Automotive Air Conditioning Information Forum (Archives)

rojeho on Sun April 22, 2012 8:08 AM

Year: 92
Make: BMW
Model: 318i
Engine Size: 1.9 M42
Refrigerant Type: R134a
Country of Origin: United States

Replaced the compressor and ready to refill with R134a. When I hook up the vacuum pump I get the following:

1. If gauge valves are open and high and low valves closed, the pump is quiet and gauges bottom out and hold
2. With low side closed, if I open the high side valve, the pump gurgles and there is a hiss near the firewall/low connector
3. With high side closed, if I open the low side valve, the pump gurgles and there is a hiss near the firewall/low connector

If just one side was doing it I would wonder if I had a bad o-ring or a bad low connector. With this situation, I need some help.

mk378 on Sun April 22, 2012 8:13 AM

It's leaking there. When you open either valve it pulls air out of the lines in the car all the way around.

rojeho on Sun April 22, 2012 10:39 AM

Why would both lines leak? Coincidence? Or if there is a leak in one would it show up when pumping the opposite side also?

Is there any way to see if it is the gauge fitting/valve rather than the car?

TRB on Sun April 22, 2012 5:19 PM

Adding pressure to the gauge set might provide the answer.

-------------------------

rojeho on Sun April 22, 2012 6:16 PM

How does the evaporator work related to this? When just one side (either high or low) is under vacuum I can hear a hiss at the firewall. If I open both high and low the sound of the hiss doubles. I've removed the connections, reset the o-rings and made sure everything was tight and it's still doing this. What next?

TRB on Sun April 22, 2012 6:22 PM

Considering you have an expansion block on this system. Might check for a leak there. Hissing noise is most likely a leak of some sort.

-------------------------