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BillyHvac
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22110
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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Replacing Honeywell TH5220D1003 thermostat with a Honeywell

Customer Question

replacing Honeywell TH5220D1003 thermostat with a Honeywell RTH6350 D 1000. The old one had 6 wires the new one only 5. The 6th one on the old unit was blue and went to terminal C. The new unit has no terminal C, what do I do with that blue wire?
Submitted: 1 year ago.
Category: HVAC
Expert:  BillyHvac replied 1 year ago.
Hello,
if the new thermostat has no C connection...tape off the wire and tuck away. But make sure to tape it.
Billy
Customer: replied 1 year ago.
I tried that, it didn't work. I understand that the "C" terminal is the compressor.
Expert:  BillyHvac replied 1 year ago.
no, the c wire is common for when no batteries are used.
Was furnace power off when you changed stat?
Customer: replied 1 year ago.
Expert:  BillyHvac replied 1 year ago.
if you take the red wire...and touch to the green wire...does the blower start?
Customer: replied 1 year ago.
The blower is running, the compressor tries to start then cuts off.
Expert:  BillyHvac replied 1 year ago.
did this happen before stat change
Customer: replied 1 year ago.
It happened a few weeks ago but I removed the thermostat from he wall plate, removed the back-up batteries, waited a few minutes and replaced the batteries and snapped the thermostat back into place. The everything ran fine until today.
Expert:  BillyHvac replied 1 year ago.
the thermostat is only 24v circuit. The compressor is 240 circuit. So if the compressor is trying to start and stops it is not the thermostat.
Now....does the fan in top run or does it shut down also?
Customer: replied 1 year ago.
It shuts down also. Doesn't the thermostat tell the compressor when to start and stop? Also, the heat pump side works fine.
Expert:  BillyHvac replied 1 year ago.
I was going by "compressor tries to start"....but if the fan soeant either you mean the entire condenser. The compressor is in the bottom of the condenser.
If you touch red to yellow...does condenser start?
Customer: replied 1 year ago.
Both the compressor and the fan on top try to start. The vent circulation blower runs fine.
Expert:  BillyHvac replied 1 year ago.
Ok...r to y bypasses the thermostat totally and sends a signal for the condenser to kick on.
How long does the unit run before it shuts down?
Customer: replied 1 year ago.
1-3 seconds
Didn't work, the compressor and fan didn't come on.
Expert:  BillyHvac replied 1 year ago.
Ok,
so the issue is not thermostat related as we took the stat out of the loop.
Now it becomes a troubleshoot game for the 24v. Do you have a meter?

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