I have a 99 xj 4.0. I noticed about a month ago that every time I drive it the a/c compressor cycles about every 20 seconds for about 4 seconds. It doesnt matter where the controls are, what the ambient temp is, or what driving conditions. I noticed it wasnt real cold last summer and put in some refrigerant. It leaked in about a week so I put in some sealant that I was told will fix almost any leak. During the winter I didnt notice the cycling issue, perhaps because I was running it off the cat. I tried it this summer and get warm air and the pump just does the same quick cycles as it does when i have it set to the heat settings. I have some theoretical knowledge of how the system works but I am clueless on what type of switches or sensors would cause this. Any help would be great!

 

its still leaking ,top the freon off have it checked and fix the leak 99 percent of the time sealer does not work

 

There are 5 selector positions that engage the compressor (yellow circles) and 2 positions where the compressor is not engaged. As mentioned, u probably still have a refrigerant leak, the system is low.

 

Inject dye into the system and fill with the proper amount of 134a.
Drive it and use the A/C for a week and then check all of the hoses, Compressor and condenser with a black light for signs of refigerant dye. If none detected then you will have to check the evaporator located behind the dash.

 

Thanks for the advice! I pulled the relay for now just so it doesnt cycle all the time. I read some other posts that said to get a free estimate from a repair place so thats probably what I will do. Now to search for the cause of a quiet grinding at low speed...

 

I have a similar problem where the AC keeps cycling the compressor. Seems to cycle on/off every 5-6 seconds.

The system works reasonably well, so it does cool. But I thought it wasn't that great compared to my other cars, but then again, I'm not sure how efficient the AC is supposed to be

So I bought one of these refill cans with a gauge. When I hooked it up it showed sufficient filling.

I guess some cycling is normal, or am I mistaken? What are the condition under which the compressor would run constant.

Anybody with some further insights on how the AC system works as far as the compresso on/off switching is concerned?

Jeroen