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a/c replacement pressure problem

stija on Mon August 31, 2009 12:47 AM User is offline

Year: 1996
Make: ford
Model: escort lx
Engine Size: 1.9L
Refrigerant Type: 134a
Pressure Low: 40
Pressure High: 350+

1996 ford escort 1.9lx 5spd in question.

I've had a catastrophic a/c failure and decided to replace EVERYTHING BUT EVAPORATOR (it was only flushed), and so I did.

When hooked up it was running at 30-40 low end and 350+ high end on idle. When driving or under throttle it would surge above 400 and turn off.

My hypothesis was that there was too much of something in there even though we followed instructions to the letter. So I had my mechanic take out 0.5lbs of refrigerant and it still ran at 350psi. So it definetly is NOT TOO much oil/refrigerant.

My mechanic suggested we replace the compressor with a new one (i had bought a remanufactured one). I was hesitant but said what the heck, can't argue with the guy since THEY are the mechanics.

We put a new one in after flushing all the new lines again. Same thing happened. High end pressure was ~380 under idle and above 400 when driving or under throttle.

Mechanic thought the condenser was bad and checked it for cold/hot spots but it turned out fine. Now we are out of ideas.

Anyone have any ideas? Clues? Same thing happen to them?

Also, what does the high pressure transducer do? Is its function to only shut off the compressor under high pressures or does it actually control/maintain the pressure?


Edited: Mon August 31, 2009 at 12:48 AM by stija

mk378 on Mon August 31, 2009 7:59 AM User is offline

Did you get all the flushing agent out? Was the system evacuated with a vacuum pump before charging? Do the condenser fans work? Is your new condenser the same as the old stock one?

Definitely couldn't be the compressor, no problem with a compressor that can make 400 psi.

High side pressure isn't actively regulated, other than possibly the computer using the transducer to cycle the condenser fans on and off. That should occur in the low to mid 200's. Once above that pressure, the fans should be on constantly. Shutdown due to high pressure should never occur in normal operation.

Chick on Mon August 31, 2009 11:12 AM User is offlineView users profile

Your car uses a cycling switch (two wire) not a transducer (three wire) Pull the O tube and check for debris, you have a blockage of fan(s) not operating properly..You car also has a CCRM ( relay control module) and it may not be turning on the fans.. As stated above, there is nothing wrong with the compressor you have if it pulls suction, and pushes out pressure....

Email: Chick


Freedoms just another word for nothing left to lose

stija on Mon August 31, 2009 6:06 PM User is offline

I believe that my car doesn't have the CCRM. The newer model escorts do though.

You are right about the two wire connector. To be honest I don't remember if the fans were on constantly as they should have been at 350+psi. I will call and find out from my mechanic.

The flush was performed by my mechanic, and I trust that he has done it properly. The vacuum was done properly as well before recharged. The condenser looked the same as the old one.

They told me today that we could have possibly used a different orifice tube even though we used the same color that we took out. They are checking into that. I will report back of any changes or breakthroughs.

stija on Mon August 31, 2009 6:14 PM User is offline

The fan is working properly, just spoke with the mechanic who assured me that was the first thing they checked.

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