I have a Cruisair model WFAH12 12000 btu ac unit on my sailboat and it seems to be stuck in heat mode.  It is an older one with the manual dials.  It worked great for the last two summers, but this year will not go out of heat mode no matter where the "colder" dial is.  Any suggestions on which part I should be looking at to replace?  At first I thought it just was not hot enough for the thermostat to switch over, but lately it has been close to 90 degrees inside the cabin.  Any advice would be greatly appreciated.

Hey Steve,  Thanks so much for the helpful advice!  I did what you asked and the unit cooled great last night (about froze my ass off but who's complaining).  I have a wholesale account here locally and will pick up a new thermostat tomorrow.  Thanks again for the great advice! 

CACOKER said:

Hey Steve, I am now going to truly show my ignorance.  When you said I need a new thermostat, does that mean the dial that I turn to go from cool to heat, Yes… or do you mean the electronic device inside of the electrical box cover that the copper sensor terminates into? No…From your description that sounds like the High Pressure switch Or  do I need to replace something entirely different?  Another piece of advice would be greatly appreciated!Thanks!

The thermostat is the bottom knob on the control…It's not just to select cool to heat, but can be set to maintain a certain cabin temp (even though it does not have numbers) It has a small tube that runs from the back of the control to the air handler return air path where you find it has a larger tube…The larger tube senses the air temp as it passes by.

Steve~