Question about Honeywell Electronic Programmable Heat/Cool Thermostat - CT3300A100 Heater
We have a Honeywell Chronotherm III thermostat. The time and the temperature is not showing on the display. I do believe the batteries are working because the display is still showing some of the settings. None of the buttons respond to reset the time. The fan does will blow in the on position. I switched the thermostat with another one in the house, and it appears that the problem is just with this particular unit. Any tips?
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Posted on Jan 02, 2017
I have had the same problem- twice. It was a similar but different problem each time. The -AC means the ac control voltage isnt making it to the thermostat. In my case both times it was a switch in the control circuit that wasn't closing properly. The easiest was the front cover switch. If the front cover is removed from the furnace or has vibrated loose, the switch will open, preventing the furnace from running. The other instance I ran into was a flow switch on the exhaust blower which ensures the there is flow OUT the chimney. The switch wasn't functioning, so the furnace wouldn't start. The blower would come on for a short time, but the burners wouldn't light.
Hope this helps,
Posted on Dec 12, 2008
Go to honeywell.com
Under red welcome sign
Bottom red highlighted box literature/image search
Type in thermostat model number
Click on arrow to right
Then click on the PDF files owners manual / installation instructions
Posted on Oct 11, 2009
The problem is your 24v power source. I am unsure as to why you put "other than power source or batteries". If you did indeed check that your thermostat is receiving 24v, then I would say that you have a bad thermostat. Hope this helps
Posted on Jan 23, 2010
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