JeepMoreDoor

I have a 2000 xj and just installed a new compressor and flushed and charged the ac system. If everyone's familiar switch the settings **** the right side with white logos is the heater settings. When I set to windshield defrost it blows hot BUT I can hear the compressor engaging. ??? To make sure I opened the hood and yes it's engaging. I don't think it's ever done that with the original compressor so I am wondering why now? Please help me out here. Ask questions if needed.

djb383

There's not really a heater setting, but rather a vent selection setting (windshield, dash, floor). There are 5 vent positions in which the a/c compressor is engaged and 2 (uncircled) positions in which the compressor is NOT engaged. Turning the temp selector will add (more or less) heated air to the system, regardless of where the vent selector is set.

JeepMoreDoor

djb383: ok I just assumed that since the white settings didn't have a snowflake that the compressor would not be engaged. That would be great to rig up a way to disengage the compressor with a button. So what's the aftermarket button you circled in red for if you don't mind?

djb383

When the selector is in the windshield position and the temp selector is to the left, the compressor engages to send cool/dry air to the glass to defog/remove moisture from the inside glass in warm/humid weather conditions. In freezing weather, selecting the windshield position and moving the temp selector to the right will de-ice the outside of the windshield.

Our XJ is a base SE model, no power anything. That switch and servos in the doors and tailgate were add by the PO. Not keyless remote, but makes it easy to lock/unlock everything from the drivers seat.

macgyver35

Yes, you'll see that the compressor engages when you use the defrosters.

In actuality, there are two reasons for this. First, having the compressor kick on allows the incoming air to pass over the cold coils first and be dehumidified, thus speeding up the defog process. Two, having the compressor engage occasionally during the cold months keeps everything in the compressor lubed up and working freely. In some parts of the country, AC is only needed for a 3 or 4 months a year, and having the system sit that long unused is not good for it.