Hey guys, I'm new here. Just picked up a new to me 2002 KJ Sport 4x4, 3.7 NV3550. It has 82k miles on it. Never thought to check during the test drive, but when I went to use the A/C today it didn't work. Drove around for about 10-15 minutes and it never got cold or even cool. Didn't think to stop and listen for the compressor, I'll have to check that out later. My question is, has anybody ever done an R-134 recharge by using one of those recharge kits they sell at the parts stores? I was considering that. They seem pretty cheap and easy. Also, is there a relay for the A/C compressor that is commonly known for going bad on KJ's? Maybe I'll look at that, too.

Well, any suggestions you guys could give to get my A/C back in working order would be greatly appreciated. It's HOT here!

Well if the A/C isn't working then the R134a leaked out(or most of it) which means you may need new o-rings or seals.The compressor clutch seal is a big one for going bad and leaking.I would take it someplace to have a leak test done first or you will be wasting your money just adding R134a then having it leaking all out again.Take it back to the place you bought it from and see if they will fix it,they should if you just bought it(like within a week).That all applies if the comprssor is kicking in,if the compressor is not kicking in it could be a short,bad relay,or the high pressure(or low pressure) switch went out.

OK, I checked the pressure in the system (low pressure side) and it was almost 100 psi. Pretty high...obviously it's charged up. I did notice that the compressor is not clicking on at all. I'll change the relay and check the fuse. Assuming it won't be that easy, how hard are compressors to change? Can it be done by the shadetree mechanic?

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2002 KJ Sport 4x4, 3.7L NV3550
Cardomain Page
http://www.cnyjeep.org

If you don't have the proper equipment, seek out help. It's money well-spent if you're somewhere HOT.

JP

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2003 KJ Limited - Stone White 4x4

Bone Stock, but the
stock stereo must go!

OK - checked the fuse and replaced the relay - compressor still not kicking on with A/C. At all. Checked eBay and found a good rebuilt compressor for around $100, dealer quoted me $165 for evacuation and refill + R&R of the compressor with my part. $265 total isn't bad for the job, right? Hopefully that works for me!!

I'll keep you all posted. Thanks.

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2002 KJ Sport 4x4, 3.7L NV3550
Cardomain Page
http://www.cnyjeep.org

Before you spend all that money you may want to check the high/low pressure switches,if one of those goes bad your A/C won't turn on and those switches are alot cheaper than $265(maybe $20-$40 apiece).Or it could also be the HVAC unit in the center console to.

Where might I find the high/low pressure switches? Somewhere in-line with the hoses? What kind of job are those to do? How about this - is there a way to check the compressor by bypassing the rest of the Jeep altogether? Like somehow apply 12v to it directly and see if it kicks on? The rest of the HVAC functions work normally so I'm not too sure that it's the controls themselves...

Thanks alot for the suggestion!

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2002 KJ Sport 4x4, 3.7L NV3550
Cardomain Page
http://www.cnyjeep.org

I'll take pics of the switches for you and post later(got to go to the dentist in a few ),they are easy to change.

Cool thanks. I'll be at work until 11pm tonight anyway - no rush.

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2002 KJ Sport 4x4, 3.7L NV3550
Cardomain Page
http://www.cnyjeep.org

For starters this wiring color coding is for only '02-'03 KJ's with the 3.7.

Item #1 is the AC pressure transducer(AKA-high pressure switch,located on top of the AC compressor)

Black/Light Blue=ground

Dark Blue=AC pressure signal(out going)

Violet/White=5v supply

Item #2 is the compressor clutch connector

Dark Blue=12v power

Black/Gray=ground

The next pic is the low pressure switch(located on the reciever/dryer just to the left and below the coolant tank)

Dark Blue/Orange=power

Black/Orange=ground

Hope these help out some.Oh by the way when replacing these switches you do not have to worry about looing the R134A,the switches screw onto a valve core like your tires have so no R134A is lost.

Actually tjkj2002 I think that black and orange is a path for voltage to compressor clutch coil. Before you buy a low pressure switch,you can run a jumper across the low pressure switch connector,if the clutch on the compressor kicks on,and you know for sure that you have enough 134a in the system (hence cold air from vents)then most likely you have a bad switch.If the clutch does'nt engage,then check for voltage and ground at clutch coil .If you have both power and ground at clutch coil,the clutch coil is bad or the airgap is too large for the electromagnetic coil to engage it.

Ron

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Ron
03 Red Libberty Sport
3.7 V6 Auto 4x4
Lifted
Cooper Discover ATRs 265/75/16
American Racing 16x8 Polished Baja Wheels
Moog Lower Ball Joints
Member#051397 L.O.S.T. Midwest

Nope,for the '02 models the Black/Orange wire is the ground for the low pressure switch and the Dark Blue/Orange is from the A/C switch sense in the PCM.The Dark Blue/Black wire on the compressor is the supplied voltage to the compressor clutch via the A/C compressor clutch relay,the Black/Gray is the ground.I just double checked on my wiring diagrams.You are right about jumping it though to see if the compressor kicks in.

100 psi on the high side and you are still low. You are low on 134a and have a leak-I bet your compressor is fine. You need to pull the plug on the low pressure sensor on the accumulator and jump it. That will get the compressor running and you can measure the pressure. You should have around 200psi with the system running, or better yet measure on the low side for about 30 psi depending on the ambient temp.

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Right from the '02 service manual---

70 degrees(outside temp)-low side+20-30psi////high side=150-200psi

80 degrees-low side=25-35psi////high side=200-300psi

90 degrees-low side=30-40psi////high side=250-350psi

At a 110 degrees(outside temp) it should not exceed---low side=50psi max////high side=430psi max

thanx for the pressure values tk, I knew I was close.

Before you buy the compressor, pull the grey plug with #1 pointing to it in the second pic. Stick a wire between the two holes. Your compressor should kick on. If it does, you're low and dont need the compressor.

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All I can say is WOW...a guy really can't ask for better help. Thanks a million you guys.

Now I could have swore I checked pressure on the LOW side with my recharge kit - low side pressure with the A/C turned on (the compressor was obviously not coming on) was just under 100 psi. Maybe I checked the wrong port. I will jump the low pressure switch today and see if the compressor kicks on. It's been about 85 degrees here lately, so use those values.

TJKJ2002, Thank you for the pictures, they help a ton.

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2002 KJ Sport 4x4, 3.7L NV3550
Cardomain Page
http://www.cnyjeep.org

OK, went out to check the pressure switches as directed...found the low pressure switch (this one)


just sitting there, not plugged in! Snapped it on and I had ice cold air instantly, compressor came right on! I hooked up the gauge to the low pressure line and it was steady right under 30 psi (now that the compressor is running), at 76 degress ambient temp outside. Perfect! I'll keep an eye on it anyway.

TJKJ2002 and DAVEKJ02, God only knows how much money you guys just saved me in diagnostic costs and replacing parts that work fine - I have zero experience with HVAC systems and I never would have thought to check that the low pressure switch was on, off or faulty. I owe yas a cool one if you ever visit central New York state. I've owned Jeeps for years and belong to numerous forums, and this is by far the best advice I have ever received. Thanks a ton guys. Problem solved, case closed.

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2002 KJ Sport 4x4, 3.7L NV3550
Cardomain Page
http://www.cnyjeep.org

I just had mine at the dealer yesterday to fix the AC (I took it straight there without looking into of it myself, because it is still under warranty). Anyway they had it all day, said they recharged it and also found that the fuse was blown. So when I go to pick it up, he says "can you bring it back next week, after we replaced the fuse and tested it, it just blew the fuse again and again." So I am scheduled to take it back on Monday, but I have an hour drive each way to work and back everyday and the temp in starting to hit 90. It sucks. I think I might try to look at it myself over the weekend because I am thinking there has to be a failed component that is shorting itself out. TJKJ2002 and DAVEKJ02 do you know of any components that it is common for them to fail and short out? Any info you might have that could help me and/or the dealer figure it out would be awesome. Thanks.

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My best guess on that one is to check the A/C relay,find another relay like it(like for the horn or something that won't effect the vehicle starting and running) and swap it with the A/C one.If that doesn't do it start checking all the electrical connections for corrosion and grounds for corrosion.If all is well with that stuff let the dealer(and warrenty) take care of it,it may have a bad compressor clutch.

Your welcome.Just didn't see the need for you to spend alot of money when some simple easy checks could take care of it,glad it was a simple thing and is now working.Just remember the the word K.I.S.S.---stands for Keep It Simple Stupid,works alot in most cases,check fuses,electrical connections,relays,and grounds first.Then when all else fails then take it in to have looked at.