Mondeo heater doesn't like cold weather!

[CGORST]

When I drive over 50 mph in my Y registered (2001) Mondeo, in cold weather, the temperature gauge drops to zero and the heater goes cold. As soon as my speed drops to below 50, the temperature gauge rises and the heater blows hot air again. I don't have problems at any other time of the year and it only happens when the weather is very cold and I am driving fast.

Does anybody have any idea what is going on? I thought it might be the thermostat and temperature sender but the garage say they won't replace them without putting the car on the diagnostics which will cost �85!!

Thanks

[SlackAlice]

Sounds like your Thermostat has given up the 'ghost' and got stuck open. The garage wants a diagnostic because they are too lazy to do the old fashioned checks and its �85 easy money.

[4GS]

My friend had one as well, same year, and his did exactly the same, he went to a scrap yard, got another thermostat and all went well for about a week, then the same thing happened.

[SlackAlice]

If you get a thermostat from the scrapyard then its probably as old as the one your replacing!

Sometimes you have to bite the bullet and buy a new one :)

[Teddio]

Replace the thermostat with a new one. They are cheap and easy to replace.

[Big Bri]

more than likely to be the impeller on the water pump . not ! the thermostat

[CGORST]

Fantastic! Now at least I can pretend to know what I am talking about when I go to the garage!

Thanks for your help everybody.

Clare