The car runs fine untill i turn on the heater its fine for a bit then blows cold and the car starts to over heat any ideas?

i had the same problem.. flush the radiator. and put in more antifreeze and water. make sure it is close to 50/50. also check your radiator cap to see if it is holing pressure.

if that not it take it to see if the temp. gauge is even right i have a friend with a MX6 and his car shows the temp as being over the red line but there is nothing wrong exept the thermostat is broken

U need a new rad, a your leaking coolant and that's why your thermostat all off a sudden tells the car your overheating b/c there's not coolant getting to it, just steam. For the heater to properly work your have to have the coolant system to work. A new rad is a cheap easy fix, and you'll be able to she all the problems it fixes after. On mine my alt. was making a wierd soung 2 until i got a new rad.

Sounds like a bad thermostat. not the one that tells your engine temp but the one that controls the flow of coolant. very easy and cheap fix.