Heater blowing hot & cold

[Duskcrawler]

Cold morning this morning, car completely covered in frost.

Get down the road, temperature guage sitting happily in the middle as normal, but only cold air from the heater, then suddenly it blows warm air for a few mins, then cold again then warm.

Stopped at my dads and the water level in the radiator is fine and full of anti-freeze though I took his car to work as I was scared of driving it.

Any suggestions of a cause and a cure?

 

[siztenboots]

Cold morning this morning, car completely covered in frost.

Get down the road, temperature guage sitting happily in the middle as normal, but only cold air from the heater, then suddenly it blows warm air for a few mins, then cold again then warm.

Stopped at my dads and the water level in the radiator is fine and full of anti-freeze though I took his car to work as I was scared of driving it.

Any suggestions of a cause and a cure?

Air lock somewhere ?

 

[Bill101]

I second the air lock idea, when it's warm check that all the pipes,top and bottom of the radiator and those into and out of the heater are roughly the same temp.

 

[D33]

I had this problem and had to buy a new radiator and I had an air lock.

In your case, I'd imagine it's just an air lock.