Auto A/C question.

My A/C compressor is cycling on/of about every 40-50 seconds. the dash control is set fot heat. It’s a '96 Cherokee. I’m going to take it to a shop, but I’d like to know probable causes so I can try to avoid getting skinned.
BTW, I put my hand on the back of the unit and can feel it immediately get colder when it kicks in, so I’m sure it’s the compressor.

Is the defroster on?

You know, it might have been. I’ll have to run it again, making sure the defrost is off, and repost. Thanks.

Even if the defroster is on, I don’t think it’s supposed to cycle like that. It could be low on freon.