Marine Air Compressor Problem

General Discussion
1

My boat has been sitting in San Diego since November. At that time the AC was working fine. We just returned and found that the AC wasn’t cooling or heating.

I put gauges on the compressor and saw that I wasn’t getting any compression. I thought that perhaps that I had a leak, so I vacuumed the system, but found that it held the vacuum overnight. I then recharged and once again saw that I wasn’t getting any compression when cooling. I then ran some tests and am quite confused by what I’m seeing.

In cooling mode, I see the low pressure side reading decrease as expected, but I see no pressure increase on the high side. When I put it into reverse cycle heating mode, I see ~115 PSI on the suction side, but there is no pressure decrease on high side as measured at the rotolock valves on the compressor.

The compressor is clearly generating compression as shown by the heating cycle. I’m absolutely stumped as to why I see no changes in pressure at the high pressure rotolock valve. My guess was that somehow or another the condenser loop was clogged, but then you’d expect the pressure reading to be effected one way or the other by the suction side.

Any bright ideas?

– Geoff

2

This may seem obvious, but, make sure your rotolock valve is mid point. Not front seated or back seated.
I have made this mistake before and over charged the system, thinking there was no head pressure.

regards,

van

3

I found out something that I didn’t know…that the gauge ports on the Marine Air system have Schroeder valves and they’re located facing backwards in a location that I can’t see. My refrigeration system doesn’t have Schroeder valves. Anyhow, due to access restrictions, I had reversed the HP hose so that the end with the pin which depresses the Schroeder valve was at the gauge end! Duh…Won’t make that mistake again.

Anyhow, after figuring that out I was able to get good readings and rectify the issue.

Thanks for the suggestion.

– Geoff