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Unread 06-24-2013, 11:35 AM   #1
robertflake
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1998 ZJ 
 
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Another A/C Question

So the A/C in my ZJ is not working (constant warm air) and the compressor clutch contantly kicks on/off on/off.


I know that the level of refrigerant is correct (I took it to a friends shop and verified pressure), so is this a clutch problem? A compressor problem? I charged the system last summer and it did nothing; never have gotten cold air out of the vents...

I live in South Texas and it is super hot and I would love to have A/C this summer!

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Unread 06-24-2013, 11:36 AM   #2
zjosh93
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Bad clutch cycling switch.
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Unread 06-24-2013, 11:51 AM   #3
robertflake
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Quote:
Originally Posted by zjosh93 View Post
Bad clutch cycling switch.
is there any other names for that part? i cant find one of those anywhere lol
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Unread 06-24-2013, 12:01 PM   #4
zjosh93
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Look on RockAuto under Electrical-Switch & Relay, it's A/C Clutch Switch, two options. If you have a fully charged system and it's cycling it's a bad switch unless the orifice tube is so clogged up that the compressor is pulling the low side below the switch's trigger pressure. Worth a shot though, the switch is pretty cheap.
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Unread 06-24-2013, 12:04 PM   #5
Uniblurb
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Also called an AC pressure switch.

http://www.rockauto.com/dbphp/x,carc...ch_Switch.html

But before buying one put a jumper wire in the connector and see if the AC works while the clutch doesn't cycle as often.
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-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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Unread 06-24-2013, 12:15 PM   #6
robertflake
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Quote:
Originally Posted by Uniblurb View Post
Also called an AC pressure switch.

http://www.rockauto.com/dbphp/x,carc...ch_Switch.html

But before buying one put a jumper wire in the connector and see if the AC works while the clutch doesn't cycle as often.

where is this switch located?
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Unread 06-24-2013, 12:39 PM   #7
dellis
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Quote:
Originally Posted by robertflake View Post
I know that the level of refrigerant is correct (I took it to a friends shop and verified pressure)
Did your friend check both the high and low pressures with a manifold set?
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Unread 06-24-2013, 12:40 PM   #8
Uniblurb
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Quote:
Originally Posted by robertflake View Post
where is this switch located?
It should be right on top of the AC accumulator (also called the filter/drier) with the AC lines coming out of it. Just disconnect the connector from the switch, put a jumper wire in the plug between the 2 contacts, start your ZJ and turn on the AC.
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-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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Unread 06-24-2013, 12:57 PM   #9
robertflake
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I am not sure if he checked both high and low sides, he just said that the pressure is fine...

I found the switch and jumped it, the clutch stayed engaged and the smaller of the two ac lines immediately iced up, still no cold air in the cab though... did i just verify that the switch is bad? why am i not getting cold air?

when i took the jumper out, the ice melted and the line didn't feel cold (which i expected with the motor off), i then reconnected the switch, turned the a/c back on and the clutch was doing the same thing it was doing in the video, i felt the a/c line and it was definitely cold to the touch...
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Unread 06-24-2013, 12:58 PM   #10
dellis
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Maybe a blocked orifice ... a manifold gauge should be put on it to properly diagnose.
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Unread 06-24-2013, 01:06 PM   #11
a70eliminator
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Your not getting cold air because the evaporator is not filling with refrigerant, you low on charge. Evap not active, low pressure switch opening, suction line icing up, three texbook indications of low refrigerant charge. Was your ac working at the time your buddy said the pressures were good, if the compressor wasn't operating the pressure only tells you that there is SOME refrigerant in the system even just 1 ounce of freon 134a will make pressure.
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Unread 06-24-2013, 02:05 PM   #12
Uniblurb
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No, you didn't verify the switch was bad. Only verified it's some other problem, most likely low on charge as others said. You're going to have to get a set of manifold gauges to check it correctly and they have loaner sets at Autozone and/or Advance. You pay full price ($100-$150), can keep for 90 days, then return for a full refund. I got so tired of borrowing there's I bought a set off Amazon for about $70.

Once you have a set of manifold gauges your low/high specs should read something like in the below chart. This is for the 96 and someone else will need to verify the 98 5.9 is the same or similar. I read on another forum the specs for the 5.9 should be 20-40psi on the low side, 160-176psi on the high side, but these high end readings seem too low to me.

Have no idea why I can't upload a 83kb jpg image but it's not letting me. Grrr.. From the chart at 80 degrees the low side should be 32-41psi and the high side 200-260psi. Again, this is for the 96.
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-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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