# Jumping temperature



## Greencheckerman (Jan 21, 2011)

Hi. recently whilst in traffic my temperature guage rose alarmingly and at the same time the heating blower went cold. As I got moving again the temperature went down and the blower returned to normal. There is coolant and I know the fan is working as it came on when I parked the car up. Has anyboby any ideas what might be the cause. many thanks


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## timfitz63 (Aug 10, 2010)

My first thought was to be sure there was sufficient coolant level in the reservoir; if it's below the "MIN" mark, the heater will blow cold air. Sounds like you've checked that, though.

My next thought would be the thermostat sticking or a coolant flow line getting blocked somehow...?


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## Andrew*Debbie (Jul 2, 2004)

Stuck thermostat, faulty water pump, air trapped in cooling system. I'd start in that order.


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## Mister Chow (Jan 1, 2006)

We had a weird overheating issue with our 2006 Cooper S. Still under warranty and they replaced the thermostat, the fan and a sensor of some sort. Don't recall exactly what parts but the problem was that the fan wasn't going on when the car was stopped or crawling in traffic.


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