Jeep Cherokee Forum - Should A/C compressor engage for heat?

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Peter1969

04-01-2018 07:44 PM

Should A/C compressor engage for heat?

2000 gc. Just replaced accumulator with hoses, then had it evac/press tested and charged at mechanics. Noticed the compressor kicks on for heating. Didn’t think this is right, but I don’t fully understand the chemistry involved with hvac. Did note that if air selector is set to floor only the compressor goes off when heating. If left on auto or the other settings and heating the compressor comes on. Stumped/scratching head. Lol Any answers would be greatly appreciated, as the ole dog needs to put this as a completed fix. Happy Easter!!

00t444e

04-01-2018 08:26 PM

The compressor should come on in any of the defrost modes.

dave1123

04-02-2018 07:15 AM

There's really no need for it to come on, but it does. When A/C first was installed in cars, people never used it all winter, as expected. Without cycling, the seals dry up and the freon leaks out so it had to be recharged every spring. Auto manufacturers decided to have the compressor cycle every time you used defrost to eliminate this problem.

Peter1969

04-02-2018 08:59 AM

Thanks Dave! No it doesn’t make sense, but I get it. Had a 99’ Taurus and usually left it on auto, even changed the compressor on it. No telling how many mpg was lost to it coming on. Though in lower Alabama the heat function is hardly used. Thanks again! Get to check off the A/C as repaired and ready for the hot weather

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