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AC Compressor Ideas

Wiser

Wiser

NAXJA Forum User
Location
92345
1991 4.0L AW4 4x4

Looking for some ideas on what to be checking and testing so I can get my AC going for summer. Prior to having the system looked at, it blew warm air.

Went to a guy that charges R12 systems and he tried to charge the system but said that the AC compressor wasn't taking in the freon and more than likely it was toast. So I come back home and SEARCHED. I tested the clutch by giving it direct 12 volts and it engages fine. With the jeep and the AC ON, I got a multimeter and tested to see if I was getting 12v at the clutch wire but I WASNT. So then I swapped the AC relay with the starter relay (known to be good) to see if that did anything and still no juice going to the AC clutch wire. Any other ideas for testing? NOTE: The system did have a small charge in it before the AC guy evacuated it. Thanks👍🏻
 
As far as I recall your system has a cycling switch inline. It won't trigger the AC clutch if there's no pressure in the system.
 
hawkeye 1 said:
As far as I recall your system has a cycling switch inline. It won't trigger the AC clutch if there's no pressure in the system.
Click to expand...
I'm thinking my next step would be to try and charge it again with enough freon to run the compressor? Or is there a way to bypass to switch and see if I can get 12volts to the clutch?
 
The switches are normally open and close when appropriate. You can jump all of them to make a close circuit and see what's going on. A set of gauges is real helpful here.
 
Yep, as md21722 said you can jump the switch to engage the compressor.

I don't know what the guy testing it did, usually when freon is hooked to it the pressure switch will trip engaging the compressor. But I've had it where that didn't work on the jeep so I'd just jump it. That's my first thought why it didn't take freon.

You can have a bad pressures switch , problems in the line, dryer, condenser, evaporator.
You can use r134a instead but if you know the system has r12, it's a better freon for this jeep but you can convert it if you have to.




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Green Mesa XJ said:
Yep, as md21722 said you can jump the switch to engage the compressor.

I don't know what the guy testing it did, usually when freon is hooked to it the pressure switch will trip engaging the compressor. But I've had it where that didn't work on the jeep so I'd just jump it. That's my first thought why it didn't take freon.

You can have a bad pressures switch , problems in the line, dryer, condenser, evaporator.
You can use r134a instead but if you know the system has r12, it's a better freon for this jeep but you can convert it if you have to.




Sent from my iPhone using Tapatalk
Click to expand...
Thanks for the reply. I'll check into the pressure switch. is that switch inline on the low pressure side? From what I've been told, I have the "ford style" fill ports and valves on my xj AC system. I was looking at getting the Conversion fittings for 134a but Not sure what to get.
 
Green Mesa XJ said:
I'll look at my jeep in a bit. I thought the switch was near the dryer.

Any conversion kit should have the correct adapters


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Click to expand...

Thanks Mesa XJ, I'll have to get a picture of my xj AC system posted up to get a better idea
 
Here is the switch, look below the back of the compressor
e527b29633211118557e523dab395f88.jpg


And here are the r134a ports, lost the caps a long time ago I believe low side was at the top
7711613a33f78dbc7d254bfac90ad3d6.jpg
1ef70157c92200be129fde0194378da6.jpg



Sent from my iPhone using Tapatalk
 
Never heard of it before, but I have not doing any new AC work the last few years. What is in your system now and what fittings are on it now?

R-12 fittings are small threaded fittings, the R-134a fittings are large bulky quick disconnect style fittings that might have been installed on yours already in a change from R-12 to R-134a?

Is yours still using R-12?
 
I never heard of it either. Gave up on r12 when it was no longer available in stores. Red tek is new to me
Seems like it could be ok.


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Ecomike said:
Never heard of it before, but I have not doing any new AC work the last few years. What is in your system now and what fittings are on it now?

R-12 fittings are small threaded fittings, the R-134a fittings are large bulky quick disconnect style fittings that might have been installed on yours already in a change from R-12 to R-134a?

Is yours still using R-12?
Click to expand...
My system is r12. I'll get pics tomorrow when there's light out.
Green Mesa XJ said:
I never heard of it either. Gave up on r12 when it was no longer available in stores. Red tek is new to me
Seems like it could be ok.


Sent from my iPhone using Tapatalk
Click to expand...

From the reviews, seems like a good alternative.
 
Sorry in advanced if these pictures are huge. I can't tell if they post large on my phone.


 
Looks like the factory r12 fittings. 90% it's still r12, but those r-34a kits have been around so long you never know if a car lot "topped it off".

Were you able to jump it?

Looking at that compressor it reminded me the reason I replaced the original compressor a few years ago was it was leaking from the from seal, so if you do get it to run when you turn it off look around the front for any thing slowly bubbling out


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Green Mesa XJ said:
Looks like the factory r12 fittings. 90% it's still r12, but those r-34a kits have been around so long you never know if a car lot "topped it off".

Were you able to jump it?

Looking at that compressor it reminded me the reason I replaced the original compressor a few years ago was it was leaking from the from seal, so if you do get it to run when you turn it off look around the front for any thing slowly bubbling out


Sent from my iPhone using Tapatalk
Click to expand...
I haven't jumped it, I'll try in a bit. So just a recap. By jumping the pressure switch, it should engage the clutch on the compressor, right? Will any conversion kit work with these types of ports?
 
Just jumped the low pressure switch and the clutch engaged as it should with the jeep ON. Also getting 12-13v to the clutch. I guess I'll be getting a new pressure switch and conversion kit. Hopefully that takes care of my issues!
 
Those are the factory R-12 fittings, and on the drivers side is a cap hiding a valve handle that needs to be opened to add or remove refrigerant and to get live pressure readings. That is why he is not getting the pressure switch to turn on the clutch when he tries to add refrigerant. I doubt you need a new pressure switch.
 
Last edited:
Ecomike said:
Those are the factory R-12 fittings, and on the drivers side is a cap hiding a valve handle that needs to be opened to add or remove refrigerant and to get live pressure readings. That is why he is not getting the pressure switch to turn on the clutch when he tries to add refrigerant.
Click to expand...

He was turning those valves (they were kinda hard to turn) as he started to introduce freon into the system. I also noticed the clutch never engaging as we were trying to add the freon.
 
Who ever you used did not know what he was doing. He missed the old style valves that need to be opened to get the refrigerant into the compressor so the pressure switch can see the pressure from the fresh refrigerant. He may not have been around long enough to recognize the 25 year old (obsolete since about 1992) valves.

Wiser said:
1991 4.0L AW4 4x4

Looking for some ideas on what to be checking and testing so I can get my AC going for summer. Prior to having the system looked at, it blew warm air.

Went to a guy that charges R12 systems and he tried to charge the system but said that the AC compressor wasn't taking in the freon and more than likely it was toast. So I come back home and SEARCHED. I tested the clutch by giving it direct 12 volts and it engages fine. With the jeep and the AC ON, I got a multimeter and tested to see if I was getting 12v at the clutch wire but I WASNT. So then I swapped the AC relay with the starter relay (known to be good) to see if that did anything and still no juice going to the AC clutch wire. Any other ideas for testing? NOTE: The system did have a small charge in it before the AC guy evacuated it. Thanks👍🏻
Click to expand...
 
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