AC Thermostat

grouch0jr

The AC on my boat cools just fine, but the thermostat doesn't read the ambient temperature correctly. It's probably 80° in the cabin, but the display shows 67. This is a problem because it only lets me adjust the setpoint to a minimum of 65, so it's uncomfortable. It's a Marine Air Systems unit, like the image attached. Is there a way to recalibrate this? Anyone else have this problem? 

grouch0jr

Ok, I feel super silly for posting this, I was able to figure it out on my own immediately after posting. I found the manual online and was able to put the control panel in "program mode", then adjust the Temperature Sensor Calibration (parameter #5). I added 10 degrees to the "measured" temp, and now it's working as expected.

captkevin

It was always great when you find a quick & easy solution. Congrats

rasbury

And I was pulling out the manual...

MarkB

The difference in temperature measurement can easily be just because of where the thermocouple is located.  Often they put it just behind the air intake filter (and the AC unit is right behind that). If the thermocouple is close to the coils (cold part of AC), then it will artificially read low.  The thermocouples normally come with a long wire, so you can actually relocate it to a more representative area.

rasbury

That's where mine is on the filter..the 270 cabin is such a size that ac works perfectly....

aero3113

Mine is on the filter on the unit as well. When I replaced the system a few years ago it came with a longer sensor wire. I haven’t used it but have been wondering if I should for more accuracy. Where do most put it if they use the longer sensor wire? 

aero3113

Maybe at the intake filter? Not on the filter on the unit?

grouch0jr

Mine worked perfectly for all last season and the first half of this season. I doubt sensor placement would cause this issue to suddenly present itself, but I'll definitely investigate it, maybe it came loose or something.

Typically you'd want the sensor to be measuring the actual space. The return air stream is the next best location. My intake filter is down near the floor, down there it would always measure a few degrees lower, especially because it's right near the supply register.

Dream_Inn

aero3113 said:

Maybe at the intake filter? Not on the filter on the unit?

Yep, this is where it should be and where I have mine.

Spyderweb

I believe I had moved mine near the intake filter.  Seemed much more representative after that.