4TWX8 - Electronic Expansion Valve

Trane Heat Pump: 4TWX8

Re: Electronic Expansion Valve

The 4TWX8 models use an outdoor Electronic Expansion Valve (EEV) for superheat control.

1. EEV Control Board Codes

2. Expansion Valve Test

The EEV Control board has the ability to manually drive the expansion valve open or closed.

► Valve tests are active in any mode of operation.

Close Valve Test

• Touch "Close" pin to "Test" pin on EEV control. (Leaving the pins jumped for more than 10 seconds will clear faults).
• EEV drives closed (5 sec max) and stays closed for 90 seconds.
  • Status LED will be flashing.
  • Suction pressure should drop (may trip LPCO).

Open Valve Test

• Touch "Open" pin to "Test" pin on EEV control.
• EEV drives closed (5 sec max) and stays closed for 30 seconds.
  • Status LED will be flashing.
  • Suction pressure should increase.
  • Superheat should drop.
• Note: If jumper is left on pins, the OPEN VALVE TEST will be cleared after 30 seconds and will not re-initiate (requires a break and make to reinitialize).

Exit Test Mode

• The Open Valve Test or Closed Valve Test can be cancelled by jumping to the opposite mode Test pin. The system will return to normal super heat control.
• Test mode will cancel if:
  • Unit enters a Defrost mode
  • Y1 input is lost