Hey so i have been having a strange problem with my sisters civic. when you turn on the heat, freezing cold air blows out...so i replaced the thermostat and it was working fine for a day..nice hot air.. then all of a sudden the same thing happened..i thought it was a air bubble in the system so i ran it around 4500 with the rad cap off and let the coolant flow out for a while then topped it off. and nothing! its blowing cold air still! i really need some help please! i live in Alberta and its been -29 the last couple days...thanks guys

 

Sure the reservoir is full?

 

yeah i topped it up after i ran the engine and still nothing...

 

Thermostat?

 

have you checked your heater core?



cold weather can either damage or "choke up" the system up fairly easily



.