Danfoss HSA3 not functioning properly

I have a danfoss hsa3 with 3 way valve. In the last month it has stopped functioning correctly.

Now when CH is called only the motor winds, clicks the midway micro switch briefly then clicks back slightly past the switch turning it off again.

If HW and CH are called then it’s both work.

HW works fine on its own (default position I know).

I have changed the HSA3 for a new one but get the same problem.

I have looked at all the wiring in the box and Connected to my Nest control unit and it all appears fine.

Have I just been unlucky and bought a faulty motor to replace the other!?

Martin lear said:

I have changed the HSA3 for a new one but get the same problem.

Click to expand...

The whole valve or the actuator head only?

The actuator only. Head is moving freely and actuator still does it when off the valve.

when the actuator is moving from HW only to CH only, the short on off that you describe is supposed to happen it is not a fault

It’s not the problem. The problem is calling CH only. It passes the microswitch you hear the click and the pump start for a second or two then it moves back approx 2-3mm passed the microswitch turning the pump off.
It most definitely isn’t working correctly.