Cruise Air Thermostat

[rspahr]

when we turn on our cruise air ac the thermostat indicates 91 degrees F and then clicks down to about 10 degrees. As the temp clicks past our ac temp setting of 76 degrees the ac stops cooling but fans run and blows room temp air., compressor stops as indicated by amps going to zero on main electrical panel.

[a64pilot]

I'm not sure I understand if this is a question, a statement or asking if there is a problem. Let me break down what I think you are saying.

1. You turn on the AC and you get a reading of 91. This indicates incoming air temp of 91 and if the AC is in a warm location is exactly normal.

2. After the fan kicks in, soon the temp displayed shows about 81. This is indicating room temp to be 81 degrees, the ten degree drop may be simply from pulling in cooler air into the ac compartment where the thermostat sensor is., This is completely normal.

3. After hitting the set point of 76 degrees, the compressor stops, but the fan continues to run. Again, correct operation, unlike a house AC, a marine AC's fan runs continously.
I assume this is because of the way the thermostat works, a house AC thermostat measures the temp inside of the room, temp sensor is in the thermostat itself.
But a Marine AC measures the temp of the incoming air into the AC unit, the temp sensor is close to the AC unit, not in the box that you think of and call a thermostat, so the only way to measure the air in the room is to have a constant flow.

If I understand correctly, it sounds as if your AC unit is operating correctly

[rspahr]

Thanks so much for your response Sir. But I miss communicated.
We are in the Bahamas. When the unit is turned on the temp in the boat is about 80 to 85 degrees. The thermostat immediately indicates 91 degrees and then begins quickly clicking down to a reading of 10 degrees in about 30 seconds.

[a64pilot]

The temp sensor that displays that temp is where the AC unit is, I bet money it's 91 degrees in there, but when you turn the unit on it starts pulling in air from the boat that is at a lower temp than 91 so you see the temp drop drastically.
I can only guess that Marine units do not have the temp sensor located in what we mistakenly call the thermostat as it's likely to be mounted in some unusual places and wouldn't be nearly as accurate at reading room temp.

What you describe is from what I can tell completely normal operation.

Two things tough as I assume Marine AC is new to you, first try to make sure the raw water strainer stays clean and clear or it will adversely affect your AC, and secondly keep the air filter and evaporator coil clean and make sure the condensate drain is clear. Some people will spray the evaporator with Lysol when they clean the air filter, to try to keep mold from growing, it seems to help and it's real easy to do.
OK that was four things, sorry

[a64pilot]

You are saying it's 91 to start with, but then quickly drops 10 degrees to a reading of about 81?