QuestionI have a 2000 Jeep Cherokee and when the heater is in the defrost position the air condition compressor cycles when the engine idles,is this normal? I noticed this today when the outside temp was 22F.
AnswerSabatino,
Absolutely this is normal. The reason for this....
Around the compressor shaft there is a bellows-type seal. The primary reason for this seal is to keep the oil from leaking out of the compressor (like a rear main on an engine) However, being that the refrigerant inside the system mixes with the oil in the compressor, it is especially vital that it remains in good condition.
If you leave anything made of rubber set for an extended period of time it will dry-rot and crack. If this seal happens to dryrot, out goes your refrigerant and here come more problems. So, to prevent this the automakers decided that the easiest way to keep this seal lubricated and in good condition during the winter months, in which it would never be turned on otherwise, is to have the compressor engage whenever the heater is in the defrost mode. Most people do not use this as a primary source of heat, but do use it often enough to defog their windows during the winter. So it saves the seal, without having it run constantly.
I thank you for your question, and hope I was of a little assistance. If I can do anything further now or in the future, please do not hesitate to ask. If you found this answer helpful, please remember to rate it. Thank you again and good luck in everything.
