Heat Pumps and Electric Heating - Heat Pump-Fan will not turn off

Hi,

I just installed a new Honeywell CT3611 thermostat for my Lennox heat pump with elec. aux. heat.

The fan does not turn off when the temp. reaches the level called for. I can manually turn it off by turning the thermostat off and back to heat, but the next time it comes on it continues to blow, just blowing cold air after the temp. is reached.

Lennox:
Furnace/Air Handler
MN - CBM29M-21/26-1P SN - 5801K 55147
Compressor MN 12HPB24 - 8P
SN 5801G 16373

I labeled and transferred wires per Manual specs.

I also checked the wiring inside the air handler.

Air handler Old thermostat H - CT3611 Wire color
- - C - - - - - - C - - - - - - - - - C - - - - Blue
- - G - - - - - - G - - - - - - - - - G - - - - Green
W1/W2 - - - - - W2 - - - - - - - - W2 - - - White
W1/W2 - - - - - E - - - - - - - - - E - - - - Black
- - R - - - - - - R - - - - - - - - - R - - - - Red
(Compressor) - - Y1 - - - - - - - - Y - - - - Yellow
(Compressor) - - O - - - - - - - - - O - - - - Orange

I did not pull the cover on the compressor to see if there were wire codes. The compressor seems to be working OK.

The only thing noted on the thermostat is that the heat indicator (flame graphic) is present while the fan continues to run and is not there when I manually turn off the system and turn it back on.

I think this is a thermostat problem. What do you think??

Thanks,

ltfixit

You should be able to do a simple test to figure out if it is the thermostat or a relay sticking inside the AHU. Let the tsta cycle through as normal and when the fan continues to run simply remove the green wire from either the tstat or AHU whichever is easiest to get to. If the blower stops then the tstat was sending 24 volts through the green wire to engage the blower so it is either setup wrong or defective. If the blower continues to run after you have removed the green wire then take your fist and forcibly hit the side of the AHU if it then stops replace the defective fan relay. If there is no relay replace the fan control board. Good to go.

Thank you for your suggestion. I did the test inside the air handler. The thermostat unplugs from the base when accessing the wires and there obviously would be no voltage at the G terminal.

I did as you suggested and also checked the voltage from the G terminal to the C terminal inside the air handler. There was voltage present (aprox 24V). The fan stopped when I disconnected the wire and started again when the wire was reattached to the G terminal in the air handler.

At this point I assume we have a bad thermostat. Is there any way to reset the programming other than the daily and other program functions in the manual?

Some things have a reset spot that reinitializes the factory computer program. I didn't find any thing on the CT3611 thermostat. Maybe I missed something.

If not, I guess I have a piece of recycle junk.

Thanks again,

ltfixit

Thank you for your suggestion. I did the test inside the air handler. The thermostat unplugs from the base when accessing the wires and there obviously would be no voltage at the G terminal.

I did as you suggested and also checked the voltage from the G terminal to the C terminal inside the air handler. There was voltage present (aprox 24V). The fan stopped when I disconnected the wire and started again when the wire was reattached to the G terminal in the air handler.

At this point I assume we have a bad thermostat. Is there any way to reset the programming other than the daily and other program functions in the manual?

Some things have a reset spot that reinitializes the factory computer program. I didn't find any thing on the CT3611 thermostat. Maybe I missed something.

If not, I guess I have a piece of recycle junk.

Thanks again,

ltfixit

I just got through looking at the install instructions of that model. That is a piece of junk, sorry man.
If you bought it from Home Depot or Lowes return it.
Why did you replace your thermostat to begin with?

Hi,

I bought it on E-bay for a few bucks. I like the idea of a set back thermostat and I am limited because I have a heat pump.

The "Emergency" backup is an electric furnace.

What thermostat do you recommend if any for the Heat Pump??

Thanks,

ltfixit