechanic
This is probably cycling due to low refrigerant pressures. This could be normal as the pressures will drop in lower temperatures and even further if the blower speed is lowered. It is a cycling system by design.
Oct 24, 2017 at 5:04 PM
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GRANDPAMC
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AC tech says pressure is fine and Freon level is good. Is it possible pressure switch or relay switch is bad? This is all original equipment with only 70,000 miles. Or maybe I need a new AC Tech! When they were checking it, the recycling was not happening at idle.
Oct 24, 2017 at 5:10 PM
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WRENCHTECH
  • ✓ASE Certified Mechanic
  • 20,761 POSTS
  • ASE Certified Mechanic
I did not say there was anything wrong. It is a cycling system by design and it is supposed to cycle at a specific pressure and colder temperatures and low blower speeds will bring it down to that temperature.

PS, unless your mechanic completely evacuated the system and recharged it with the measured amount of refrigerant, he cannot know if it has the correct amount.
Oct 24, 2017 at 5:13 PM
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GRANDPAMC
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Thanks.
Oct 24, 2017 at 5:15 PM
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