A/C compressor won’t engage

[TJScott]

I have a 2003 Sport 4.0. The compressor won’t engage. Blower motor is working fine. I’ve been searching around and one consensus is the Freon may be low. But, can you add it to the system when the compressor isn’t operating? I was thinking a little at a time until the compressor started to kick in? I don’t use it a lot in the winter. But, do remember using it a month or so ago to de-fog the windows. Do the TJ’s use the current iteration of Freon? Is it possible a fuse has popped? If so, anyone know which number it is?


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[lafittejeep]

My problem is my compressor doesn't shut off. Lines ice up when my inside switch is off. My coolant is fine and I think its my climate switch controls. Just need to change my switch or switches.

 

[Steel City 06]

Yes, you can add some refrigerant while the compressor is not engaged.

Make sure the A/C is turned on so it can engage once the low pressure signal is turned off.

Take your time and fill slowly. If you send a slug of liquid refrigerant into the compressor it will blow up the compressor (I’ve done it).

If your low side refrigerant charge reaches a normal value without the compressor engaging, it could be several things causing an issue. It could be low pressure or high pressure switches, a bad clutch, a blown fuse, or another wiring problem.

Before starting double check the fuse for the A/C clutch.

I believe the TJs use R134A. Do not use R410A or R22.

 

[Steel City 06]

My problem is my compressor doesn't shut off. Lines ice up when my inside switch is off. My coolant is fine and I think its my climate switch controls. Just need to change my switch or switches.

Do you have the defroster engaged? The defroster will turn on the AC to dehumidify the air.

It’s possible your low pressure switch is bad, which is allowing the ice build up.

If you aren’t using the AC for an extended period you could simply pull the fuse.

Also, the clutch could be trashed on your compressor. With the engine off, remove the serpentine belt from the AC compressor, pull the fuse, and spin the compressor pulley by hand. The pulley should spin freely and not turn anything in the compressor itself. If it turns with significant resistance (turning the compressor internals), then the clutch is toast.

 

[Jerry Bransford]

If your compressor ends up being low on or empty of its refrigerant, you very likely (pretty much guaranteed) have a leak in the A/C system. They don't consume refrigerant, it should stay full unless there's a leak. So if it's low, there's a process that should be followed to refill it which is best done by an a/c technician. They will use a dye to find the leak so it can be repaired.

 

[TJScott]

Thank you guys so much for the info. I will try and slowly add to it and see if it kicks on the compressor. If so, I will fill it and see what happens. Sadly, the only mechanic I trust is a 1/2 hour away and open the same hours I work. But, if this turns out to act like a leak, I will get it to him some how. I haven’t touched the A/C on this since I bought it 3 years ago and it now has 90k on it. Not sure what prior maintenance was done in the area of the A/C. But, I am not doing summer in the high desert without A/C.


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[lafittejeep]

Do you have the defroster engaged? The defroster will turn on the AC to dehumidify the air.

It’s possible your low pressure switch is bad, which is allowing the ice build up.

If you aren’t using the AC for an extended period you could simply pull the fuse.

Also, the clutch could be trashed on your compressor. With the engine off, remove the serpentine belt from the AC compressor, pull the fuse, and spin the compressor pulley by hand. The pulley should spin freely and not turn anything in the compressor itself. If it turns with significant resistance (turning the compressor internals), then the clutch is toast.
[/QUOTE/
Nothing on control wise. All knobs at 7 o'clock position. Had AC friend to check pressures and amount of coolant and all normal. With relay in clutch does cycle on and off as usual but when I turn everything off inside ac clutch still cycling and you can watch everything start to freeze up. Taking out climate control switches to check them out.

 

[TJScott]

As a follow up. I went and bought Freon today. The can with the gauge on it. I kept putting in a little at a time while idling with the A/C on full. It slowly started kicking on then off. The duration on got to a point where it was longer, though not long, just the frequency of on got better. The air is coming out cold. I’ve never really thought about how long the compressor stays on during idle before. It’s really not long. Unless I have another issue. It seems like it’s only a few seconds or so. I always thought it was on during the time you were using A/C. Any thoughts on the amount of time that compressor normally stays on before going off again?


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[Steel City 06]

At 72 plus degrees and with the AC on full blast, the compressor should not cycle up until around 1000-2000 engine RPM or even higher depending upon the manufacturer’s specifications.

If filled to the specifications on the provided gage it should not cycle. Those gages aren’t the best way to do it (professionals monitor both the high and low side pressures when filling), but they are a decent estimator.

The system is likely underfilled, but it could also be overfilled. There is a high pressure cut off switch that turns the compressor off if the high side exceeds a set pressure limit.

If you can’t seem to get the right charge, take it to a professional. You might be leaking refrigerant at a rapid rate. (Technically, knowingly filling a leaking system is illegal.)