Thermostat control mounted in the return duct???

[Y Knot]

My ac keeps kicking on and off due to the mounting of the control unit. I have to adjust it to 55 degrees to get to 75 degrees. The reason; the control unit is mounted in the main cabins vent. Has anyone had this problem and fixed it? I am planning on insulating the back of the control unit with foam etc. Any other suggestions, besides the obvious moving it and leaving a big hole….?

 

[Dave S]

That's the normal location but in my experience with my 260DA if the fan isn't constantly running then they don't work well as far as sensing temperature variations. Does your fan run even with the heat pump off?

 

[Y Knot]

no, my ac kicks the fan on. i'm going to try and put some foam insulation and alluminum foil to make a barrier. i'm hoping to do this on wednesday, unless someone has a better way.
as it is now, it works until the unit says 55, but it's really 75. it doesn't take a couple minutes for it to heat up to the room temp and kick back on. i can't sleep with the constant stop/startup noise....and i thought i was a heavy sleeper:smt013

 

[bluebelly]

I had the same boat as you and I know exactly what you are talking about. You definitely need to program the ac unit to constantly have the fan on at all times. This will keep the air circulated and even out the temp differences and that will stop the frequent ac compressor cycling. That constant air passing across the thermostat will solve your problem.

 

[Dave S]

I don't know which temperature controll panel you have but mine is programable and I can let the fan run constantly or I can program it to only run when the heat pump kicks on. Right in my manual though they tell you to move the temperature sensor out of the intake and relocate it near the thermostat if you are not going to let the fan run all the time. So before you do anything else, I suggest you re-program your control panel to have the fan run constantly and see if that takes care of the problem.

 

[fc3]

Do you have the analog controls or the digital ones? The sensor for the digital controls is a small metal pencil that you can mount anywhere.

Best regards,
Frank

 

[Y Knot]

it's a digital control but i didn't see a "pencil" thermometer. i only saw the control unit connected by a phone style cord. i'll try and set the fan first, thanks!

 

[SkippyzAfloat]

The "pencil" that they are referring to is the thermistor. This is what actually does all of the temperature sensing and is usually mounted directly to the a/c unit or maybe in the return air duct. My buddy had this issue on his Cruisers 3870 and we just relocated the sensor away from the a/c unit and it cured the problem of having wild differences between the forward and aft electronic thermostat settings.(Cruisair SMII) This is an easy DIY job and should have you running in under an hour.

Good luck,

Simon