Your Honeywell thermostat tells the heater or air conditioner when to turn on and for how long to run. You can program them for certain temperatures and you can program them for certain times of the day as well. Sometimes your thermostat may not work as you have programmed it. A little bit of Honeywell thermostat troubleshooting can mean the difference between a simple fix and an expensive repair bill.
Furnace Not Giving Heat
Check to make sure that the circuit breaker has not tripped. If it has, you just need to reset it. The components inside the thermostat could also be dirty or the wires could be loose. Remove the cover and clean the contact points. The easiest way to do this is with canned air. You only need to apply a few quick sprays of indirect air to the contact points.
With the cover still removed, check the wires inside to make sure they are all connected. Tighten any loose wire terminal connections. Check for a loose terminal on the low voltage transformer located at the top of the furnace.
If your Honeywell thermostat is equipped with a battery, check the LED display. If it is not working, replace the battery.
Thermostat Does Not Reach Programmed Temperature
Two things could be causing the thermostat not to reach programmed temperature. First, the thermostat may have been installed crooked. If the thermostat is not level, the mercury switch will not give a true reading. Check the levelness of the thermostat and adjust it if necessary. Remove the cover, loosen the screws and reattach at level.
The other possibility is the heat anticipator is not set correctly. The anticipator is a resistor that fine tunes the thermostat to turn off the furnace. Remove the thermostat cover and adjust the heat anticipator. At the centre of the unit, you will see a small disc. It should have the word "longer" on it as well as some calibration marks. If the temperature is not being reached, you will have to move the anticipator away from the "longer" setting. You may need to make several adjustments before you get it correctly calibrated.
Air System Cycles On and Off Too Frequently
If this is happening, your heat anticipator needs to be adjusted. The difference is that you will have to move the anticipator toward the "longer" setting in this case. Usually doing that and cleaning the contact points with compressed air will solve the problem.