AC Compressor clutch not engaging, but R134a pressure OK - JeepForum.com
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post #1 of 22 Old 03-17-2012, 08:47 PM Thread Starter
polar8
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AC Compressor clutch not engaging, but R134a pressure OK

My 96 ZJ 4.0 Laredo does not have AC. The compressor clutch doesn't engage under any circumstance. I read that a possible reason might be that the refrigerant pressure was low, so I went out and bought one of those recharge kits from Autozone. With the engine running and the AC on and high, the pressure was right in the green where it should be.

What can I check next?

Thanks

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post #2 of 22 Old 03-17-2012, 09:00 PM
Oldfrog
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Jump the plug on the compressor switch with a hefty paper clip, getting it to engage the clutch, then look at the gauge. ( BTW those cheap gauges arent very accurate)

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post #3 of 22 Old 03-17-2012, 09:21 PM Thread Starter
polar8
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Quote:
Originally Posted by Oldfrog View Post
Jump the plug on the compressor switch with a hefty paper clip, getting it to engage the clutch, then look at the gauge. ( BTW those cheap gauges arent very accurate)
Where can I find the compressor switch?
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post #4 of 22 Old 03-17-2012, 09:24 PM
RedRocket1994
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There are two, but if you jump the wires at the switch atop the accumulator (big can next to coolant res), the clutch should cycle. If it does, then that switch is bad.

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post #5 of 22 Old 03-17-2012, 09:26 PM
garver21
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would like to know also im having the same issues
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post #6 of 22 Old 03-18-2012, 12:36 AM Thread Starter
polar8
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WOW! I was totally blown away by how easy and effective this repair was. I jumped the accumulator switch, and the compressor clutch activated. Then the reading on my refrigerant re-filler gauge was zero. I dumped the whole can in there and now my ac is ice cool. Removed the jumper and re-connected the cable and now the compressor clutch functions correctly and my AC is back. Thanks for the help!

However I still don't have heat- what could that be related to?

Here are some instructions on jumping the switch, I didn't know where to find it and this helped-

http://www.jeepforum.com/forum/f13/9...umper-1223272/
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post #7 of 22 Old 03-18-2012, 01:47 AM Thread Starter
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I decided it might be a good idea to flush the heater core in an attempt to get my hot air back. Flushed it using the garden hose method and the coolant that came out was definitely pretty rusty. Reconnected everything and now the air is warm. Not hot yet though, so I think I might go buy one of those heater core flush kits and try that method.
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post #8 of 22 Old 03-18-2012, 05:40 AM
merlot2twisty
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You might just want to do a complete cooling system flush.

Put the flush in the radiator and follow the instructions. Usually you drive the vehicle for several miles and then drain.

**VERY IMPORTANT**

Once you have removed all the flush and gunk, it's important that you refill the engine with distilled or dionized water (and antifreeze/coolant.) Water from your garden hose is useful for flushing or as an emergency or temporary fill, but there are far, far too many minerals in it that will wind up as crusty deposits in your engine, reducing its ability to transfer heat.

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post #9 of 22 Old 03-18-2012, 12:06 PM
garver21
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sry for the hijack

but if i jump the connector an my clutch engages an when i plug it back in nothing happens ,,, yes a/c is on max, yes it has freon in it ..... so do i need to empty the system to replace the switch on top of the accumlator???? sry for the bad grammer
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post #10 of 22 Old 03-18-2012, 01:52 PM
Oldfrog
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Quote:
Originally Posted by garver21 View Post
but if i jump the connector an my clutch engages an when i plug it back in nothing happens ,,, yes a/c is on max, yes it has freon in it ..... so do i need to empty the system to replace the switch on top of the accumlator???? sry for the bad grammer

Help me to follow you.

You jumped the connector.
The compressor clutch engaged.


This is where I lost you:

You "plug it back in"....and nothing happens.

Please explain.

2007 5.7 Hemi, Ltd. QD II -
1997 ZJ, 4,0 select trac, Up country, track lok.
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post #11 of 22 Old 03-18-2012, 01:53 PM
Oldfrog
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Quote:
Originally Posted by polar8 View Post
WOW! I was totally blown away by how easy and effective this repair was. I jumped the accumulator switch, and the compressor clutch activated. Then the reading on my refrigerant re-filler gauge was zero. I dumped the whole can in there and now my ac is ice cool. Removed the jumper and re-connected the cable and now the compressor clutch functions correctly and my AC is back. Thanks for the help!

However I still don't have heat- what could that be related to?

Here are some instructions on jumping the switch, I didn't know where to find it and this helped-

http://www.jeepforum.com/forum/f13/9...umper-1223272/
Glad you got it going !

If the flush doesnt help the heat, take a look at :
1. Blend door
2. Thermostat.

2007 5.7 Hemi, Ltd. QD II -
1997 ZJ, 4,0 select trac, Up country, track lok.
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post #12 of 22 Old 03-18-2012, 02:04 PM
Tangfan
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Need to do this to mine.
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post #13 of 22 Old 03-18-2012, 02:27 PM
Mickey_D
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Quote:
Originally Posted by Oldfrog View Post
Help me to follow you.

You jumped the connector.
The compressor clutch engaged.


This is where I lost you:

You "plug it back in"....and nothing happens.

Please explain.
Hope this helps.

He unplugged the connector. He jumpered the connector and the compressor fires up. He takes out the jumper and plugs it back in and the compressor no longer works.

This means the switch the connector plugs into is bad. He's asking if he needs to evacuate the system to replace the switch.

And the answer to his question is : Yes.

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post #14 of 22 Old 03-18-2012, 04:01 PM
cougar357
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If garver21 is replacing the low pressure cycling switch on the accumulator an
evacuation is not necessary. There is a schrader valve under the switch, just unscrew old one screw on new one. Either way you still dont have to evac to install a new switch.

Last edited by cougar357; 03-18-2012 at 04:37 PM. Reason: wrong person needing help
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post #15 of 22 Old 03-18-2012, 04:29 PM
samsonitesamson
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That's not what he was doing at all, he was getting in compressor to cycle so that he could charge the system to the point that the compressor would kick on by itself.

When thou walkest through the fire, thou shalt not be burned; neither shall the flame kindle upon thee ~ Isaiah 43:2 ~



Quote:
Originally Posted by Bnabb View Post
it bolted right up, except one bolt but i didn't need it anyway
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