Automotive Air Conditioning Information Forum (Archives)

EPA570 on Fri September 12, 2014 8:18 PM

Year: 2000
Make: Alergro bus
Model: Motorhome
Refrigerant Type: R134A
Ambient Temp: 90
Pressure Low: 120+
Pressure High: 20
Country of Origin: United States

Hi everyone cool forum,
I am trying to figure out if I am on the right track here with my diagnose of this ac system. This system has sat for a while and I am trying to get it going again. After pressurizing with nitrogen I found a hole in the dryer. I have so far replaced the compressor(it was still compressing ok just the bearing were about gone), the dryer, and txv. I told the whole system apart and flushed everything (evap, hoses, condenser). After I vacuum the system and I try to charge it I get a really high low side and almost no high side. The only thing I can think is the condenser is not completely clean and it putting debris into the expansion valve. It did have a lot of nasty stuff that flushed out (I flushed it with a whole gallon of flush) but after reading on the net it seems most people replace the condenser instead of replacing it. I assume even the smallest of dedri can stop up the valve?

mk378 on Sat September 13, 2014 8:07 AM

The way a compressor works, is based on check valves which let refrigerant flow from the low side to the high side. So the high side can never actually be a lower pressure than the low side. Usually when a situation like yours occurs, it is because the high side gauge hose is not coupling properly to the service port.

Another possibility is that you connected the lines to the new compressor backwards, so it is pumping from high to low.