# A/C not starting up, bad thermostat?



## gringo (Jan 24, 2010)

Hello, I've been having problems with my A/C not kicking on when it should. Heating seems to have the same problem, but not as often. The thermostat does make a click when it attempts to start the A/C but nothing happens. If I play with the switches enough (back and forth to heat or off and to A/C) sometimes it will work, but for less and less lengths of time. The blower works fine if I switch that to on. The thermostat has had issues for a few months now where it has no power unless set just right against the pins that connect it to the wall mounted piece. If it's all the way it gets no power, I have to back it off just the right amount. For this reason I'm thinking it's probably the thermostat causing this problem as well.

The thermostat is model CT3611. It has wires connected to the following terminals-C, R, W2, E, Y/W1 (bridged with jumper), O, and G. 

I'd like to try to verify the thermostat is the problem before replacing it. Is it possible/safe to just connect the R and Y wires directly? That should bypass the thermostat and kick on the unit right? Would I need to attach the fan blower wire too (G?)? How about the C wire, or is that just thermostat power? Anyone know a safe way to verify? Thanks.


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## gregzoll (Dec 25, 2006)

You just stated that you had problems with the thermostat, so why would you doubt it? I would start with the problem (thermostat), and probably solve the problem by just paying $70 for a good Honeywell that is compatible with your air handler and ac.


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## gringo (Jan 24, 2010)

Well I was just trying to be cheap. Having the loose connection was something I could easily live with (and have been) and didn't want to have to replace it if this was an unrelated issue. The existing thermostat isn't very old, though no longer under warranty.

I did just order a new one online. Couldn't find the one I wanted locally. So that brings me back to my question above, would I be able to connect any of the wires directly, bypassing the thermostat, for now until my new thermostat arrives?


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## Marty S. (Oct 31, 2009)

Yes you can but it will run untill you seperate the wires. With all those connections it sounds like a heat pump. In that case twist R,Y,O and G together for cooling.


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## gringo (Jan 24, 2010)

Yes it's a heat pump, thanks for the response!

I'll give that a try if things get too hot while I wait. I understand it will run continuously while set up that way. I just wanted to know if it was a safe thing to try.


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## gringo (Jan 24, 2010)

*replaced thermostat, no cold air*

Ok, so the replacement thermostat (RTH7600D) has arrived. I hooked it up and the AC kicked on when it should have (and no more problems with the thermostat not keeping power). Now its only blowing hot air. Double, triple checked my wiring, only hot air, almost as if the heat were on. Swapped over to heat, neither garage unit or outdoor unit run at all. Disconnected E and W2 wires completely and let AC kick on, again hot air. 

Any ideas? I hate to call in a repairman. This seems like a problem that will cost me a fortune by the hour.


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## AndrewF (Dec 29, 2008)

Check the settings for the reversing valve. Usually O/B...or some T-stats have a setting that you can change.


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## Houston204 (Oct 18, 2009)

170 = 7
190 = 0


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## gringo (Jan 24, 2010)

Thanks Houston!! You saved me a nice repair bill! I have cold air now. Haven't tried heat, but that's the least of my worries in Florida!


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