Could this be..Really??
Thread Starter
Drifting
Joined: Sep 2001
Posts: 2,467
Likes: 16
From: redmond wa
Could this be..Really??
No such thing as refrigerant leaks (strickly) due to "non-barrier" hoses.......
My '92 R/awd Ford Arrestor, front + rear A/C, was just in the shop being converted to R134a refrigerant. Normal charge has been ~$160, this time ~$200.00. Difference was due to having to replace leaking o-rings on the rear of the Sanden compressor, something having to do with the refrigerant OVER-pressure relief valve.
Say WHAT..??
According to the Ford factory manual if the refrigerant pressure rises to high then the valve opens to atmosphere to bleed off refrigerant, but then "resets", closes, to preserve the system integrity. With the A/C compressor clutch controlled by a binary pressure switch why would the system ever go over-pressure?
The answer would be an inadvertently overheated engine, cooling system, radiator, heating up the nearby A/C condensor and thereby raising the internal liquid refrigerant pressure. While I am by no means stating this as a definite answer for the reason our air-cooled Porsche's consistently lose refrigerant, it most certainly has a ring of truth to it.
Drive our Porsche's HARD on a HOT day, making full use of the A/C, and now shut down the engine. How high would the pressure go in the rear lid condensor, overall high side, with all that engine heat rising up through the rear lid condensor.
From what I could find on the INTERNET most automotive A/C compressors included an over-pressure relief valve, at least up until venting R12 to atmosphere was outlawed.
Could this be the real, actual reason, our refrigerant charge only last 2 years? The stage is certainly correctly set.
My '92 R/awd Ford Arrestor, front + rear A/C, was just in the shop being converted to R134a refrigerant. Normal charge has been ~$160, this time ~$200.00. Difference was due to having to replace leaking o-rings on the rear of the Sanden compressor, something having to do with the refrigerant OVER-pressure relief valve.
Say WHAT..??
According to the Ford factory manual if the refrigerant pressure rises to high then the valve opens to atmosphere to bleed off refrigerant, but then "resets", closes, to preserve the system integrity. With the A/C compressor clutch controlled by a binary pressure switch why would the system ever go over-pressure?
The answer would be an inadvertently overheated engine, cooling system, radiator, heating up the nearby A/C condensor and thereby raising the internal liquid refrigerant pressure. While I am by no means stating this as a definite answer for the reason our air-cooled Porsche's consistently lose refrigerant, it most certainly has a ring of truth to it.
Drive our Porsche's HARD on a HOT day, making full use of the A/C, and now shut down the engine. How high would the pressure go in the rear lid condensor, overall high side, with all that engine heat rising up through the rear lid condensor.
From what I could find on the INTERNET most automotive A/C compressors included an over-pressure relief valve, at least up until venting R12 to atmosphere was outlawed.
Could this be the real, actual reason, our refrigerant charge only last 2 years? The stage is certainly correctly set.
Last edited by wwest; Aug 31, 2012 at 03:06 PM.
