AC compressor switches rapid on-off

GRANDPAMC

MEMBER
1994 BUICK LESABRE
3.8L
6 CYL
2WD
AUTOMATIC
70,000 MILES

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?

Tuesday, October 24th, 2017 AT 4:34 PM

4 Replies

WRENCHTECH

MECHANIC
20,758 POSTS

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.

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Tuesday, October 24th, 2017 AT 5:04 PM

GRANDPAMC

MEMBER
2 POSTS

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.

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Tuesday, October 24th, 2017 AT 5:10 PM

WRENCHTECH

MECHANIC
20,758 POSTS

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.

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Tuesday, October 24th, 2017 AT 5:13 PM

GRANDPAMC