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Honeywell digital thermostat won't turn off ac.

I justmoved in to this house and I have a honeywell digital thermostat. I can't seem to get the thermostat to turn off the ac. Even in the off position for the switch the air is still on. What can I try? I have read that you need to have the temp. set at least 6 ot 7 degrees higher so that it will turn off but I have tried that and it didn't work. I'm getting cold! Need advice.

Posted by tnera on

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The Honeywell CT87 thermostat is a normal round thermostat, not digital and may have a sub-base installed with it that has a two switches on it. One is for Fan (Auto or On)and the other is for Heat, Cool and Off. Make sure the Fan switch is in the Auto position and the other switch is in either the Cool or Off mode. If you continue to get cooling, you have a short in the thermostat wire or a stuck relay in th indoor or outdoor unit. To test this, while the unit is running; remove the round outer ring on the thermostat by pulling it straight off towards you. You will find 3 slotted head screws that hold the thermostat to the sub-base. These screws are located at the 3 o'clock, 7 o'clock and 9 o'clock positions. Turn these screws counterclockwise with a small head screwdriver. They are held in place so should not fall and get lost. With the front of the thermostat removed from the base, the air conditioner should stop running. If the unit continues to run, you will need to have your A/C system inspected by a technician. If in fact your thermostat is digital, look to see how it is mounted to its sub-base and remove it. If the system stops, you may have a bad thermostat or the Fan switch is in the On position. Hopefully this will help.

Posted on Sep 12, 2007

  • Anonymous Sep 27, 2007

    What did you discover? You gave me a poor rating without a solution, what gives?


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Heating won't go off

Honeywell manuals are online for all its thermostats.
Google search your model number.
Model number is on back of thermostat.
Copy following link for Honeywell resources:
Honeywell manuals are detailed, but each pdf file can be word-searched.
More resources:

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7


Our thermostat has "HOLD" on

Hi, Either push the program or resume program button... or on some you need to push the hold button again to take the hold off... Check the manual if all of this does not work... but the t-stat may be fried...

Here is a tip that tells you how to get a manual for most any Honeywell productonline...

Manual Honeywell How to Find Honeywell Manuals


House lights dim when ac comes on since new honeywell thermostat installed. Is this ok?


This is to tell you that the new installed honeywell thermostat as high voltage capacity, it is ok, it is not good enough, though, it as no much effect on your lighting points, but you can get a technician to see if there is a way to adjust the voltage at the thermostat.

Take care.

New thermostat..have heat but not A/C help....

What are you setting the thermostat to when you turn on the AC , if you turn on the AC and the house is warm you will need to turn the AC down to a lower setting before the the AC will start up.

Honeywell CT3600-AC not working

could be froze up if it is turn it off to melt ice clean unit could be low on freon or bad blower motor

Honeywell Digital Thermostat won't click on if temp is below 59

do you live there? if so here are the rules for setting back temperature: do not lower the temperature more than 8 degrees F from the temperature you want it when your there, setting it back for periods of less than eight hours is also somewhat futile. Due to laws of thermo-dynamics the heat required to recover from more extreme setbacks or shorter periods of time exceeds the savings acquired by taking said action. As to your question directly there are no reasons why your thermostat should not function at any setpoint temperature that it is allowed to set to (45 normally being the lowest) if it does not function below 58 degrees it has a failure and should be replaced before it fails completely. Suggest a Robertshaw or Braeburn brand thermostat, Honeywell quality has slipped over the past decade to unacceptable levels. Unless your considering a Hunter in which case buy another Honeywell.

Central heating thermostat

Looks like it was replaced by the CM67 series, try this link for the manual:



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