Good morning and Happy Columbus Day everyone. I must say that anyone's help and feedback will be much appreciated.

Last night the Thermostat (Honeywell Programmable CT8602) gave the low battery light as my wife was looking to drop it a degree before bed so she decided to replace the batteries.

She opened up the thermostat, replaced the batteries and closed it up. (total time: < 4 minutes). After the thermostat lit back up, she adjusted the temperature and nothing happened.

15 minutes later, the temperature in our small 1 bedroom condo was 83 degrees. :( I'm at a total loss for why the AC would stop working.

My ASSumptions and things I've read so far on this board
Need a new thermostat?
Perhaps a short?
An issue with a fuse (I assume that's at the actual unit outside?)


I guess the bright side to look at is that it's not 100 degrees today and it's a holiday so I have the day to diagnose and fix the problem. :)

All in the name of saving some of our hard earned $$$

- Ted

Here is the location of the manual for your stat.

http://customer.honeywell.com/Techlit/pdf/69-0000s/69-1532.pdf

Also has a toll free customer support number.

Seems simple enough, replace the batteries, if it took you longer than 20-30 seconds, then the time and date need to be re-programmed.

Nothing else.like a short should have occurred. You can ry reset all circuit breakers, including any that may be at the outdoor unit, just to be sure.

There may be a small control fuse for the thermostat/control circuit, located at a control board, either at the indoor fan or outdoor condenser uint, but, replacing the batteries should not have blown a fuse.

Hope this helps some.

Thanks for your comment tkrussell. I reprogrammed the time and date last night and just tried resetting the circuit breakers and the AC didn't kick on after setting it down to 60.

Before I go outside, I'm going to give that customer support number a try. :)

- Ted

After speaking with customer care, they say it's a problem with the thermostat delivering power to the A/C system. Their conclusion was drawn based on the fact that when the system was turned off and the fan on, the fan still didn't kick on.

Their solution was to "contact my local heating and cooling contractor". :mad:

What's next on the list to troubleshoot?

- Ted

Need to get a voltage tester and start checking at various lcations, starting at the control transformer, to be sure you have 24 volts feeding the stat/control circuit.

There is usually only the feed hot at the stat,Red, usually, and no common at the stat, if there is usually Blue.

You can disconnect the red at the stat, and jump out to yellow, which should start the outdoor compressor, green starts fan, white starts heat.

Need to locate a control fuse, and check power in and out, to confirm fuse is OK.

Again the fuse is usually at the control transformer, and is usually at the indoor unit. However, there can b a fuse at the outdoor unit also. Difficult to say exactly, as there are so many variables.

Thanks again tkrussell. I'm going to make a trip to HD and pick up a multimeter and voltage detector. I say in an older post that I could get both for less than $25.

I'll get back on the thread after testing it out. Hopefully, this will find the culprit.

- Ted