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

Green LED	Description
On Continuous	Heat Mode - Standby
2 Sec On	Cool Mode - Standby
Fast Flashing	Control is driving valve
1 Flash, 2 Sec Off	1st Stage Heat
2 Flash, 2 Sec Off	2nd Stage Heat
1 Flash, 4 Sec Off	1st Stage Cool
2 Flash, 4 Sec Off	2nd Stage Cool
Red LED	Description
Off	Normal
1 Flash	Open or Shorted EEV Coil (Replace Coil)
2 Flashes	Internal Failure (Replace EEV Control)
3 Flashes	Pressure Out of Range (Replace transducer) 1
4 Flashes	Temperature Sensor Out of Range (Replace sensor) 1
5 Flashes	Shorted Coil (Replace Coil) 2
6 Flashes	Valve Not Responding
7 Flashes	System Not Performing Properly
8 Flashes	Compressor Not Pumping 3
9 Flashes	Low Superheat in Cooling
1 = Valve will close and LPCO will trip. 2 = Power supply will shut down to protect board 3 = Monitor superheat and pressures

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