Engine Size: 2.4
Refrigerant Type: 134
Ambient Temp: 95
Pressure Low: 60-70
Pressure High: 225-250
Country of Origin: United States
Got a 1986 Volvo 240. It had been previously converted years ago to 134, I had fixed a leak, evacuated the system and charged it and low side instantly went to 50-60-70 and high side came up to 225-250 as I added can 2 and 3 of 134. So I flushed lines and installed new expansion valve, and receiver dryer, evacuated the system and same thing happened again with the pressures and no cooling.
So I replaced compressor and flushed out the entire system again. Still no cooling. The low side goes up to 50-60-70 instantly when the first can of 134 goes in and as I add the second can low side stays 60-70 and high side goes to 225-250. I also watered down the condenser which brought the high side down to 170-180 but the low side stays the same. I have done many ac systems over the years but I am lost with this one. I point a laser thermometer onto evaporator and I get about 79-82F on a 95F day
I feel if there was a restriction at the evaporator then the low side would be very low as the compressor is seeking gas from the evaporator and if the high side was restricted then the high side would be even higher. So therefor I don't think we have any restriction as when I flushed out the system i didn't get anything but oil, and yes I replaced the lost oil.
Anyone got any ideas??
It sounds like the refrigerant loop is OK on the high side, the pressure dropped with water on the condensor.
I would suspect the low side connection on the conversion fitting. If the schrader is not depressing properly, you can push refrigerant past it to charge, but you will not get a true reading of the low side pressure. This is a common problem, especially with conversion fittings.
Try pressing down on the low side connector while the system is running, and see if the pressure drops. When you first connect a hose, it travels past the place it rests before the balls lock - so you get a shot of refrigerant in the hose, and the gauge gives a "reading".
Laser thermometers are hit & miss with vent temps. Try a stick thermometer instead.
What engine rpm are you testing at? Idle & 1500 engine rpm pressures can be compared for system analysis.
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
I have taken the schrader conversion connections off and used the old original r12 connections as well to see if that was an issue. I get the same readings. Temp readings with the laser thermometer was pointed at the copper coils inside where the expansion valves connects, not inside the vents. I am pointing it directly onto the copper coils. I have also ran it 1400 1500 rpm and the low side drops to 50ish and thats as low as it gets with 1, 2 or even 3 cans of 134.
I am still baffled as to what it could be. The only thing I think it could be is the expansion valve stuck, but why would it do the same exact same thing with the old and new expansion valve. I'm lost
Thanks for your response though.
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