Marine AC Issue

[TClark-FL]

Hi, I have a recently acquired 84 Trojan F-36 with factory Cruisair in Cortez, FL. One of the units unexpectedly stuck in reverse cycle and is producing heat but I have not been able to locate a reverse cycle switch. Any ideas? Thanks.

[Coolerking]

Will it go into cool, but not cool?
What type of display/tstat do you have?
Have you set it to heat only in the programming?
Have you lowered the setpoint below ambient?
The reversing valve is on the condensing unit itself, it is a solenoid style, it has a coil with 2 wires which slides over the valve plunger, when it is energized it actuates the plunger which in turn switched the flow of refrigerant, effectively turning the seawater condenser into an evaporator.
Look for the coil and a big tube with 3 other tubes coming out.

It may be stuck, you can tap it (the big part) lightly to try and free it up, but be careful.
There many other things that cause this, but try and get us answers to the questions above and we can figure it out.

[EngNate]

The rev cycle is switch is part of the thermostat and is controlled by the temperature dial. It is fairly common for the reversing valve to stick from disuse. It usually can be freed by cycling the temp dial from lowest to highest setting several times with the unit running. Note, the room temp must be within range for both heat and cool settings for this to work. Also check the connections at the reversing valve. This is a piece in the refrigerant plumbing that looks like a tree with 4 copper tubes coming into it and an electric coil on the end.

[a64pilot]

You can actually wack one pretty good with the handle of a plastic screwdriver, just don’t use a sharp edged metal tool.
If it operates, you’ll hear an unmistakable Whoosh as the gas changes paths.
Before you do anything though, find it and have someone actuate the thermostat full range and wait for say 1 min at each full range, at one of those you should hear a click, that’s telling you the solenoid is getting power and the solenoid is stuck if you don’t hear that Whoosh.
If it doesn’t click at all, then you may have an electrical problem, if it clicks but no whoosh, the reversing valve may be stuck.
I believe it’s usual for the no power condition to be cooling and it takes power to cause one to go to heat.
Stuck reversing valves are pretty common as they can sit for long periods and eventually get stuck, very often a percussion adjustment gets them working again.

Personally for some reason, I’ve not heard of one getting stuck in the heat mode, not sure why though, but they always seem to stick in the cooling mode. Maybe that’s because when not operating they return to the cooling position as that’s where the solenoid goes when power is off, at least for the ones I’ve had.

[GordMay]

Greetings and welcome aboard the CF, TClark.

[TClark-FL]

I located the reversing valve and tried tapping but it does not change the behavior. I tried cycling the temp control also with no luck. Also, I noticed cycling the temp control causes a whooshing noise from pump/condenser unit. I did notice one very strange behavior when cycling the temp control - when set to coldest, it is hot and when set to warmest it is room temp. I have attached an image of control panel. Thanks for all the info.

[a64pilot]

That whoosh noise is the reversing valve doing its thing.
That control panel looks very close to my old one, I replaced the thermostat for a stupid price once I found it once and eventually replaced the whole unit.

But if you heard the whoosh, I’m pretty sure the reversing valve works, and your problem is elsewhere.