Thermostat Calibration?

[Ron & Dee]

Is my basement AC doing it's job or not.

Yesterday with the AC running on a 20 amp service, I stepped into the MH and it was freezing

The thermostat was reading 75 degrees, and since it was set for 70 degrees, everything that could run on 20 amps was running.

Being suspicious about the temp at the thermostat I decided to check it against a good thermometer. I placed a good thermometer on the ledge at the bottom of the thermostat and it read 70 degrees.

No wonder I was burning up during our last weekend camping trip, setting out in the direct sun at 96+ degrees, and the inside temperature was reading 81 degrees. Should have been reading 76 degrees

Is there anyway to calibrate the thermostat?

[smlranger]

I had a similar issue couple of years ago and called RVP to ask if their thermostats could be calibrated. They said no and sent me a new TruAir thermostat.

[MrTransistor]

Hi Ron & Dee,

Not easy, but it can be done. The thermostat uses a diode junction to sense the temperature. It seems to usually be on the high side. This can be corrected with the addition of a high value resistor (100K to 10M ohm).

I have recalibrated the thermostats in the Adventurer, the Journey, and the Horizon with the proper resistor. The problem for most people is that to get it right takes a “decade resistance box”. If you have an electronics buddy with a box, have him connect the decade box across the sensing diode and adjust the box to achieve a calibrated display.

Use the value determined to purchase a ½ Watt resistor that is as close to the value as possible but not less than the value determined. Solder it across the diode. This should get the thermostat calibrated to within ½ degree Fahrenheit. I’m amazed that TruAir did not design the thermostat with a trim pot. installed. They just install all the parts and out the door it goes. I guess they figure as long as the reading is within +or- 6 degrees, that’s close enough!

They have done the same thing with the NTC (Negative Temperature Coefficient) resistors used to detect a frost condition and shut down the basement air compressors. I believe the book says 40 degrees Fahrenheit but the one on the Horizon was shutting down at around 52 degrees. Hard to heat the coach when that happens.

[ichn2go]

On my coaches I have directed a vent towards the thermo so as to have it cut off sooner than normal. This helps maintain a temp that I desire with little effort. And NO, I know it can't been calibrated but TruAir is very liberal about handing out thermostats . Contact them and Good Luck

[wa8yxm]

Question... What Air Conditioner do you have.. Reason for question

I have a Carrier Air-V The modle I have uses a remote control to turn it on and off (Dang battery eater, I mean it really eats' them)

The Temp sensor is on the fixed panel, not in the remote, and though I"ve never had a problem on A/C..when on Furnace, ti tends to read outside temp, not inside,

Calibration is often poor on those things

The carrier can also be put in an "Emergency cool" mode. in this mode it ignores the T-stat, and just runs, You might also call it 'Meat locker" mode cause.. if it runs long enough, you could store meat in that rig.