A/C not working - no cold air

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Adam Roby

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Hi Guys,

Is there a "how-to" on A/C troubleshooting? I am looking through the list but not finding what I am looking for. I am seeing some threads about checking clutches, compressors, condensers... all a foreign language to me, I've never even looked at the A/C components before. I obviously need to do some research on how they work to know what to look for, but I was hoping there would be a check-first type of guide, maybe even with pictures to help identify all these different components.

Background: First days of spring here in Montreal. I finally needed a bit of air being stuck in traffic yesterday afternoon. Turn on the A/C... normally gets really cold in no time... never got cold. In retrospect, this winter I had a lot of trouble with fogging up windows, never occurred to me that the defrost might not be working because the AC was out.

I guess step 1 would be to see if there is a blown fuse or relay?
Is there stuff I can look at myself, like the Freon level or is that a professional only type check?

Thanks for any assistance you can give.
 

LibertyTC

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To learn more read 2006 factory service manual heating & cooling section: http://www.colorado4wheel.com/manuals/Jeep/KJ/2006-KJ-SM.pdf
Even in the winter set to defrost mode, the compressor should engage the clutch.
With dash dials to cool and other to re-circulation mode does the compressor clutch engage or spin?
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Adam Roby

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Thanks for the reply, I will check the link.
Just looked under the hood, the clutch does not engage (it does not spin).
 

HoosierJeeper

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It's low on refridgerant and that's why the compressor won't run...there's a leak somewhere. Honestly there's not really an easy DIY way work on AC...unless you do it for a living it's not something to play with, easy to mess up.
 

Adam Roby

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If there is a leak, is it generally an expensive repair? I mean, are we talking a couple hundred or much much more?
 

HoosierJeeper

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Depends, it could be some really easy like a hole in the condenser or in the compressor. Worst case it's the evaptorator core which is behind the dash, but KJs aren't known for that.
 

LibertyTC

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The next step is going to be finding an auto AC shop that you feel comfortable with.
I like to know in advance their hourly shop rate, and ensure they are certified.
I also want to mention that having a fine metal screen behind the grille, can protect the condenser from rock damage/leaks.
Hopefully within 1 hour labor, the shop should be able to determine the leak location/s, and give you a quote for the repairs with required parts.
Compressor, condenser & lines are the normal culprits.
 
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mrhemi

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KJ's are known for the pressure switch on the accumulator failing, witch seems like low refrigerant. Jumper the switch, the compressor will run, if it blows cold air it is likely the switch, which you can replace yourself without evacuating the system. BUT DON'T LET IT RUN TO LONG JUMPERED. If it is actually low on Freon, it can damage the compressor.
 

LibertyTC

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I personally would not jumper the pressure switch as it could be very low on refrigerant as mentioned, potentially damaging compressor.
To know if it is low on refrigerant the shop will firstly attach pressure gauges to the schrader valves & know what the readings are.
 

tjkj2002

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Somewhere between being sane and insane!
To know if it is low on refrigerant the shop will firstly attach pressure gauges to the schrader valves & know what the readings are.

if the compressor clutch will not engage both high and low sides will read at about ambient temp.Plus pressure readings can not tell you if the system is low or fully charged.

The one and only way to tell if the system is low or not is to evac the system and weigh what came out and should be the 1st thing any shop does.
 

Whelan

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The way we diagnosed was to ensure the clutch was engaging by the steps posted above. Once that was confirmed we bought a recharge kit with dye in it. This primes the system then allows us to use the goggles/light to find where a possible leak was. Turns out it was a tiny pinhole in the condenser, installed a new one and did a second recharge on the system. Thankfully a buddy have the vacuum/gauge set for this we were able to fill/purge the system pretty easily and everything was back to normal. I swear her system blows colder air than my car which is 8 years newer.
 

JeepJeepster

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Check pressures to make sure thats why its not kicking on, evacuate system, add dye/refrigerant(no leak stop!) by weight/pressures, buy a UV light/glasses, find the leak, fix leak, evacuate again and add refrigerant by weight/pressures in the FSM.

Cost could be out of control depending on if you do the work yourself/have a shop do it/whats wrong.

Working on the A/C in these jeeps is super easy IMHO...
 

Adam Roby

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Thanks for all the comments, much appreciated.

I don't know any A/C shops personally. Its winter most of the time here so not many of us have had to deal with it. I did find a shop that seems to specialize in A/C, and they have a promotional deal for $49.99 they said they do a full inspection and give you an estimate. I guess worse case I am out $50 if they can't diagnose or give me a crazy estimate. Best case its an easy fix or they tell me what needs fixing and I can make an educated guess if I can handle it or not. I'll try to get an appointment in the next couple weeks and report back with the estimate.
 

jeepop

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I figured it out, you can too. Mine leaked right in the middle of the compressor body.

Thus, I knew it had no gas in it. Different story if yours is loaded with gas and not leaking.


I got a kit that came with all new o rings, compressor, dryer. Rock Auto sells them.

Removed compressor, filled new with oil, bolted it on. Pulled lines, blew out with compressed air, replaced o rings, reattached.

Got the loaner tools from autozone, watched a few videos and read on line, pulled vacuum on it. then put the amount of gas it says to install on the front of the engine compartment.

Returned parts, enjoyed cold air.
 

Adam Roby

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Well, my KJ ownership time has finally elapsed.
It was an interesting and expensive 2 1/2 years.

I never got around to fixing the AC - too many other issues to fix and now the TC is grinding. Fed up... not sure I will be looking at another Jeep product for some time.

Upgrading my ride to an F150, it should suit my current needs better than the Jeep will.

Farewell and best of luck to you all.
- Adam
 

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