Heater fan issues

[Mark A]

I was asked to look at a friend Roadster which has an intermittent heater fan issue this weekend.

I checked and replaced the control unit
Pulled the fan motor out and connected to a 12v supply works fine
I can hear the solenoid clicking when switching on the fan controller 
The current from the solenoid seems to be lower than I was expecting, so changing the solenoid behind the glove box
All the wiring looks intact and no other systems appear affected

I'm going to have another look later this week, I was think of bypassing the solenoid with a patch cable, any other suggestions or experiences of faulty heater fans?
 

[Alex Knight]

What is the actual issue? It's not clear.

[Mark A]

Sorry, the fan does not run or will work for a little time then stop.

[Alex Knight]

Sorry, the fan does not run or will work for a little time then stop.

Have you ruled out the switch?

Easy to swap over a known working unit.

[Mark A]

Yep changed the hvac unit over and no different

[Alex Knight]

Think you'll need to test the circuit with a multimeter.