Hello- I have two Carrier WeatherMakers (58SX)

Furnace number one: Inducer motor won't start

Furnace number two:
Just started acting up today. Last year we had a service company replace just about everything in this unit with poor results and a heck of a lot of $$$$. As a last resort I ran new thermostat wire and it has been fine up until today. The furnace works but I had to flip the SSR switch twice to get it to restart when the thermostat re calls for-heat.

Furnace number !:
If nothing happens when you turn on the thermostat it could be many different things.
First make sure you have power to the unit.
Next make sure that the door switch is making a connection when it it closed.
Next make sure the fuse on the board is not blown, if so replace it with a 3 or 5 amp fuse.
Next when thermostat is calling for heat make sure you have power to the inducer motor. About the only way to do this is with a volt meter ( A real meter and not one that just makes a light glow).
If you don't have power at the motor and after you have determined that you have power to the furnace board by checking the voltage at terminal L1and L2. If you have powere use the meter to check Primary L1 and primary L2. If you have power then connect the R terminal to the W terminal on the circuit board with a jumper wire. If you get something to start that means something is wrong with the thermostat or the wires going to it.

Furnace 2: I am not sure what the SSR switch is, so tell me what it is and also is the unit still working right now. If not you can use some of the test above to find the problem.

Thank you for your response. Everything checks out on your list up to the fuse. I will check voltage the voltage. Is there a chance it could be the ignitor?

Furnace 2: I was referring to the switch, (looks like a wall switch) outside of the unit

Thnak you again for your time!

If the inducer motor will not run it is not the ignitor, the ignitor will not try to glow until the inducer has run for about 30 seconds.

On furnace one what happened when you jumpered the R terminal and the W terminal on the low voltage section of the board.

Hello-
Furnace number one.:
I have power to the board. I jumped between R and W with no results. I would like to put a meter on the Inducer, but it's power connector slides directly onto a small transistor board. Also something to note, when I turn the power on the black box on the top right that with the orange wire that goes to the ignitor clicks. Also, if I turn the power on and off sevral times, the furnace blower can be tricked into running.

Furnace number two had a poor connection and is running fine now.

If the inducer won't run, the "transistor board" (actually referred to as the inducer control board) may be the problem. Try this: dismount the pressure switch from the inducer control housing, set the thermostat for heat operation, and tap the relay on the inducer control housing with the butt of a screwdriver. If the inducer starts/runs, the relay contacts are burned/oxidized. Replacement of the inducer control will correct this problem. If kit #313680-751 is used, be sure to follow ALL the instructions included for adding the additional circuit to the control. Simply popping the board in will not solve the problem.

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Thank you for the great pictures. I gave the relay some good taps- no luck, could the pressure switch be the culprit?

Will I be risking any damage to the control unit of unit two if I use it on Furnace one?

It's not likely you would risk any damage, but it may not be productive. If you look closely at the inducer control board, you may notice that the cover can be removed from the relay. A pocket screwdriver will usually accomplish this. If the inside of the cover shows evidence of burning, the relay may be the problem. Try operating using the power supply switch, & with the thermostat set to demand heat. If the relay is engaging but the inducer does not run, CAREFULLY nudge the relay bridge with a screwdriver. If arcing at the contacts and/or motor operation is observed, you've identified the culprit. In a pinch, the contacts can be cleaned with a sliver of sandpaper, until the control can be replaced.

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Will do. And once again- thank you for your time- I really appreciate all the info!

I could not get the cover off the relay without amaging the board. So I switched controller units. Still no preheat/inducer action.

Did you try installing the inducer control from the non-functional unit on the functional unit? If you have a voltmeter, you can check for voltage output by removing the inducer control from the housing, and re-connecting the plugs to the control board. Touch the meter probes to the contacts where the inducer motor plugs in. If you measure approximately 115-125 volts but the motor doesn't run, the motor has failed. If no voltage is present, the problem may be in the pilot switch or fusible link.