Cruisair 12K BTU split system gives "LO PS" error but only on heat mode

[Dune]

Works fine in cool mode. About 2002 vintage unit, which was icing up the evaporator coils (dual evaporator/fans on this one) early summer so had some R22 added, which cured that problem and it cooled fine all summer...

And still does on warm days like yesterday. But, put it in heat mode and it goes into low pressure shut down within a minute or two.

Could R22 pressure be right at the verge of triggering the LO PS shut down but more prone to that in heat than cool ? Or perhaps the reversing valve is stuck ? Or ??

 

[DavidM]

First, I wouldn't expect that adding Freon would be the right way to stop evaporator icing. I think all you did was reduce the capacity of the unit due to liquid Freon blocking some of the condenser area so that it no longer iced. The right way to stop icing is to increase air flow.


So, yes I would suspect that your Freon charge is not right. Don't go back to the same guy though ;-).

And BTW I assume that water temps aren't too cold in SC (below 40 F) to cause the LP error.

 

[Dune]

The right way to stop icing is to increase air flow.

Actually the condenser tubing was icing as well...a lot...prior to the freon addition. And the air flow in the evaporator was as good as possible....the coil (radiator looking parts) were clean, filters clean, squirrel cage fans working properly. Also the compressor part of the condenser was running too hot to touch prior to additional freon. All of that fixed with more freon.... but now, get immediate LO PS error in heat mode. (SXII control)

FWIW, the boat has 5 Cruisair condensers. One other one is now giving LO PS error as well but that one does so in both cold and heat mode. The other 3 units work fine in both modes.

I have had HI PS errors in the past but they were always due to clogged raw water intake strainer and effected all 5 units. Strainer looks pretty clear now.

 

[Scary]

Water temperature plays a roll in R22 pressure. You probably need refrigeration guy familiar with Cruise air to get correct pressure. Reversing valve works or doesn't.