What should the R134 pressure be on the low side?

thesteve · #1 (**permalink**) 01-22-2005, 10:29 PM

I just refilled my A/C system today going by the directions on the package. It says that for an ambient temp of above 90, the pressure on the low side should be between 50-55 psi. Is this too high for a 1st gen? Even at 40 psi it's much colder than it was before, and the fans are at their highest speed with the A/C on even though the engine is cold. The compressor seems to cycle on and off often (like every 8-10 seconds) even at the coldest setting so I think that the system was not designed for that much pressure. Right now it's at 40psi, I'd like to hear some other input before I go any higher.

danil02000 · #2 (**permalink**) 02-22-2005, 02:06 AM

I have also refilled my ac with R134. I have noticed the compressor cycles very often, and the fans are running at high speed. After a few seconds, the fans turn-off and there is no more cold air. Could this be because there is too much preasure?

thesteve · #3 (**permalink**) 02-22-2005, 02:59 AM

Yeah, I think so. The fans are at high speed most likely because the a/c is putting a huge strain on the engine, as well as creating more heat at the condensor. Then, because of the heavy engine load, the a/c automatically turns itself off causing the fans to turn off.

When I did mine, the instructions said to fill it to 50-55 on the low side while the a/c is on. I only filled it to 40psi, and it ran ok for a bit, but once the car was shut off, the pressure between high and low sides equalized to 90psi. 90 psi is definetly too high (even makes the car almost stall out when engaging a/c) so I just kept bleeding pressure until the fans returned to normal and the compressor stayed on without cycling constantly. Works fine now, a month later.

danil02000 · #4 (**permalink**) 03-17-2005, 02:28 PM

hello,

What is the correct way to bleed the AC to release the preasure? I mean from which valve the one where you put the refill in or the other one close to the fans.

Sorry for such easy question?

thesteve · #5 (**permalink**) 03-17-2005, 05:31 PM

Always use the Low Pressure valve. Unless you have tools specifically designed for the high pressure side, never connect anything to it. I don't remember for sure, but I think the low pressure valve is a thicker pipe, over by the power steering reservoir and the passenger side suspension column. The valve cap for the low side will be marked with a large L printed on top of it.

To bleed it, attach the refiller hose to the car without the can present (make sure valve is closed all the way first). Then slowly open the valve. Be careful, this stuff gets cold when depressurized, and if it has any of the dye in it to find leaks, that stuff will be shooting out everywhere.