Today my coworker informed me that my belt is squeaking again.... So I assumed that harmonic balancer came off and hitting my fan. When I popped the hood I saw that the AC clutch is engaged, even though it is turned off. In fact the **** is turned to defrost... Why is it engaged when it's obviously not switched in the cabin? And I have to say, it's really loud. I pulled the fuse off for now. Hmmm 1999 cherokee 4.0

Is there a short somewhere or faulty compressor?

 

It will be when set to defrost.
Change to heat and it should click off..

 

If the ambient temp is over 30* the compressor will cycle when defrost is selected. Heat or "O" (which is off)

 

It is designed to cycle on and off when you have the ac or the defroster in on. There is nothing wrong other then it is making a lot of noise. Is the compressor make the noise or is the belt? If it's the belt you may either need to tighten the belt or replace it if it is glazed or cracking.
BTW, It doesn't matter what the ambient temp is. If it set to defrost it will still cycle.

 

It's brand new belt, and yes it is loud to me, (I really don't know what sound it is supposed to make though, I'm deaf)

But I can hear like metal hitting metal kind of sound. Sort like rattling. The sounds occur only when the clutch is engaged and stops when it's disengaged

 

Sounds like the bearing is going out. Had that happen a few years ago.
It got sounding pretty nasty.....

 

All do respect, I beg to differ.

 

[QUOTE=BTW, It doesn't matter what the ambient temp is. If it set to defrost it will still cycle.[/QUOTE]

Not correct.

The low pressure cycling clutch switch contacts are
open when the suction pressure is approximately 141
kPa (20.5 psi) or lower. The switch contacts will close
when the suction pressure rises to approximately 234
to 262 kPa (34 to 38 psi) or above. Lower ambient
temperatures, below approximately -1° C (30° F), will
also cause the switch contacts to open. This is due to
the pressure/temperature relationship of the refrigerant
in the system.
From FSM.

 

thank you prcherokee.

I can also vouch for this as it's been in the 20's at best. The rare day or two it got over 30* my IAC ws sluggish at cold idle, and I'm like WTF? And then realize, oh yeah, the compressor is actually on because it's warm enough. lol

 

Alright interesting. I never knew it still would engage. I ll try to make a video with the sound. Maybe you guys can decipher it.

 

Allready got your answer here ...

 

Yeah I know, I saw that and I wanted to make sure. Cause sometimes I hear sounds differently than what it sounds to others.

 

I'd take the belt off and check all the pulleys to make sure that they all rotate freely. I had a "rattling" noise and it turned out to be the bearings in the idler pulley. Checking them all will narrow it down.