Furnace stopped working.

I noticed a burning smell and I traced it back to the area of the thermostat directly above the furnace. The screen was blank on the thermostat and after resetting it came back on however was not operational.
To eliminate the thermostat I replaced it and the same thing, it did not work.

I went in to the crawl space and opened up the furnace - Carrier Weathermaker 8000.

I taped down the cover switch and shortly after the furnace started to cycle on.
The small motor next to the burners started. The burners ignited and stayed on for approx. 1 minute and then everything shut down.

I am not sure that the blower motor started......

Tonight I am going to check the "fan on" and confirm if the blower starts. I don't believe it did yesterday.

I will also check the voltage at the motor to see if the power is getting there.

Any other suggestions, am I concentrating on the right area. I suspect the burning smell may have been the motor failing.

 

I checked and the fan will not come on using switch on thermostat.

I also checked for voltage at the blower motor while the furnace was going through the start cycle. I did not have voltage at the motor .

I suspect now that there is something wrong with the motherboard.

Any suggestions?

 

At the furnace, jumper the R and G terminals. The fan motor should start.

 

Took motherboard out and it is black on the backside of blower motor relay.

 

That does not sound good.

 

My furnace stays on for a few minutes and then the gas comes on. Shortly a minute later every thing shuts itself down again. Sometime this goes on and off leaving the fan run for a little while. I did replace the iginator and cleaned up the metal rode with sand paper,

 

Please don't revive an old thread. That can easily cause co nfusion which can be dangerous.

Start a new thread and repost, is my suggestion.