Weird AC arrangement...???

On our new-to-us 44' Trojan, there are two reverse cycle marine AC units. Both of the compressors are located next to each other on starboard side of the engine room, and the water pump is in the forward bilge area under the galley floor.

The main unit controls are located in the saloon and has the start/run switch, the fan low-high variable speed knob, and the temp setting knob.

The second unit with the same controls above is in the aft (main) cabin. In the forward V-birth cabin, there is another unit that just has a variable fan speed controller knob. This blows only when the saloon unit is operational.

Here's the weird part... at least to me.
If I turn on the saloon unit to cool, the V-birth fan turns on but it just blows room temp air, it never cools. If I turn the aft cabin unit to run, the V-birth will then cool incredibly well. If I turn off the saloon unit, no air to the V-birth. Seems to me a fan control switch is crossed up somewhere, but I wanted to throw it out here first. I would think that if both cabins were being fed by the same compressor, both fan switches should also be off that unit, not one being activated by each.

So basically, I have to operate both systems to cool both cabins at night, even though it appears that both cabins are serviced by the same compressor... I'd like to be able to just have just the cabin(s) compressor on at night leaving the saloon off.

Anybody have any ideas?

Thanks!

Your suspicion that the blower leads are miswired sounds correct. I'm guessing the cabin areas are both served by the same condensing/compressor unit that has a split line set. The control box in the aft cabin controls the condenser/compressor. The relay box at the compressor/condenser unit should have terminals marked "fan" that power the remote fan coil unit. It sounds like someone wired the fan leads for the v-berth unit onto the fan terminals of the saloon unit. Just relocate the fan leads from the saloon unit to the aft cabin and Bob's your uncle.
Make sure they're all the same voltage- that vintage they're probably 115V, but verify. Shut them off to do the wiring. The two relay boxes should be the same, so it's a matter of reconnecting the same way on the other box.

Maerin said:

Your suspicion that the blower leads are miswired sounds correct. I'm guessing the cabin areas are both served by the same condensing/compressor unit that has a split line set. The control box in the aft cabin controls the condenser/compressor. The relay box at the compressor/condenser unit should have terminals marked "fan" that power the remote fan coil unit. It sounds like someone wired the fan leads for the v-berth unit onto the fan terminals of the saloon unit. Just relocate the fan leads from the saloon unit to the aft cabin and Bob's your uncle.
Make sure they're all the same voltage- that vintage they're probably 115V, but verify. Shut them off to do the wiring. The two relay boxes should be the same, so it's a matter of reconnecting the same way on the other box.

Click to expand...

Thank you Maerin, for your input. We didn't notice the issue until recently when our daughter came to stay with us until college starts up for her Sept. 9th... I'd shut the aft cabin unit off in the evening when we were all watching TV since nobody is in there, and before long, her V-berth would get hot.

I'll look at the fan wiring tonight.