ZJ Air conditioning help, please!

JeepeBago · 04-01-2009, 09:10 AM

Here is what I know:
The refridgerant level is in the "full" zone when tested with my gauge, but the compressor does not run.
When I connect a jumper at the connection where the schraeder valve is, the compressor runs, and cold air is present.
I do not have the digital climate zone.
At the front, there is a connector where an ambient temperature sensor would be connected. There is no sensor there. Could this be the problem, even though I don't have the digital set up?

Another thing I noticed is when I remove the under hood A/C relay, and plug it back in, the relay clicks and the compressor runs only for a second or so. Could it be the relay? Anything else I can check??

Thanks!
Adam

eBoyDog · 04-01-2009, 10:04 AM

The ambient temp sensor your mention, are you describing the one in front of the vehicle basicly behind the grill? If so I believe it has little to do with the AC operation rather it's used for engine computer and the fancy-dancy temp display on the overhead console.

Does the compressor run at certain intervals, say just for a few seconds, stops for minute or two and kicks in for a another second or two? That's an indication of a low charge. My best guess if it's not cycyling at all, you may have a bad low pressure switch on the accumilator.

Are sure there is a proper charge of freon in the system? did you check the pressure with the low pressure harness hot wired with the compresser running?

Also, are you using a high/low set of gauges or the one that comes on the recharge kits attached to a bottle? To get the best diagnostics, you need to know what the pressures are on both the high and low sides.

I have a copy of the 94 ZJ FSM with the AC/Heating information in PDF form, drop me a pm and I will email it to you, the 94 version covers the basics of even a 96 as I'm working on my 93 AC system so I looked it up.

As mentioned by another in my post about my AC issues, with the compresser running at 21 C (70 F) outside, you should have 26-35 psi on the low side & 180-240 psi on the high side.

Check out: http://www.flickr.com/photos/11927517@N04/3403841145/ This is the trouble shooting flowchart for the 93 AC system.

subliminal · 04-01-2009, 10:38 AM

Relay maybe?

EVIL ZJ · 04-01-2009, 10:40 AM

Just had the same prob. w/my 98 5.2...
After the install of the "Flex-a-lite" AC would only cycle for a few sec's then get hot (relay) & shut down...
Went down to "Car-Quest" & they had 3 in stock...
This tells me it is a very common prob.
Got 2 - Getting hot down here already & we WHEEL when it is 100+ ALL THE TIME...
Too hot not to have working AC...
It has worked fine since & only gets to around 200' w/new fan...
My 2-cents...M...VP. S.P.O.R.A.

Quote:

Originally Posted by JeepeBago

Here is what I know: when I remove the under hood A/C relay, and plug it back in, the relay clicks and the compressor runs only for a second or so. Could it be the relay? Anything else I can check??
Thanks!
Adam

comishcraig · 04-01-2009, 10:54 AM

Are you testing the refrigerant level while the compressor is running? If you're not, then it's likely that the level is actually low and the compressor is sensing that it's low and shuts itself off. When the compressor runs, the pressure drops because it's all flowing through the system. Keep the gauge on it and get teh compressor to run and then look at the level. I bet it's just low.

ianjadkins · 04-01-2009, 11:00 AM

So if I understand this right you are jumping the wires on the pressure sensor and when you do this the compressor kicks in. If this is correct wouldn't that tell you that the pressure sensor itself may be faulty? This sensor will stop the system from working and frying your compressor if the freon leaks out. Maybe it is faulty and thinks there is no freon in the system thus stopping it from working.

I don't think its just low because if it was it would cycle on and off every five seconds or so. You also said that when yu jumped it it blew cold air. When you jumped it did the compressor stay on for a long time, or did it cut in and out? If it cut in and out fast the freon is low, if it stayed on it will be full.

Just my opionon. Hope this helps.

Ian

JeepeBago · 04-01-2009, 03:38 PM

Thanks to all for your advice.
It's fixed! I didn't realize you are to check system pressure with the compressor running. It showed OK without the compressor running, but when I jumped the low pressure switch to engage the compressor, the gauge dropped to Low. I brought it up to the OK zone while the jumper wire was in place, then replaced the connector. The compressor continues to run now and only shut off for a second or two, then run again for about 7 seconds, cut off for two, run for seven seconds, etc. I am assuming this is normal operation? Now it blasts ice cold air. I am so excited! It's been several years since I've had a vehicle with working A/C!!

Only trouble now though is at idle, the belt squeals like a banshee. When I rev it up a bit, the squealing subsides. I checked the belt tension, and it didn't seem too loose to me.
I was worried that it was the compressor squealing, but I'm quite sure it's the belt.

Is there a place for oil in the compressor that I should check??

Thanks again,
Adam

rugermack · 04-01-2009, 03:56 PM

You add oil the same place you put in freon, it's called an "oil charge", there will be some freon in it also.

ianjadkins · 04-02-2009, 11:14 AM

Glad you got it going! I was in the same boat and re-charged mine as well. Lovin the A/C.

There are oil level checkers you can buy to test your system oil. I know that a company called redtek (they make an R12 refridgerant for refilling systems) redtek.com makes them. You simply push it on the low side port and the spray that comes out soaks into a foam pad and it changes color and soakes in different amounts to tell you how much oil is in your system. You need to know so you don't seize the compresspor since it will now cycle all the time even whey your A/C is not on.

As for the belt squeal, is it just when the A/C compressor kicks in? If it is I would take the belt off, and spin the A/C compressor by hand. Remember to not spin the pulley since the clutch will not be engauged, spin the part on the front of the compressor. Make sure it spins freeley with no snagging. That will tell you if the bearings in the compressor are shot.

Also check the clutch itself for wear. If the disks on the clutch are worn or glazed it will not fully grab and will make noise. The clutch can easily be replaced. Normally a clutch fails from another problem such as a seized compressor.

Hope this helps!

Ian