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airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 7776
Experience:  Furnace, A/C and heat pump specialist.
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I just replaced both Honeywell PRO TH3000 Series thermostats

Customer Question

I just replaced both Honeywell PRO TH3000 Series thermostats with Honeywell RTH2510 Series. One thermostat is functioning properly. The other one did not. I put the PRO TH3000 series back on. It now does not trigger the AC.
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.
Hello. My name is ***** ***** I'll do my best to help. Let's get started and see what we can do.Do you have two systems or just one system with 2 thermostats?
Customer: replied 1 year ago.
2 zones. One zone is a Goodman and is operating fine. The other zone is a newer Carrier and is the one that is not being triggered by the thermostat.
Expert:  airheatman replied 1 year ago.
OK if you have 2 zones but only one system, I will open to other experts as I am not that familiar with the zone control.
Customer: replied 1 year ago.
I am not sure what you mean by one system. I have two furnaces in the house and two a/c units/fans outside. I think they are two different systems. Two different circuit breakers.
Expert:  airheatman replied 1 year ago.
OK if you have 2 thermostats and t systems, this is good.(not a zoned system).Did you turn off power before removing old thermostat? If not we may have a blown fuse (auto type) in furnace if wires touched.
Customer: replied 1 year ago.
Yes. Swtiched off both circuit breakers and replaced both thermostats. Then switched on both circuit breakers.
Customer: replied 1 year ago.
Then, switched both breakers back off to put the original Honeywell back on. Then, switched on both breakers.
Expert:  airheatman replied 1 year ago.
OK we may have a wire in wrong place on new stat. Lest go to furnace first and see if there is a small fuse on furnace control board in blower compartment and check to see if it is blown,,We will go from there.
Customer: replied 1 year ago.
What tools will I need? Tools are in the garage. Furnace is in the attic. And, I need to get an 8' ladder out, too.
Expert:  airheatman replied 1 year ago.
If gas furnace. usually won't need tools to check fuse as panels slide off. Take a 5/16 nut driver just in case yours hs screws. Control board is going to be in blower compartment.
Customer: replied 1 year ago.
I am up here. The front appears to have a knob, but when I turn it, the front plate does not come off.
Customer: replied 1 year ago.
Disregard. Just came loose. What am I looking for?
Expert:  airheatman replied 1 year ago.
Mounted on blower housing should be a control board.On that board look for a 3 or 5 amp auto fuse.Remove fuse and see if it is burned.
Customer: replied 1 year ago.
I do not see anything resembling an auto fuse anywhere.
Expert:  airheatman replied 1 year ago.
Can you give me model on furnace? It will be on a label i burner compartment
Customer: replied 1 year ago.
58cva070-12
Expert:  airheatman replied 1 year ago.
Check link below and tell me if this is your board.If so fuse is a purple 3 amp.
http://i.imgur.com/pKP74Wg.png
Customer: replied 1 year ago.
I do not see that at all. I think I will have to call someone out. Thank you for your help.
Expert:  airheatman replied 1 year ago.
I understand. THis is going to be mounted to blower housing.May have a cover over it to protect from dust.
Let me ask you a question. Do you remember what wires went where on old thermostat and what you connected where on new thermostat?
Expert:  airheatman replied 1 year ago.
Did your old thermostat have a wire to C terminal and if so, what did you do with it on new thermostat?
Customer: replied 1 year ago.
Yes to the C; it was a blue wire. No C on the new thermostat. Wrapped the end in electrician's tape, per the installation instructions and did not attempt to hook it up. Upon reinstall of the old thermostat, put it back in the slot it came from.
Expert:  airheatman replied 1 year ago.
OK if you wish to continue, let me know.Below is a link showing the location of board.Fuse we want to check is plugged into the board as shown in previous post.
http://i.imgur.com/J2rykSP.png