After duct cleaning my furnace (heat and air) does not work anymore. The thermostat indicates the system is on. Furnace light is on but the fan is not turning. There is that switch that you press when you open the door to the furnace. I guess is a relay swtich. On when door is closed and off when it is open. Anyways, when pressed manually the fan still does not work. Well sometimes it works and other it does not. Does that mean I have a bad relay switch? But when I took it to an electric shop for testing, I was told there is still continuity in the swithch which means it is still working?? Does anyone have similar problem, or could it be that power duct cleaning has caused some wiring to fall loose?

Thanks

T-Top

The switch your talking about is a power kill switch. if you remove the furnace blower door it turns power supply off going to the unit.(they do not go bad very often) How old is your furnace and what brand is it? Did you check to see if you had power coming in to the furnace. try to give us more info if you can.

2bit

Thanks for quick answer, yes that is the power kill switch then, it is a Carrier WeatherMaker 8000, about 7 years old. When I press it , the furnace light comes on but fan only work a few times and there was a clicking sound when I release the switch.

T-Top

If you keep power on the furnace the light should start blinking giving you a code to what is wrong.( one flash pause two flash = code 21) it should say on the door of the unit what is wrong from counting the flashing light.

2bit

I put the panel back on and the power light is on but it is not blinking.

labman

Start a heating cycle. When something that should happen, blower start, doesn't happen, then you will get the code T-Top described. Post back.

2bit

The thing is I cannot start a heating nor a cooling cycle. Turn the fan to auto or on, no fan action. Turn system to cool or heat, hold the temperature to very cold, air cycle did not start, hold temp to very warm, heating cycle did not start but the furnace light is on and steady, the thermostat said the system was on, but nothing was moving??

hvacservicetech_07

Nothing comes on at all when you make the call for heat? not even the burners? I would check low voltage connections at the furnace, to start.

labman

When it calls for heat, you should have 24 volts Ac between the white and common terminals at the furnace. See the sticky at http://www.askmehelpdesk.com/heating...ons-58313.html
for directions on sorting out furnace or thermostat questions.

T-Top

Remove the blower door again and make sure no low voltage wires(thermostat wires) are pulled away from the terminales. If you dont find any thing wrong get a wire and jumper from R to G on the control board with the door switch closed(use your thumb or tape to keep it closed while doing test) If the blower runs at this point you have a bad connection going to your thermostat,and it sounds like to me it would be the R circuit on the control board.