Hello Steve, first I would like to say that this has to be the single greatest resource for marine air systems on the entire web. I can only imagine the incredible effort needed to maintain the site. Sincerest thanks, with such support why would anyone buy an A/C unit anywhere else. I have what I hope is an easy question for you…… but first…

My system: Marine-Air VRE12KH with ECU control (1990-91) 12,000btu. An aftermarket unit not presently installed in boat, usage fresh water Great Lakes Canada. The ECU control is dead & the entire unit is currently on my work bench to test the comp/fan/evap/condenser assy to determine if it is worth upgrading the control. The unit was rarely ever used & is virtually indistinguishable from new. It has not been turned on in 10 or 12 years. At the moment I have the compressor and fan jumpered to the 120VAC line and feeding the cooling water via a garden hose.

My question: While in cooling mode, the compressor runs slightly & evenly warm but when I manually power the reverse solenoid to switch to heat mode, it does start blowing 'somewhat' warm air, the condenser gets ice cold, but I note that the compressor starts to get hot within 1 or 2 minutes. (By hot I mean uncomfortable to hold your hand on it anymore) I do not know if it will get even hotter if let run longer as I was fearful of damaging the compressor. Does this sound normal to you?

One other thing I noted (and may or may not be relevant) was that in cooling mode there is only a 10 degree difference between the return air and the fan outlet. (no ducts connected, measured right at the fan outlet and center of the evaporator)

Any thoughts?

Hi Steve,  Regarding new unit sales, it's because the great wealth of info on this forum is resulting in many units being put back into operation that would……. should? otherwise be junked.

I checked the link provided and it is the rotary style, am delighted to hear these normally run hot. Is there any sort of benchmark/generic operating temperatures on these rotary compressors? I see what appears to be a thermal switch on top of the compressor, is it safe to assume this will shut down / protect the compressor if it gets too hot operationally, (I would love to leave it in heat mode for awhile to be sure there is in fact no problem), or is this switch simply to prevent on-board camp fires. ie: too late for the compressor if it opens.

I obtained the 10 degree TD using a digital thermocouple meter, measuring one then the other. I will let it run longer in cool mode and see if TD increases. I think I read in another post on the forum that a low TD could be the result of low refrigerant?