Hi,

Yesterday I got in my MY99 and wacked the heater on, as we all probably did. After about 3 minutes the heat started to come through. Then about 5 minutes into my journey the heater started blowing cold air into the car! after about a minute the air started to warm up, but never got to really hot as it normally does. Then again after a few minutes it went cold again.

This morning exactly the same the heat built up as the car ran for longer, then all of a sudden the cold came, and then the hot!

Is this a faulty heater? Or anything else I can try?

Thanks, PaulG.

 

i assume you checked the cooling system has sufficent water in it!!!!
heater taps???

 

Thanks for (prompt) reply! I thought the cooling system was for engine temps? The Engine temp seems fine, gets to about half way and stops, and what are heater taps? can't find anything about "heater taps" on the web.

 

your cooling system is for the engine but you also have a pipe running behind your dash into a heater matrix and then back into your engine bay.

your fan for your heaters in the car blows air through your matrix which when the engine and water is warm it blows hot air into your car.

you may have sufficient water to keep engine temp down but its air locked the heater matrix.

check water and top up if required, keep cap off and run engine squeeze all the pipes and top up as required. that should get all the air out and make your heaters stay warm

 

Wouldnt it just be the stat opening ?

 

doesn't explain hot cold warm cold.

water still flows round the matrix and engine until its warm enough for the thermostat 2 open and allow coolant round the radiator.

 

Thanks all, I topped the tank up and the heater no longer blows cold! I will keep an eye on it.

Thanks again!

 

There wasn't any odd waxy looking stuff in the water filler pipe, was there? Checked yr oil lately? It's not frothy is it?

Mine was, and it's the head gaskets,

Mine refused to blow hot too, until I topped it up.