Parking heater magnetic pump failure?

[SwissXC90]

Originally Posted by siapelan

I followed your advice and - bingo! - with a simple bypass of the overtemp cutoff switch the heater works like a charm. The magnetic pump ticking about 2-3 times a second and the heater heating like it is supposed to.

Great!
One day, when you have some free time, you'll want to remove and strip down the heater, clean it, and then clean the contacts on the overtemp switch. Or replace the switch (best option). Volvo won't sell you a new switch, but Webasto might, as Webasto make the heaters, and they are used in a lot of cars.

Originally Posted by siapelan

---- >>>> A follow-up question to be sure I am not doing unnecessary work; I do need to replace it, it is not possible to 'reset' it somehow?

You only need to reset the heater if it logs a fault, refuses to start and shows Parking Heater Service Required.

As your heater has not yet logged such a fault, no reset of fault history is needed.

I don't think the overtemp has a manual override.
you MAY be able to get the switch working again,. you'll have to disassemble and inspect.

Here's a description of a Webasto fuel burning heater. For a motorhome, but the core module and functions will be the same.
https://www.webasto.com/fileadmin/we...r-top-faqs.pdf

Here's an overtemp switch, not the right one for the Volvo, but you can see how simple it is
https://www.butlertechnik.com/webast...-9004227a-p214

Looking in google looks like Webasto just replace the burner as an entire unit.

You could strip and try and fix your overtemp switch, or fit another, or bypass it altogether....