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do we have any HVAC techs here?

SELLERSRODSHOP

SELLERSRODSHOP

Well-Known Member
i'm thinking i have a bad thermostat... again. this is the third one so far on this unit in the last few years. right now, the A/C is on. its set at 77 & actually is 75 in the room with the thermostat, but the thermostat is showing that its 79 & keeps the unit running. are these new digital thermostats that short lived? had the same issue in the winter for a time with the heat. had the unit looked at then & everything was fine.
 
The thermostat operates independent of the central air unit so if it is faulty it is so on it's own. Perhaps it is in a bad location (hit by sunlight or in a corner of the room that does not see good air flow, etc.). Otherwise, I would say yes. It has failed. Again.

What type do you have? Perhaps you bought on the cheap and this is the result? The main one in my house is almost twelve years old at this point and still working. I put a more advanced one (multiple scenario settings, etc.) in for the upstairs unit five years or so and it too is still in service.
 
it is probably a cheap one. it was installed by the company that did the unit & is the third replacement (made in china). its in the corner of the kitchen/dining area & not in sunlight. i hung a thermometer next to it this morning & right now, the unit is set on 78 & running, with the thermostat reading 79. the thermometer next to it shows 75. i even made sure the hole in the wall where the wiring enters is sealed good & not wicking heat from between the walls.
 
I'm not a tech, but I think the thermostat needs to be near the center of the house and near the return to be most efficient. HTH!
 
its in the center & over the return, so thats covered. i also notice when i set the temp at 80-81 & the unit shuts off, the thermostat temp that stays on 79 will start dropping until it reaches the temp shown on the other thermometer. during this test, within about 5 min of the unit shutting off, temp shown has dropped to 77 degrees.
 
I'm sure you know, a thermostat is simply a switch that turns on and off based upon it's actual temperature reading in comparison to the set point. The old ones were simply a mercury switch that basically NEVER failed. Welcome to modern technology!

Based on what you are describing you have another bad one. Simple as that.
 
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