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Unread 09-29-2009, 06:34 AM   #1
twmart
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1999 WJ A/C Not Working?????

I have a 1999 WJ with the 4.7 engine. My A/C does not work the compressor is not engaging. Here is what I have found so far
The fuse and relay are good.
I can hear the fuse click when the A/C is turned on.
I have done all of the testing in the FSM pages and that is all fine also.
I hooked up the A/C gauges tonight and the static pressure is 78-80psi at (60deg outside)
I unconnected the low pressure switch and when bypassed the compressor starts.
The pressure on the low side with the switch bypassed was 28-29psi.

So my question is is my freon low or does this sound like the low pressure switch in bad? Or maybe both?
What sound the static pressure in the system be at?

Thanks
Tom

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Unread 09-29-2009, 06:44 AM   #2
Airborne Lee
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start with the switches! jeepair.com has parts. (Check the wiring first. could it be loose at the connector?)
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Unread 09-29-2009, 06:49 AM   #3
twmart
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Oh the switch I bypassed was the one on the top of the Accumulator just behind the battery this is the low pressure switch right?
The other switch is on the small line on the frame rail by the radiator.

Thanks
Tom
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Last edited by twmart; 09-29-2009 at 09:54 AM..
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Unread 09-29-2009, 06:56 AM   #4
Airborne Lee
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Yes those are the switches. If the wires into the switches are ok (not loose) then you might try to replace the switches. I have replaced the high pressure switch at the condenser but not the low pressure at the accumulator. There are no issues with the high pressure switch just make sure you have the replacement o ring gasket. (Should come with the switch.) But I think the low pressure switch is likely where your issue is.

Can someone confirm that this switch can be pulled from the accumulator without dumping the R134a?
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Unread 09-29-2009, 08:33 AM   #5
twmart
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Quote:
Originally Posted by Airborne Lee View Post
Yes those are the switches. If the wires into the switches are ok (not loose) then you might try to replace the switches. I have replaced the high pressure switch at the condenser but not the low pressure at the accumulator. There are no issues with the high pressure switch just make sure you have the replacement o ring gasket. (Should come with the switch.) But I think the low pressure switch is likely where your issue is.

Can someone confirm that this switch can be pulled from the accumulator without dumping the R134a?
Thank you I was just going to ask the same question about the R134a coming out when I change the switch.
Can I use a switch from Advance or Checkers etc or is this like the engine sensors and I should get a Mopar switch?
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Unread 09-29-2009, 09:56 AM   #6
Airborne Lee
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I doubt that you have to or should to use Mopar for this unless the price is close to the same and they have it.

The description from the FSM says specifically this can be removed without discharging the refridgerant. So your good. But lilke I said before, make sure you have a replacement o ring with it.
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Unread 10-01-2009, 08:35 AM   #7
twmart
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Thanks for the help I replaced the switch and everything is working again. The switch did not come with the O-ring so I bought a small o-ring kit.
My gauge reads 40 low and 325-350 high
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