aa7kn

My 1991 Cherokee is allot of fun. I love my jeep. I have noticed the aux fan cycling on and off allot with the A/C. is this normal for the 91 XJ ? it is normally set to normal and cool and it is always turning on and off....even the compressor I do believe. any ideas ?

The_ocho

compressors cycle all the time in any vehicle. its just more noticeable here because the fan is so noticeable.

duckcreek

when the a/c clutch is engauged the ele fan will be on to keep the a/c head pressure down

CCKen

If the fan cycles too much (subjective) it could be that your AC refrigerant charge is low. Check the Evaporator inlet pressure at the low pressure charge port with a cheapo gauge from Adavance or O'reilly auto parts. At 71* F outside air temp, it should be between 26 and 35 psi, and at 110* F OAT it should read between 50 and 60 psi.

aa7kn

thanks guys for the info. also do I need the aux fan ? it is no where near the compressor so I think it is just to aid in cooling. can I discon it so I won't have to listen to it all the time ? also, I have noticed that when the fan is hooked up, it sure draws alot of current. my volt meter gets all the way down to the red sometimes. when I turn off the A/C, it stays up to almost the 14 on the meter. 13.8 at the battery with my multimeter. it is either I am not getting any voltage regulation, or the fax is bad and it is drawing to much current....any thoughts ?

Johnthepanpire

Yikes! Volt drop like that you might have a busted alternator. When was it last changed?

freegdr

mine does same thing been thru new alt blower motor suspect ac clutch aint changeing it untill ac needs work...just saying

cruiser54

Actually, all the voltage deop readings on the gauge are pretty normal. A good ground refreshing with upgraded cables will reduce it alot.

And yes you need the electric fan in order for your aC to work well.

aa7kn

Thanks again, I sure appreciate the comments for sure. Yes I have a new alt, didn't help. I was told the regulation is done in the PCM, so I changed that also, no help...the only thing that keeps the voltage up when the A/C is on is to unplug the Aux. Fan. the Aux. fan was not there in earlier than 1991 models and everything was ok, don't know why they added it in 1991, but the car runs and cools well without it. so I hope some one has a answer to my problem. I have NOT tried another Aux. fan, that very well might be the problem.

jakbob

any cherokee with a/c has an auxillary electric fan. case in point, mine. 1987 with aux cooling.

cruiser54

True story.

Johnthepanpire

^X2
'90 with a fan

aa7kn

ok ok, I stand corrected, I thought I read that on after 1991 the Aux fan came into play....thanks guys for the info.

salad

Since noone specifically mentioned this, the aux fan actually does pull air through the condensor coil for the A/C. There's a smaller radiator sitting in front of the main engine rad where the electric fan is. You can see it if you pop off the front grille

XJPhoenix

Another thing that pops into mind... Maybe the OP's Aux fan is on it's way out. It's loud and draws lots of power...

Used ones from the scrapyard aren't too expensive. Plus, you could upgrade to one from a later (94-up) XJ with the swept blades. They're supposed to pull more air, and are quieter.

HTH!