Help! No heat, ambient temp display reads --


New member
The temp display on our has been wonky for about a year now, in the past it has read a temperature that may or may not have been correct, or typically it has read "--". The HVAC system will run the A/C or heat when it feels like it. With winter coming up and the wife needing heat, I replaced the temp sensor in the mirror with a new Volvo part from FCP, based on information I read on this and other forums. After the replacement, the display reads "--", and will not show a temperature. Figuring I received a defective part, I ordered a new one and replaced it this evening. No dice. It still reads "--" and I have no heat. This week is the coldest of the year so far and I'm looking for options. I've flushed the heater core and it flows fine, and it has newer coolant at the appropriate level. I'm convinced it's electrical, but I don't know where to go from here.

Any help would be GREATLY appreciated!


Well-known member
Ours was replaced under warranty in the summer months twice! Each time, the software had to be updated by the service dept at the dealership.
Sounds like you need the software updated to recognize the new sensor.