Recently the A/C in my Dakota stopped working. Was working fine and then the compressor only briefly cycled and wasn't putting out cold air. I tried to add R-134a and see what that would do. When recharging, I'd be able to have ~50psi on the low side, but the compressor would still only cycle briefly.

Since then, I've picked up a set of gauges. Yesterday I threw those on and got the following. My suction pressure when the comp is off is about 50-55psi and 5psi while it's running. High side is at 125psi when running and equal to suction when off. Seems like a strange issue. The system will maintain a 55 psi pressure over a period of days, if not over a week. However, as soon as the compressor starts the suction pressure goes way down.

When I refilled the system, it wasn't empty, and it also didn't take much R-134a to get it up to low side pressure of 50-55psi. I have a vacuum pump and was thinking of pulling vacuum on the system. However, my worry is that if the system doesn't leak at 55psi, it might not show signs of leaks at vacuum. Thoughts?

 

High side pressure is awfully low when the system is running.....wonder if the orifice tube blew out.....

 

Thanks, that's what I was thinking too! When the compress is running, I do hear a hissing sound from the area of the accumulator and orifice tube, but I can't find any leaks. Also, if there was a leak, I would've expected the refrigerant pressure to keep dropping.

Is is better to just replace the orifice tube, or whole line that includes it?

 

On that, I am not sure. On some Dodges, the orifice tube is physically a part of the line it resides in, and isn't serviced separately.......