A few questions...
Thread Starter
CF Veteran
Joined: Oct 2009
Posts: 2,867
Likes: 16
From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
Hey everyone. I just have a few quick questions.
1) It appears that my A/C compressor isn't cycling. Now, my A/C has never worked in the aspect of blowing cold air, however my compressor has always cut on when I either put the HVAC control on any of the A/C settings or on Defrost. I am getting neither, and I think since the compressor isn't engaging my stock e-fan isn't turning on either. Could this simply be a relay?
2) Where is somewhere in the engine bay I can get 12v power ONLY when the key is turned to "ON"? I need a power source for my e-fan conversion to the switch (fan has constant 12v from the battery to relay, the switch is the 12v when on only).
3) Can the little nub on the mech fan pulley be cut off? I'm talking about the little bit that sticks out past the actual mounting face. I think it is going to hit my e-fan.
4) How many amps is the stock cigarette lighter outlet? I have two 12v outlets I want to install in the ashtray and need a good 12v source to use.. and since I don't use the lighter and I think it only works when the key is on...
Thanks everyone!
1) It appears that my A/C compressor isn't cycling. Now, my A/C has never worked in the aspect of blowing cold air, however my compressor has always cut on when I either put the HVAC control on any of the A/C settings or on Defrost. I am getting neither, and I think since the compressor isn't engaging my stock e-fan isn't turning on either. Could this simply be a relay?
2) Where is somewhere in the engine bay I can get 12v power ONLY when the key is turned to "ON"? I need a power source for my e-fan conversion to the switch (fan has constant 12v from the battery to relay, the switch is the 12v when on only).
3) Can the little nub on the mech fan pulley be cut off? I'm talking about the little bit that sticks out past the actual mounting face. I think it is going to hit my e-fan.
4) How many amps is the stock cigarette lighter outlet? I have two 12v outlets I want to install in the ashtray and need a good 12v source to use.. and since I don't use the lighter and I think it only works when the key is on...
Thanks everyone!
Thread Starter
CF Veteran
Joined: Oct 2009
Posts: 2,867
Likes: 16
From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
Senior Member
Joined: Jul 2009
Posts: 739
Likes: 0
From: San Diego, CA
Year: 1996
Model: Cherokee
Engine: 4.0 HO
The compressor won't run when empty. Maybe your A/C didn't work because there's a slow leak that drained you to the point where there wasn't enough juice to cool you and now there's not enough to work the compressor. There's some sort of internal switch that won't allow it to. (I think the refrigerant is also the lubricant?) I would suggest that you evacuate your A/C completely and refill. I'm guessing it'll work after that. Check for leaks.
CF Veteran

Joined: Mar 2010
Posts: 1,441
Likes: 9
From: Georgia
Year: 99 94
Model: Cherokee (XJ)
Engine: I6
The compressor won't run when empty. Maybe your A/C didn't work because there's a slow leak that drained you to the point where there wasn't enough juice to cool you and now there's not enough to work the compressor. There's some sort of internal switch that won't allow it to. (I think the refrigerant is also the lubricant?) I would suggest that you evacuate your A/C completely and refill. I'm guessing it'll work after that. Check for leaks.
Senior Member
Joined: Jul 2009
Posts: 739
Likes: 0
From: San Diego, CA
Year: 1996
Model: Cherokee
Engine: 4.0 HO
Oh, ok. Anyway, the compressor won't run when there's no refrigerant for some safety reason. Mine wouldn't run, I loaded it up with refrigerant, BOOM! It worked great! For 2 weeks, until the refrigerant leaked out...
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Senior Member
Joined: Mar 2013
Posts: 691
Likes: 2
From: Texas
Year: 1993
Model: Cherokee
Engine: 4.0L
A convenient power-on only underhood source to switch a relay is the 12v side of the fuel pump ballast resistor. I've used this for so long on my '93 that I can't remember offhand what circuit is involved.
I guess it goes without saying that this is for a relay trigger only, not for a power source for any component.
On the '93, the fuse for the lighter is 15a in the #2 slot that also includes the radio and according to the book, a dome lamp. Not sure what dome lamp as
all interior lamps on my '93 are protected by 10a fuse #9.
I guess it goes without saying that this is for a relay trigger only, not for a power source for any component.
On the '93, the fuse for the lighter is 15a in the #2 slot that also includes the radio and according to the book, a dome lamp. Not sure what dome lamp as
all interior lamps on my '93 are protected by 10a fuse #9.
CF Veteran
Joined: Jan 2012
Posts: 3,170
Likes: 312
From: Australia
Year: 1997 (RHD)
Model: Cherokee (XJ)
Engine: 4.0 ltr
Mate, this is like "My car isn't running, I know the tank is empty, but can it be something else?"
May I suggest you refill it and check for leaks first.
CF Veteran
Joined: Jul 2013
Posts: 7,554
Likes: 17
From: Monett, MO.
Year: 1999
Model: Cherokee
Engine: 4.0
Really not a good idea to run the AC compressor without being filled plus adding the oil that is needed for the system to lubricate properly. If not working should have been disconnected.
Thread Starter
CF Veteran
Joined: Oct 2009
Posts: 2,867
Likes: 16
From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
The ballast resister for the fuel pump... where is this? And yes, for the relay trigger not the actual power source. Thats constant 12v from the battery.
CF Veteran
Joined: Jan 2012
Posts: 3,170
Likes: 312
From: Australia
Year: 1997 (RHD)
Model: Cherokee (XJ)
Engine: 4.0 ltr
Thanks. I just was curious because it had ran for 4 years since I bought it when it obviously had no output cooling wise. Wasn't sure if the relay could've simply gone. I didn't use it when it didn't work... I just noted it came on with defrost. I plan to get the leaks fixed and the system flushed and refilled.
The ballast resister for the fuel pump...
I don't have one, but I think you can find it on the inside of the driver side fender wall in the engine bay
...


