Heater disassembly? Isolation fault

[Zuikkis]

Hi,

my third Think has a mysterious heater fault. Car works fine if heater is off. Also with heater on, it works maybe 30 minutes or so, and the heater is working fine during that time.

However then the car stops with isolation fault. If I remove the heater cable and connect dummy plug to the PCU, the car drives again. If I measure heater wire to ground with a "megger" (500V insulation tester) I see only 0.5-0.8 Mohm so it is leaking.

However after waiting perhaps 15 minutes and measuring again, resistance is now >550Mohm which is the maximum the meter shows.. And indeed, you can replug the heater to PCU and it works again.

I assume there must be some kind of coolant leak inside? Do you think it's fixable?

[worry]

Hi Zuikkis,
Yes, I believe it is fixable.
See picture below. You can see the electric connectors is open. And the top area is not very good sealed from the coolant. The pipe connector is the problem. You will see.

Remove the pipe-connectors. Then the screws around the perimeter. I have cut/removed the electric leads here, but you will need to guide them out.

When I opened this heater, there was water present around the connectors. Definitely grounding problems there.
 

[Zuikkis]

Thanks! I will take a look..