Quote:
Originally Posted by kuehl
Ok, that might be a theory. So prove the theory!
Assuming a stock 911 (SC or Car):
1) What is the average high side and low side pressure when the system is not running; you walk out to the car in the morning, you have not started it up.
It's 90F outside. What are the pressures?
2) What is the average high side and low side pressure when the system is operating (engine running, compressor engaged), with either R12 or R134a, say at idle,
90F outside?
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"..So prove the theory!.."
You already did that...
You said that legacy systems that included refrigerant pressure relief valves, "fuses" required the addition of a hi/lo pressure switch when converting to R-134a to prevent inadvertent, no system failure, tripping of those relief valves.
Seemingly R-12 systems have an expectation of a system failure leading to excess pressures higher than 450 PSI. What might those expectant failures be and what might be the parallel expectant failure for our Porsche's that have no pressure relief valves....?
Capillary tube/bulb not properly, fully, inserted into the evaporator core...?
Capillary tube/bulb function failure due to loss of internal charge?
TXV malajusted or drifted out of tolerance, full restrictive level at 34F, and thus prevents the evaporator core from ever declining to the 28F thermostatic switch "off" setpoint?
Continuous demand for 34F vent temperatures, evaporator continously near freezing and with TXV mostly closed. How high might high side pressures get when the compressor runs "open loop" (no pressure level feedback) with those conditions existing continuously for hour after hour..?
Close to maximum system component design specifications...???
Now turn off the ignition out in the HOT August Texas sun.