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Discussion Starter · #1 ·
Trying to get some cool air in my 99 4.0L wrangler. The compressor will kick on for a second, then off for 10. I thought it was just low on R134, then i hooked the gauge up. Is this normal? How can i get cold air back?

BTW, when it gets to the red and drops, that's when the compressor kicks on.


 

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This isn't an old R12 system, you cannot judge the amount of refrigerant in the system based on pressures. You have a leak somewhere, and don't have enough of a charge left in the system for it to work.

You can get your cold air back by taking it to someone who has the equipment necessary to properly service the a/c.
 

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It's kicking off because of high pressure, You need to evacuate the system and charge it with the correct WEIGHT of R134A not by pressure alone.

Then see if the problem persists. Also make sure your fans are working correctly, if they don't come on or your fan clutch is toast then you'll get high pressure as well.

A compressor clutch failure will not cause a quick cycle like this. The pressure guage is evidence that it's a high pressure issue.
 

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Is your condenser fan coming on? If not the system will build pressures rapidly and then cycle itself off. One way to tell if it is your condenser fan is to drive about 50 - 60 mph steadily on the highway, especially with the sun down; if your a/c blows cold then but constantly cycles at idle you likely have a bad fan.
 

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you need a manifold to read BOTH high and low side pressures. without this it's impossible to accurately diagnose an AC system.
 

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Too hard to diagnose with a $20 PepBoys "Fill Yer Own AC Gauge Thingy." I would start by taking it somewhere that can properly diagnose it.... most likely just needs evacuated and refilled to the proper weight.
 

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i thought the wranglers only had one thermostatic fan.
The 4.0L Wrangler has a mechanical fan, not an electric one. If the fan were to blame, he'd have already started a different thread about his engine overheating. ;)
 

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Had the same problem in my GTI. Turned out that the AC clutch was bad.
This. The clutch is a wear item and when the gap gets too large, it never engages.

On my Saab, you can remove the AC clutch and pull out a few shims (washers) and then the clutch can engage.
 

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you need a manifold to read BOTH high and low side pressures. without this it's impossible to accurately diagnose an AC system.
Yes.

Having a gauge on both sides will allow him to see what's going on and how the hi and low side are behaving.

This is a simple example of what you can diagnose if you have both readings

 

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i'll try and get a hold of one of these. autozone USED to rent them, doubtful they still do though
:thumbup: you may have a restriction in the system, and the only way to find out is with a manifold....once we have high/low readings, we can better diagnose the problem.
 

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AC guy here....you have too much of a charge in your system. the compressor kicks in and starts to build up the pressure. the system is then shutting off on a high pressure limit switch. the system needs to be evacuated and charged correctly.
 

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Discussion Starter · #19 ·
It's pretty obvious the clutch is engaging.... that isn't the problem.
it is engaging

:thumbup: you may have a restriction in the system, and the only way to find out is with a manifold....once we have high/low readings, we can better diagnose the problem.
will do

AC guy here....you have too much of a charge in your system. the compressor kicks in and starts to build up the pressure. the system is then shutting off on a high pressure limit switch. the system needs to be evacuated and charged correctly.
the pressure drops when the compressor clutch engages
 

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