Solenoid Valve Troubleshooting for Split Systems

Use this troubleshooting guide for split systems if the evaporator unit shuts off but the compressor stays running continuously.

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ISSUE:

Evaporator unit shuts off, but the compressor stays running continuously.

 

DIAGNOSTIC STEPS/QUESTIONS:

First thing to check is the direction on the solenoid valve. Visually inspect the solenoid valve for an arrow on the body. The arrow should be pointing in the refrigerant flow direction of the TXV. If the arrow direction is not pointing toward the TXV, then the valve is installed backwards and needs to be corrected. If the arrow is in the correct direction, proceed to the following steps.

1. Disconnect power to the evaporator unit. This should cause the solenoid valve to close.
2. Go outside and check to see if compressor is running.
   1. What are the pressures on your gauges?
      1. The suction pressure is supposed to be dropping steadily until the compressor shuts off.
   2. What does the Emerson controller display show for the suction pressure?
      1. The Emerson displays the suction pressure on the screen, this is supposed to be dropping steadily until the compressor shuts off.
   3. What are the cut-in and cutout pressures settings currently on the controller?
   4. If the cut-in and cutout pressures are not at factory settings, put them back to factory settings (cut-in 25psi, cutout 15psi).
3. If the compressor stays running for longer than 2 minutes after the evaporator was shut off, then the solenoid valve is possibly stuck open, or there is an internal issue with the compressor.
4. Front seat the suction service valve on the condensing unit.
   1. This will close off the suction line and cause the refrigerant to be pumped into the high side of the system.
   2. This should cause the suction pressure to drop to the cutout point.
   3. Once the cutout point is reached, the compressor and condenser fan should shut off.
5. Once the compressor has shut off, watch closely to see if the compressor short cycles.
   1. If short cycling is occurring, then there is possible damage to the internal valves of the compressor, which is causing refrigerant to leak back from the high side, into the low side.
   2. The compressor can be condemned at this point because we have isolated the compressor from the suction line and the continuous running issue is still present.

If the compressor is holding steady with the suction valve front-seated and is not short cycling, continue with troubleshooting for solenoid.

Note: Evaporator power is still disconnected at this point and the Evaporator unit is off.

6. Once you have confirmed the condensing unit is holding steady and not short cycling with the suction service valve front-seated, you will open the suction service valve.
   1. If the compressor turns on and runs continuously, or short cycles often, then this is a sign of a faulty solenoid valve.
   2. The evaporator unit is still off, and the solenoid valve should be closed and not allowing any refrigerant to flow through.
7. At this point, the cause of the issue is the solenoid valve not closing. The component should be replaced.