HELP Troubleshooting A/C

[Alaskan Sea-Duction]

On my boat I have two Marine Air reverse air A/C-Heating units. I guess they are now Dometic. One unit is for the front, the other is for the aft.

The compressors are located in the engine room. Then the fans and radiators are located in a cabinet in front and back.

The rear unit thermostat knob was stuck. I installed a new one. Turned the unit one and only cool air comes out. Move the knob to cold and I get freezing air out. Turn the knob to heat and you can hear the switch turn and after a few minutes no cold air, just slightly warm. I can put my hand on the side of the radiator and it warms up a little when the knob is on heat and cold when turned to cold. (Front unit runs good with hot and cold air.)

I go below with both units on. The unit for the front, the compressor is cold to the touch. The compressor for the rear is hot to the touch. When the wife turns off the rear unit, it shuts down with a relieving pressure sound.

Something is going on with the compressor.

I have included a few pics. Any ideas?

 

[Crusty Chief]

Time to get the portable heaters out, and find a good service tech, I’m thinking the compressor is wore out.

 

[Maerin]

Without some baseline troubleshooting, presuming the compressor is shot is jumping to conclusions. It could be a relay, capacitor, loose terminal, any number of electrical problems, any of which could cause the compressor to no-show. All of those electrical problems are relatively easy fixes, and parts are ubiquitous and won't break the bank.

Find a reputable tech to DX the system before making wild assumptions. Good service and cheap typically don't occupy the same space.

 

[ranger58sb]

The rear unit thermostat knob was stuck. I installed a new one. Turned the unit one and only cool air comes out. Move the knob to cold and I get freezing air out. Turn the knob to heat and you can hear the switch turn and after a few minutes no cold air, just slightly warm. I can put my hand on the side of the radiator and it warms up a little when the knob is on heat and cold when turned to cold. (Front unit runs good with hot and cold air.)

I go below with both units on. The unit for the front, the compressor is cold to the touch. The compressor for the rear is hot to the touch. When the wife turns off the rear unit, it shuts down with a relieving pressure sound.

Something is going on with the compressor.

Our Marine Airrrrrrr unit is newer than yours, with Passport II control instead of knobs, etc... But two ides come to mind.

First is that the "relieving pressure" sound you're hearing on the other one may be the reversing valve doing it's thing. If you're not hearing that with the failing unit, that valve might be part of the problem. I've read whacking it (lightly?) with a mallet might help. YMMV, though, in case all that does is break it. Given that you have cold but not hot, I'd guess the reversing valve is most likely (part of?) the problem. (I dunno what a reversing vale looks like, nor where it lives...)

The other thought is that when we had an issue with the compressor not starting on one of our units... it turned out that taking the leads off the compressor, cleaning all that up, and reinstalling fixed it. So... you might try that, maybe first since it seems less potentially destructive than that whole mallet thing.

-Chris

 

[Alaskan Sea-Duction]

Time to get the portable heaters out, and find a good service tech, I’m thinking the compressor is wore out.

Who would you recommend?

 

[Crusty Chief]

Who would you recommend?

Give Jimmy Palmer a call, He should know a good guy if he cant do it. He’s my go to guy on the Hydronic heat, but that’s a different animal.

Shoot me a text if you need his number.