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duncan_ellison · 06-06-2019, 08:02

Hi all, any experts on Marvair / Seamach A/C units lurking here?

Scenario: I have 2 x 16,000 BTU units on my boat which share a single circulation pump. Boat has been on the hard for a few years and I re-commissioned her a few weeks ago.

Forward unit runs like a champ, aft unit wasn't getting cold and kept tripping the breaker when turned on. Sometimes, it would eventually run, but didn't seem to be getting very cold.

Had an A/C tech look at it and he determined that the low side of the system had an abnormally high pressure, so he let out quite a bit of the R22 (legally of course

) and the vapour pressure dropped and it started making cold again and seemed to be running reasonably normally.

Situation now is that the unit runs and gets cold nicely once it's been persuaded to start up. Lots of sweat on the evaporator and gets reasonably cold.

From a dark start, the compressor makes a noise like it's trying to run (like 'mmmmmmmmm') then some safety device cuts in after only 3-4 seconds. There's a noise like '...TOK...' as it does so.

Then it tries the cycle again between 4 and 8 times and (usually) starts up then runs normally.

I don't think it can be the motor overheat protection that the tech mentioned as the motor is still cold at that point.

I'm thinking maybe a motor capacitor, but I don't even know where to look for that.

The tech told me to basically put it in the skip and buy a new one, but at $2K+, that's not really an option at the moment. Plus I would have to change out the control panels etc.

For reference, the unit is SPB16RCBL manufactured by Airxcel vintage approx 2006.

Can anyone give me any useful pointers ?

Duncan

goldenstreak · 06-06-2019, 09:13

I have never worked on a marine air system. However I have over 20yrs in the field of refrigeration and hvac.
Yes, change the capacitor. But see if there is a hard start package for it. I think Marvair calls it an SPP- starter power pack. I believe this is most likely to help the situation. I wouldn't expect this to keep a unit that old running for more than a few seasons. Also make sure all the connections between the compressor and board are tight.
Depending on if the system is split and locations of the evaporator some oil may have logged there away from the compressor so adding some oil to the compressor may help but that's a long shot and the amounts to add would be a guess. The locations of the components I can't help you with, I would expect them to be mounted close to the compressor in a box.