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Negative pressure on Low side

73Wagoneer on Mon March 05, 2012 1:41 PM User is offline

Year: 94
Make: Honda
Model: civic
Engine Size: 1.6
Refrigerant Type: 134
Ambient Temp: 75
Pressure Low: 0
Pressure High: 150

Last year, I replace the acumulator (leaking), expansion valve preventive maint. and the desicant, this year wife tried to use the a/c and no cool air, I put the guages on, when the system in not running low side is 40, when a/c is running low pressure shows negative 20, compressor is engage. I suspect expansion valve, but looking for other problems, like I said I replace the expansion valve when I replace the acumulator.


JACK ADAMS on Mon March 05, 2012 4:37 PM User is offline

Bad TXV.. Nothing will cause this to happen unless you have another restriction in the system.

mk378 on Tue March 06, 2012 10:04 AM User is offline

Pressure when not running only 40 suggests the system is nearly empty. After a long period not running, pressure should equalize at the static pressure corresponding to the temperature of the car.

73Wagoneer on Wed March 07, 2012 11:11 AM User is offline

Thanks for the responses, well when I went to recover the refrigerent, there was hardly any, so looking around the engine bay I could not spot any leaks, dye or oil around the connections, so I went ahead and pulled the accumulator, Honda civics are real easy, no pulling the dash, pulled it out and sure enough a leak around one of the expansion valve joints, took it apart put new o rings and some nylog, pulled a vacuum, and now she is good to go.

Thanks everyone

MK378 you were spot on.

in a way I was glad that there was a leak around the expantion valve, it justified me taking the evap out

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