Trane Heat Pump: 4TWB3
Re: Outdoor Unit Not Running
- The thermostat is calling for either HEATING or COOLING.
- The Indoor fan is operating.
- Neither the Outdoor Fan or Compressor are operating.
Qty |
Possible Causes: |
|
Bad Dual Capacitor |
|
Tripped Breaker |
1 |
Low Pressure Switch |
|
Hi Pressure Switch |
|
Bad Contactor |
|
Bad Disconnect |
|
No Low Voltage Signal |
CHECKOUT
1. Check High Voltage
- Open the outdoor unit control cabinet.
- Check for 200 - 240VAC on the inlet side of the compressor contactor.
- No or Low Voltage ⇒ Check Power at Disconnect & Breaker Panel
- Check to see if the compressor contactor is pulled-in.
- Check for 200 - 240VAC on the leaving side of the compressor contactor.
2. Check Capacitor
- Break power to the outdoor unit by pulling the service disconnect or turning off the breaker.
- Remove wires from "C" and "HERM" of the capacitor.
- Move Meter leads to COM and MFD.
- Set Meter to 200 MFD.
- Place one lead on capacitor "C" and the other on capacitor terminal "HERM"
- Confirm MFD reading with capacitor rating.
- Less than 80% of rating = Bad Capacitor
- SWITCH METER LEADS BACK TO COM AND V BEFORE PROCEEDING!
3. Check Low Voltage
- At the outdoor unit low voltage connections, check for 24VAC between "Red" and "Blue".
- No Power = Blown Low Voltage Fuse or No Air Handler Power
- Check for 24VAC between "Yellow" and "Blue".
- No Power = No call from the thermostat ⇒ Recheck thermostat and look for a condensate overflow switch at the air handler.
- Check for 24VAC at the compressor contactor coil "YL/RD" and "Blue".
- No Power at Contactor + Power on "Y" = Open Safety → Step 4. Check Safeties
- Power at Contactor + Contactor Not Pulled-In = Bad Contactor
4. Check Safeties
- At the defrost board plug, check for inlet power between "Yellow" and "Blue".
- No Power = No call on "Y" or Broken Wire
- At the defrost board, check for 24VAC between "YL/BK" and "Blue".
- No Power = Anti-Short-Cycle Delay or Bad Defrost Board
- Power Present ⇒ Continue
- At the wire-nut splice, check for 24VAC between "YL/RD ⇔ RD" and "Blue".
- No Power = Open Low Pressure Switch
- Power Present ⇒ Continue
- At the compressor contactor, check for 24VAC between "YL/RD" and "Blue".
- No Power = Open Hi Pressure Switch
- Power Present + Contactor Not Pulled-In = Bad Contactor