Trane Guys???

[kanodogg]

I have a question? I am working on a Trane RTU/Gas Unit M#YCD241C4LBCA S#453100541D. I had a service call yesterday where the customer was concerned why his (CFM) Combustion Fan Motor was staying on at all times. I went to check the unit and traced out the wiring schematic. According to the schematic the unit's CFM gets power from a 480 step down transformer with would send 240 volts to my CFM and 120 to the igniter. According to the schematic this motor has power going to it at all times in the low speed and switches over to the high speed when in the heating mode. What is the purpose of this? If I made a wrong assessment can you please explain?

[grayghost]

I do not have a print in front of me so going on memory. If you look at the print the speed taps go back to the combustion board. the relay in the board determines fan speed. The easiest way to explain is to think of the relay as the internal speed taps on a multiple speed motor. That is actually what it does
If you pull the wires off the relay I bet you will find the motor still runs. The combustion motor is most likely bad, internally shorted and that is why it is running. but check the board relay also

[cg2]

Motor is bad. Service bulletin about em, but cant find it online right now. xxxxbucks our cost. Sucks to be a Trane owner.

[airdata870]

I have a question? I am working on a Trane RTU/Gas Unit M#YCD241C4LBCA S#453100541D. I had a service call yesterday where the customer was concerned why his (CFM) Combustion Fan Motor was staying on at all times. I went to check the unit and traced out the wiring schematic. According to the schematic the unit's CFM gets power from a 480 step down transformer with would send 240 volts to my CFM and 120 to the igniter. According to the schematic this motor has power going to it at all times in the low speed and switches over to the high speed when in the heating mode. What is the purpose of this? If I made a wrong assessment can you please explain?

in the call for heat the K5 & K6 relays on the UCP are energized,the n.o.K6 relay close energizing the heat relay coil and power 24VAC to ign module.
when the n.o.heat relay contacts close power is sent to ign tranformer(tns2)powering the 115vac part of the ign module,the n.o. K5 relay closes to start (CFM) in high spd for 60 sec. hope this helps

[kanodogg]

Thank you for your quick responses. I will contact my customer and tell him my new information.:)

[lipsoffurry]

You might pick up the Voyager Black Book. It will assist you in troubleshooting Micro's and Commerical's. While you are in the Parts Center, get the Relatel book too.

[ezone]

cg2 is right. there is a bulletin avail. certain seris has bad motors. I've changed out two this winter. Found #3 today on a ac start up. Getting Trane to admit it is pretty hard though. First one drives you crazy, the motor is energized on call for heat only.