4WCX - Blower Not Operating

Trane Package Unit: 4WCX

Re: Indoor Blower Not Running

The 4WCX package unit uses a standard, PSC motor. The motor is controlled by a Fan-Delay Relay (FDR).

CHECKOUT:

1. Check High Voltage Power

• Check for 230VAC inlet power across L1 and L2 of the compressor contactor.
  • No Power --> Check Disconnect and Breakers
    • Check for a "Short-to-Ground" before checking breaker!

2. Check Low Voltage Power

• Ensure the thermostat is calling for either heating or cooling.
• At the low voltage wiring, check for 24VAC between "Red" and "Blue".
  • No Power = Bad Transformer or Blown Fuse
• Check for 24VAC between "Green" and "Blue".
  • No Power = No Call for Fan --> Recheck Stat

3. Check Fan Relay

• Low Voltage
• At the FDR, check for 24VAC between the "Red" wire on terminal "A" and the "Blue" wire on terminal "B".
  • No Power on "A" = No 24V Power --> Check Fuse & Transformer.
• At the FDR, check for 24VAC between the "Green" wire on terminal "T" and the "Blue" wire on terminal "B".
  • Power on "G" + No Power at "T" = Bad Wiring
• Inlet Line Power
• At the FDR, check for 230VAC between the "Red" wire on terminal 1 and the "Black" wire on the Contactor inlet power.
• Outlet Line Power
• At the FDR, check for 230VAC between the "Red" wire on terminal 3 and the "Black" wire on the Contactor inlet power.
  • Low Voltage Present + No Outlet Power = Bad FDR

4. Check Capacitor

• Disconnect power to the unit and test the blower motor capacitor.
  • Less that 80% rated capacity = Bad Capacitor
  • Good Capacitor + Power to Motor + No Operation = Bad Blower Motor