I find that the aux cabin heater doesn't go off, however if I turn the main heater control off and on again then it stays off.

This has been the same throughout the summer so I don't think it's temp related.

Also at least half the time I turn the engine off there is a constant buzzer, I can't pinpoint the location but it seems louder inside the car.
This lasts for about three to four minutes then stops.

Could these two thing be related.

Thanks

John

 

how far up does the needle on your temperature gauge go? If it's not getting to half way then the thermostat is jammed open and thus the aux heater is running as it doesn't think the engine is up to temperature

Regards
Ricahrd

 

Thanks for the logic

The needle sits about 3mm under the horizontal, should I change the thermostst.

Sounds like a cheap fix

john

 

With 3 mm under the "halfway" I dont think your thermostat is broken.. Look for a broken thermostat on my thread.. And feel lucky, because on a CRD that is NOT a cheap fix, unless you follow Leedman's instructions
https://www.chryslerforum.com/forum/...-broken-23454/

 

normally a stuck open thermostat will make the needle sit at about 1/4. It should sit bang on halfway, which yours sounds very close to. Can you get the live data to see what the ECU thinks the engine temp is?

Regards
Richard