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NCXJMAN
May 31st, 2006, 16:12
Well i went to take a date out the other night, and she didnt want me driving with the windows open, so i turned on the ac. well it worked great for about 20 min then it blew warm. it now does this all the time, starts really cold then gets warm. I recharged the refrigerant but it didnt seem to help. its a 2000 model any help before the next date would be great!

scoobyxj
May 31st, 2006, 16:27
Take it to a shop that does A/C work. You cant just go adding refrigerant without having gages on the system to tell you if you have the right amount in it. You probibly have two much in it, and it is popping the high pressure cut out.

sandmcrew2
May 31st, 2006, 16:33
This happened on mine, took forever to find good info, but the problem was the AC Clutch "air gap". What happens is the ac clutch wears over time from it engaging/ disengaging every few seconds, and the gap between the clutch and the pulley gets bigger and bigger over time. Since these things are operated via electro-magnets, when the gap gets bigger, it makes it harder for the magnet to pull in the clutch to engage it. The reason it will work for a little while and then stop is because when underhood temps rise, the resistance in the clutch coil rises and thus the magnetec force gets weaker. To fix this all you need to to is take off the serpentine belt, unbolt the 4 bolts on top of the compressor that hold it down (leave the lines connected) and pull the compressor up so you can access the main bolt in the center of the clutch. Loosen the bolt (I used an impact, though not neccissary, its only tightened to like 22 lb/pounds), then use two screw drivers to gently pry the front clutch face off. when that is off you will see 2 little washers on the shaft, take one of those washers out to bring the clutch closer to the pulley, assembly is the reverse of removal, and voala!! Hopefully this fixes your problem. BTW mine is a 98, and I just bought it, got a good deal on it cause the AC didnt work right :).
Here is a link the the manual covering this procedure, our 97+ XJ's have the sanden SD7H15 compressor.

http://www.sanden.com/support/pdf/sd7servicemanual.pdf

Good luck
-Jerry

anony91xj
May 31st, 2006, 16:50
Take it to a shop that does A/C work. You cant just go adding refrigerant without having gages on the system to tell you if you have the right amount in it. You probibly have two much in it, and it is popping the high pressure cut out.
Yep, you probably added too much refrigerant at this point. Have a shop evacuate the system and refill it, then go from there...try the compressor clutch solution above.

Ivan
May 31st, 2006, 17:17
Beyond the AC clutch that will fail over time as mentioned above, you should also look into your low pressure switch. If it's bad, it will cause the evaporator to freeze over. This creates ice, which blocks the air flow through the evaporator, which is why you feel the warm air after about 15 minutes. Once the ice melts off, it'll work fine until it freezes over again and repeats the cycle.

Search low pressure switc... there's lots of info on that.

BTW.... I replaced the low pressure valve on my '98 and it ran fine for about 5 months, then I had to replace the AC clutch. The AC has been fine now for about 2 years....

UNCC_99XJ
May 31st, 2006, 20:28
You mention you have an 01. The last generation XJ's are well known for leaking evaporators. They all do it at some point in time. Perhaps yours is leaking and your low-pressure cut off switch has kicked in?

RyanM
May 31st, 2006, 22:47
Take it to a shop that does A/C work. You cant just go adding refrigerant without having gages on the system to tell you if you have the right amount in it. You probibly have two much in it, and it is popping the high pressure cut out.
yep. look at the clutch on the ac compressor, is it turning on and off rapidly?

Rambo
June 20th, 2006, 10:41
This happened on mine, took forever to find good info, but the problem was the AC Clutch "air gap". What happens is the ac clutch wears over time from it engaging/ disengaging every few seconds, and the gap between the clutch and the pulley gets bigger and bigger over time. Since these things are operated via electro-magnets, when the gap gets bigger, it makes it harder for the magnet to pull in the clutch to engage it. The reason it will work for a little while and then stop is because when underhood temps rise, the resistance in the clutch coil rises and thus the magnetec force gets weaker. To fix this all you need to to is take off the serpentine belt, unbolt the 4 bolts on top of the compressor that hold it down (leave the lines connected) and pull the compressor up so you can access the main bolt in the center of the clutch. Loosen the bolt (I used an impact, though not neccissary, its only tightened to like 22 lb/pounds), then use two screw drivers to gently pry the front clutch face off. when that is off you will see 2 little washers on the shaft, take one of those washers out to bring the clutch closer to the pulley, assembly is the reverse of removal, and voala!! Hopefully this fixes your problem. BTW mine is a 98, and I just bought it, got a good deal on it cause the AC didnt work right :).
Here is a link the the manual covering this procedure, our 97+ XJ's have the sanden SD7H15 compressor.

http://www.sanden.com/support/pdf/sd7servicemanual.pdf

Good luck
-Jerry


Jerry , you mention to loosen the main big bolt? did you take it all the way off? or just loosen?
thanks

buffalomatt350
June 20th, 2006, 17:36
I agree with take it to a shop. There are so many variables at this point and without proper equipment like a set of gauges and the machine to evacuate/recharge it's too easy to misdiagnose the problem. There's a good chance the system is overcharged, or a sensor is bad, or your evaporator is flooding or icing for some other reason, depending on how exactly the system is designed. You might luck out with parts guessing, but in the end it'll probably be cheaper, and alot easier on you to have it done at a shop with the equipment. Not to knock your skills or anything, I'm just suggesting.

RichP
June 20th, 2006, 20:39
97+ XJ's have cheap evaporators, they leak, it's a common problem, just do a search on here for 'evaporator' or 'removing dashboard', it's an 8 hour job. To verify it go pickup a couple of cans of R134 with dye in them, add one can till the compressor starts cycling and drive around, when the compressor stops cycling normally add the other can and do the same thing. Then take a black light and look for the yellow stain, you will find it where the rubber hose comes thru the firewall on the passenger side right above the frame rail, eventually the condensation will carry the dye out. It is a bitch of a repair, the evap is inside the heater box behind the dashboard and it all has to come out to get to it, thats the reason the dealers charge anywhere from $900-$1200 for the repair, it's all labor and a $200 evaporator. Mine goes in in 21 days, soon as my daughter is down in philly going to temple and I inherit her TJ...

According to the FSM [factory service manual] the compressor should only cycle 5 times in one minute on HIGH and COLD setting, any more than 5 times the freon is low..

reliablestv
June 20th, 2006, 20:53
a simple thing to check is pinch off your heater hoses to block the flow make sure your heater isnt warming you ac

lilredwagn
June 20th, 2006, 20:55
she didnt want me driving with the windows open
You can do anything you want with the A/C system, but you'll only be alleviating the symptoms, not solving the problem :D