Mitsi VRF actuators

[maxcool]

How is the best way of testing if the actuators for the reversing valves are still working fine? (the little green ones)

[Thermatech]

4 way reversing valves are the same on any heat pump system or VRF system & all operate in the same way.

On Mitsubishi Electric VRF systems when 240v ac is supplied to the 4w valve coil then the 4w reversing valve changes over to heat mode.
When 240v ac is turned off to the 4w reversing valve coil then it changes over to cool mode.

Its very easy with multi meter to see if the 240v ac is being sent from the circuit board to the coil.
The coil can be tested for correct resistance also with multi meter.
If its open circuit or closed circuit then it will not operate & if closed circuit will also take out the control circuit fuse on the circuit board.

Try this basic test.

Put the system is test heat at the remote controllers.
when the system has been running for a few mins check to see if the system is heating correctly with correct heating flow of refrigerant.
Then un plug the 4w reversing valve from the circuit board.
The 4w reversing valve should change over to cooling mode instantly.
Then check for correct cooling flow of refrigerant.
Finally replace the 4w reversing valve plug to the circuit board & now again with 240v ac power to the 4w reversing valve coil it should instantly change back to heating mode.

This basic test will prove correct operation of the 4w reversing valve.

[BritCit_Juve]

To test the solenoid without a multimeter put unit into heating (or cooling whichever energises the reversing valve) and pass the metal tip of a screwdriver over the top of the solenoid. if the solenoid is energised then the screwdriver will also be attracted to it.
Also when the plug of an energised reversing valve is pulled off the pcb you should hear a pressure change as the valve changes over
Brit

[paulwild]

two top tips thanks guys