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Unread 07-23-2010, 01:52 AM   #1
DonMeister
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1998 XJ Cherokee 
 
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A/C loses power after 40 minutes

Hey all,

I did a search on the forums and couldn't find anything that matches my problem. I recently sold my YJ (R.I.P. buddy) and bought myself a nice '98 XJ. Great condition and everything runs great, EXCEPT

The Air Conditioning System
Now, bear in mind, I live here in Qatar (Middle-East) and now during the summer months the temperatures are constantly 35 - 50 degrees Celsius (112 degrees Fahrenheit). An A/C here is a must.

My A/C runs fine after starting the car, blows cold air like a champ. Sometimes, the air will come out of the defrost vents when I increase the throttle. I've read up about that and have come to the conclusion that one of the vacuum hoses is old and worn out. That's not my problem though, because in the end, cold air will still come out.

My issue is: After 30 - 40 minutes of driving, regardless of highway or city, the A/C will lose power and slowly increase in temperature. The compressor is still running and while it's not warm air coming out of the vents, it not as cold as it was when I started the car. I've recently recharged the unit with R-134a gas as stated on the manual, but that didn't seem to fix the problem. I personally think it might have something to do with the plumbing system. I have a suspicion that the A/C freezes as ice builds up in the system, because, after leaving the car parked somewhere with the engine OFF for an hour or two, the A/C will blow out sweet cold air again.

Has anyone been having the same problems as me? I will probably be taking it to an A/C shop to have a mechanic look at it, but it would be nice to have a starting point or some advice from the experts at Jeep Forum.

Any ideas or suggestions are greatly appreciated! Cheers beer

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Unread 07-25-2010, 12:32 AM   #2
DonMeister
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Unread 07-25-2010, 09:28 AM   #3
Crunch
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I have the same problem.... Sometimes it will last an hour or so, sometimes 15-20 minutes... Guy at a local shop told me my A/C clutch needs re-shimmed or replaced? Taking it to them this week.
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Unread 07-25-2010, 01:25 PM   #4
DonMeister
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Do tell what you figure out. I'm planning to take my XJ to the shop soon. Just waiting on some green in the wallet. My buddy said it might be the condenser, but he's not an expert, so it's prolly just dead-reckoning.
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Unread 07-25-2010, 01:57 PM   #5
Saudade
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Did you evacuate the system and then recharge it will a full charge? Or did you use one of those DIY cans with the crummy gage on it?

When you let it sit, is there a large puddle of water on the ground? of course it might evaporate quickly in the heat so you may not be able to tell.

When it's blowing cold at first, do you feel a strong blast of air out the vents? Once it starts warming up, is the blast just as strong albeit warmer or does it feel weaker?
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Unread 07-26-2010, 02:58 AM   #6
DonMeister
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Quote:
Originally Posted by Saudade View Post
Did you evacuate the system and then recharge it will a full charge? Or did you use one of those DIY cans with the crummy gage on it?

When you let it sit, is there a large puddle of water on the ground? of course it might evaporate quickly in the heat so you may not be able to tell.

When it's blowing cold at first, do you feel a strong blast of air out the vents? Once it starts warming up, is the blast just as strong albeit warmer or does it feel weaker?
No, I didn't evacuate the system before I refilled the gas. The shop used a crummy looking can with a crummy gauge on it.

Yes, when I let it sit, there is a lake of water on the ground, it comes out as if their were a water fall built into the undercarriage.

It takes a while to start blowing cold air, maybe around 10 minutes until it's noticeably cool. The electric blower is working alright though, besides the fact that the air comes out the defrost vents at higher speeds and ONLY in 5th gear. It does get a bit weaker but only after 5th gear at 120 km/h, for a while. Sounds like the compressor clutch might be slipping or the fan belt may be loose on the compressor. We drove 80 kilometers today in 4th gear at 110 km/h @ 2400 RPM without any issues to the A/C though.

Hope that helps diagnosing it further, thanks for the feedback, cheers!
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Unread 07-26-2010, 05:59 AM   #7
cruiser54
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Have the system evacuated and recharged properly. There could be moisture in the system.
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Unread 07-26-2010, 02:10 PM   #8
DonMeister
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I'll give that a try as well, but again, I need to save up some money first. Then again, in a few months, the weather will be cooler here again. Until then, I could just suck it up and drive around in 4th gear at max as that seems to keep the A/C nice and cool. Thanks for the suggestions guys!
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Unread 07-26-2010, 07:40 PM   #9
SubieHo
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check your AC relay -- may be sticky.
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Unread 07-26-2010, 08:34 PM   #10
83iS
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Another thing to look at is the Low pressure switch on the accumulator....mine would stick and the compressor would run non stop and freeze up the low side, and do the exact same thing you are describing, let it sit for about 15-20mins, fire it up and the air is perfectly cold, and for another 30-40 mins
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Unread 07-26-2010, 10:48 PM   #11
DonMeister
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Quote:
Originally Posted by SubieHo View Post
check your AC relay -- may be sticky.
SubieHo, I've never taken a look at the A/C system myself. Where can I find the relay and how do I check it? Do I just check it through with a volt meter?

Quote:
Originally Posted by 83iS View Post
Another thing to look at is the Low pressure switch on the accumulator....mine would stick and the compressor would run non stop and freeze up the low side, and do the exact same thing you are describing, let it sit for about 15-20mins, fire it up and the air is perfectly cold, and for another 30-40 mins
Wow great. How and where do I check the low pressure switch? Must I take it to an A/C shop for that?
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Unread 07-27-2010, 05:46 AM   #12
SubieHo
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Along the right fender and behind the battery, you'll find a relay box. Many of the relays are interchangeable. Swap another one for the AC relay to see if that fixes your problem.

As for the low/high pressure switch, jump the pigtail going into the switch and see if your compressor clutch engages.

If your compressor is running, then you should have cold air provided that you have a decent refrigerant charge.

If there's too much moisture in your system that is causing these symptoms, then you need to have the system evacuated and recharged.

Last edited by SubieHo; 07-27-2010 at 08:04 PM.. Reason: typo
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Unread 07-27-2010, 06:10 AM   #13
DonMeister
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Got it, will definitely have a look at these things in time. Thanks for the help SubieHo !
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Unread 08-01-2010, 09:20 AM   #14
Weebur
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It sounds like your evaporator is freezing up. Chrysler has issued FSB indicating that they have recalibrated the low pressure switches that deals with this issue. There are different part numbers for the '97 and '98, your dealer should be aware of this.
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Unread 09-06-2010, 04:09 AM   #15
DonMeister
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Right, so I did change the low/high pressure switch as mentioned by SubieHo... it still loses power after about an hour and a half of running. And still, after turning the car off after that period of time, I'll let it sit for a bit and come back to find a newly formed lake under the front passenger side. Garage says they'll have to keep the car for a few days to diagnose it properly.

Weebur, do you have a link for that Chrysler post?

40 degrees Celsius and 50% humidity today... ahhh
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