Test AC Clutch / Compressor

[B1Toad]

So the 70 PSI is normal when not running?

I will start tracking it down maybe this evening. I tried getting to the clutch plug without success.

Yes, when not running the charge equalizes on both sides. Once running the suction side will drop and the pressure side will rise.
You can quickly test your pressure switches with an ohm meter, they should both be closed with zero or near zero resistance between the terminals.

 

[mjonesjr84]

Yes, when not running the charge equalizes on both sides. Once running the suction side will drop and the pressure side will rise.
You can quickly test your pressure switches with an ohm meter, they should both be closed with zero or near zero resistance between the terminals.

The low pressure switch (on the dryer) is closed and has 0.2 Ohms. The high pressure switch is closed and showed 0 Ohms.

 

[B1Toad]

Reasonably sure we can eliminate the switch since when you jumped the connector you still didn't get clutch operation.

 

[mjonesjr84]

Any recommendations on a replacement clutch?

 

[Cooper Smith]

Check the pressures in the system, if there is no refrigerant then clutch won’t turn on. That is where to start.

That's why you jump the pressure switches to trick it into engaging.

 

[Cooper Smith]

Any recommendations on a replacement clutch?

Never done a compressor job on a TJ, but Rockauto has a UAC clutch assembly, and a Mopar clutch coil. The P/N is 5016376AA for the clutch assembly. What I found that was OEM and in stock was hundreds, and hundreds of dollars. Rockauto doesn't have many AC Clutch Mopar options, so if you care about that, may make it a little harder. I used Four Seasons once and wasn't disappointed.

 

[mjonesjr84]

Never done a compressor job on a TJ, but Rockauto has a UAC clutch assembly, and a Mopar clutch coil. The P/N is 5016376AA for the clutch assembly. What I found that was OEM and in stock was hundreds, and hundreds of dollars. Rockauto doesn't have many AC Clutch Mopar options, so if you care about that, may make it a little harder. I used Four Seasons once and wasn't disappointed.

Was the change very hard? Assuming you removed the fan and shroud to get to the clutch?

 

[Cooper Smith]

Was the change very hard? Assuming you removed the fan and shroud to get to the clutch?

I've never worked on A/C on a TJ. My A/C worked when I bought it and somehow still works. I just looked up part numbers for you is all.

 

[B1Toad]

The answers to all your questions are in the 2000 service manual below, including a step by step on replacing the clutch. I haven't changed a compressor clutch on a TJ either but I put one on my Ford and it was a piece of cake.

edit: the pdf won't load but go here: https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/ and the 2000 manual is down in the second to the last row,

 

[NskLJ]

That's why you jump the pressure switches to trick it into engaging.

I’m well aware how to diagnose a A/C system. Once you jump the switch and the clutch engages then you need to check pressures. I am trying to give him a logical path to diagnose the A/C system. If he puts a clutch on it and the compressor is bad then you just wasted the Money on the clutch as most compressors come with a clutch already installed.

 

[Cooper Smith]

I’m well aware how to diagnose a A/C system. Once you jump the switch and the clutch engages then you need to check pressures. I am trying to give him a logical path to diagnose the A/C system. If he puts a clutch on it and the compressor is bad then you just wasted the Money on the clutch as most compressors come with a clutch already installed.

Right, but he asked about his clutch originally to which I was referring to. You don't need a charged system to test an AC compressor clutch. I have jumped multiple compressors on completely evacuated systems to test clutches and locked up compressors.

When he said he jumped the switches and it still didn't engage, at that point system pressures aren't going to effect a clutch engaging or not if you're manually jumping the switch to force it to engage.

 

[NskLJ]

Right, but he asked about his clutch originally to which I was referring to. You don't need a charged system to test an AC compressor clutch. I have jumped multiple compressors on completely evacuated systems to test clutches and locked up compressors.

When he said he jumped the switches and it still didn't engage, at that point system pressures aren't going to effect a clutch engaging or not if you're manually jumping the switch to force it to engage.

He also stated he didn’t know anything about A/c systems. That is why I was trying to walk him through a logical procedure of finding the root cause of the failure of the system. So jump the switch it doesn’t work now what? Put a clutch or just the coil on it?

 

[mjonesjr84]

I ordered a new compressor and dryer. The cost wasn't much more than just a clutch.

 

[Cooper Smith]

I ordered a new compressor and dryer. The cost wasn't much more than just a clutch.

Which one did you decide to get?

 

[mjonesjr84]

Which one did you decide to get?

I got a factory reman.

 

[NskLJ]

So the 70 PSI is normal when not running?

I will start tracking it down maybe this evening. I tried getting to the clutch plug without success.

With the engine off rotate the clutch by hand to see if the compressor is locked up. Start the vehicle and remove ac relay jump pin 30 to 87 if the compressor comes on. Swap the relay with another use the horn relay if they are the same. Then check the dash switch and pressure switch circuits to the pcm. If it doesn’t come on check for power at the pin 87 or 30 if you have power. Check the clutch circuit from relay to the compressor. You can use a ohm meter from the pdc to ground (use pin 86 or 30 which ever one doesn’t have power)

 

[Jerry Bransford]

IF the system is so low that the LPCO does not engage the clutch and requires jumping. Instead of adding refrigerant to the system; you should try locating the leak instead of wasting refrigerant.

X2. If the refrigerant is low that indicates there's a leak in the system. They don't consume refrigerant so find the leak by use of a leak-finding dye added to the refrigerant.

 

[mjonesjr84]

X2. If the refrigerant is low that indicates there's a leak in the system. They don't consume refrigerant so find the leak by use of a leak-finding dye added to the refrigerant.

I don't think the system is low on refrigerant since jumping the low pressure switch still doesn't engage the clutch. Per the gauges, with everything off, the gauges showed 70 PSI on both low and high.

 

[CharlesHS]

I don't think the system is low on refrigerant since jumping the low pressure switch still doesn't engage the clutch. Per the gauges, with everything off, the gauges showed 70 PSI on both low and high.

Jumping the LPCO and HPCO and the clutch doesn't engage means you need to troubleshoot further....
Did you verify where the voltage stops in the A/C circuit when going to the clutch ?
Did you apply 12V to the clutch solenoid to see if the clutch engaged ?

 

[mjonesjr84]

Jumping pin 87 & 30 pulls the clutch when the Jeep is running and it blows ice cold air inside. Here are the pressures on the system at idle and not moving.

I've swapped the relay with the horn relay and the horn still works. Where could the disconnect be?