Help with AC system

[1ino]

My 2002 Liberty AC stopped working, all my cars the AC runs all year, I never turn it off.
Anyway I found the high pressure line had some oil residue where the rubber crimp to condenser line covered with dirt, I bypass the low pressure switch but it still doesn’t run.
When I unplug the pressure transducer the compressor will cycle for less than a second.
I checked system pressure and I was at 145psi, ambient temperature around 100, and I assume Freon temperature was around 108.
I have plenty of Freon that I could add to system, but I don’t believe a can is higher pressure than what’s in the system, so I would be charging the can instead until it equalizes
So the compressor runs, it’s not seized, swooped relay and checked fuse, tried to jump out that transducer plug but no changes.
I cannot run the system to check system charge.

 

[DadOSix]

First thing is you need to find that leak. The oil on the HP line is almost a dead give-away.

Any place you see oil on an AC system usually points to the leak.

I made a mistake a few years back with one of the sniffer detectors. I was getting a hit at the rear of the compressor. Sweet - changed it out and in a week , the charge was gone again. That jeep went back with my son to college in the fall and when it came home, I promptly decided the sniffer was pointing to the evaporator coil. Dyed it and flushed thru the heater box, no green stuff, but it tore it down anyway and replaced a perfectly good coil. A week later, no ac again.

My BIL has a leak detector that listens, rather than sniffs. Charge the car with nitrogen and i hear the leak at the rear of the compressor. Just by accident, I passed the snout over the rubber of the hose - right at the bend. No oil, but a wee pin-hole that I never would have found otherwise.

Now - back to you - even with that bit of system pressure, you should be able to do a decent leak check. Be sure to check the high and low ports for leaks at the valves.

 

[1ino]

First thing is you need to find that leak. The oil on the HP line is almost a dead give-away.

Any place you see oil on an AC system usually points to the leak.

I made a mistake a few years back with one of the sniffer detectors. I was getting a hit at the rear of the compressor. Sweet - changed it out and in a week , the charge was gone again. That jeep went back with my son to college in the fall and when it came home, I promptly decided the sniffer was pointing to the evaporator coil. Dyed it and flushed thru the heater box, no green stuff, but it tore it down anyway and replaced a perfectly good coil. A week later, no ac again.

My BIL has a leak detector that listens, rather than sniffs. Charge the car with nitrogen and i hear the leak at the rear of the compressor. Just by accident, I passed the snout over the rubber of the hose - right at the bend. No oil, but a wee pin-hole that I never would have found otherwise.

Now - back to you - even with that bit of system pressure, you should be able to do a decent leak check. Be sure to check the high and low ports for leaks at the valves.

True and I can add dye to the system but still not able to run and circulate.
Last time I tried soap and water that didn’t show anything.
I believe I have a leak, but at the same time it should have ran when the low pressure switch was bypassed, this takes me to something else besides the leak.
I have almost everything to recharge this system even access to nitrogen but I need to find the problem first
The only thing I’m thinking to change out is the transducer switch to see if I can make it run, the AC wasn’t too low because the system was running great

 

[DadOSix]

True and I can add dye to the system but still not able to run and circulate.
Last time I tried soap and water that didn’t show anything.
I believe I have a leak, but at the same time it should have ran when the low pressure switch was bypassed, this takes me to something else besides the leak.
I have almost everything to recharge this system even access to nitrogen but I need to find the problem first
The only thing I’m thinking to change out is the transducer switch to see if I can make it run, the AC wasn’t too low because the system was running great

Ok - i see that.

So - what are your high and low side pressures?

Jeep off - Manifold set blue to low port and red to high. These numbers should be equal with the engine off. And should also be near the outside ambient temp. If you have lower pressures than outside temp, you are low on charge.

The reason I spoke of a nitrogen charge was to pressurize a dead system to find the leak.
With either a sniffer or listener detector.

I agree the dye will not work if you can’t get the system to cycle. Oh and consider that the dye will need to go into a system with no pressure (just like adding the pag oil. No pressure so the refrigerant or nitrogen can push the dye into the jeep.


On your transducer point: Which one are you jumping out? There is a low side - on or near the accumulator, and a high side - inline coming from the condenser.

The low side switch is 2 pins - can be jumpered out. The high side is a transducer - 3 pins,IIRC, and jumpering will not work.

 

[24turbo]

Compressor relay? You can pull it and check for power on the battery power and signal from the switch.

Doesn’t seem like you are low enough on charge to not allow the compressor to start.

 

[1ino]

The compressor clutch relay was swopped out with another, and when I unplugged the transducer the clutch engaged for a second but the control signal must come from computer and that most likely I did not have, I guess in reality I can force the clutch to engage.
I have a new pressure transducer on the way, I only checked the pressure on the high side, I assume it should have been the same as low side with system not running, 145@108 degrees.
I could add dye into the system under pressure but I need it running to do this, when I get it running I will be doing so to find this leak.

DadOSix: The low side switch is 2 pins - can be jumpered out. The high side is a transducer - 3 pins,IIRC, and jumpering will not work.​

I did jump out the low side and the transducer but that one as you state cannot be jumped out, I take it it is only for computer feedback
I had to charge my home system with nitrogen but for removing impurities before charging, dye was injected with system running and the leak was on brazed capillary tube, easy access.
Anyway I am working till Wednesday hopefully that transducer arrives by then, if not I might still jump out clutch make it run.

 

[Ohio-white-kj]

My compressor went out, turns out the fan is 2 speed and the low speed failed. That caused the compressor to die. After replacing it lost charge, high side hose was leaking (your probably is also).

Was told - it takes little for the compressor to fail, any overheating will do it. If the compressor is shot, your low side will have excessive pressure.

 

[1ino]

My compressor went out, turns out the fan is 2 speed and the low speed failed. That caused the compressor to die. After replacing it lost charge, high side hose was leaking (your probably is also).

Was told - it takes little for the compressor to fail, any overheating will do it. If the compressor is shot, your low side will have excessive pressure.

What is excessive pressure when the refrigerant charge is supposed to be a certain pressure based on ambient temperature, I would think if your pressure is low for the temperature stated in the chart, then system is under charged, anyway I have a new transducer comming hopefully the next couple of days and will try that.

 

[DadOSix]

I cant recall. Are you reading low side with a manifold set or going off the gage on a charge can unit?

 

[1ino]

I cant recall. Are you reading low side with a manifold set or going off the gage on a charge can unit?

I have a couple of manifold sets, I did not connect to low side and I expected the same pressure

 

[Ohio-white-kj]

What is excessive pressure when the refrigerant charge is supposed to be a certain pressure based on ambient temperature, I would think if your pressure is low for the temperature stated in the chart, then system is under charged, anyway I have a new transducer comming hopefully the next couple of days and will try that.

From memory - low side 20-25. Mine was over 100 with a worn compressor.