20 Most Recent Honeywell Electronic Programmable Heat/Cool Thermostat - CT3300A100 Heater - Page 4 Questions & Answers

Replace

By the way the battery is a common CR2032 battery and can be swapped out in 2 minutes. Turn off the unit at the mains, 2 screws at the bottom, push in the plastic connectors and the battery can be slid out

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Check the stat for continuity using a VOM. Check connections? Reset and Reprogram system. Lastly call Honeywell.

Sounds like the internal thermostat is stuck causing the unit to think that it is not cold. If you would like to tackle it yourself it is usually a part of the Expansion valve, witch will require opening the system. I suggest a service professional as Freon is hazardous, and being wrong is expensive. It could just be that the rheostat on he control knob is going bad BUT that wouldn't cause Ice to form on the Unit.

here is the wiring from man. f you have trouble figuring out the programing or what terminals to use in thermostat there is an help phone number. Be shure to turn off all power to unit and thermostat, remove batteries from thermostat.

There may be a sudden weather change or heat change that may set it of. Also it might help to double check your settings just in case one of the buttons or dials have been knocked.

The two wires are the control circuit from the heater your running. They go to the thermostat and close when it get below the thermo. setting and start the heater. If you need further help, I’m available over the phone at https://www.6ya.com/expert/craig_3fa289bf857b1a3c