random heater problem + overheating

[acko]

Hy Guys,

My interior heater blower unit has been broken for a while now, resistors blown so only works on top speed, but my heat selector has always worked fine selecting hot and cold. Now it seems to have heat to it only when it feels like it.

When I am driving I will have the heat set to hot, and it will be blowing nice and hot. At this point the engine heat is about half way on the indicator at standard temp. Then all of a sudden the heater will stop blowing hot air and turn to cold and the engine temperature will increase, sometimes until the warning light comes on. then after five or so minutes the heater will start blowing hot air again and the temperature will decrease to normal. This cycle continues all the time. I was driving from nottingham up to york and it did this all the time for the whole journey! very strange

If anybody has any ideas i would greatly apprieciate it as I need heat back in my interior! Also if anybody has a circular resistor blower unit for sale I would be intrested.

Cheers peeps

Acko

[gibby]

Isn't heater blowing cold air when set to warm a sign of a blown head gasket  Seems strange that it blows hot then cold though  Maybe gasket is on its way out, might be an idea to get a pressure test done  Mind if it is head gasket the engine temp wouldn't come down  Hmmm, sorry, not being much help here am I 

[acko]

Could be worth checking out. I've chacked the oil filler cap and there is no sign of any white gunk so theres no water mixing with the oil. I didn't know that the heater blowing cold was a sign of a blown head gasket though so thats good to know anyway, cheers

[acko]

Oh, its a 1.6 driver if that makes any difference

[gibby]

I'm going by when the missus had a *ahem *cough fiat bravo, every time the heater blew cold when on hot it meant that the head gasget had blown, three times that happened on the same car  By the way, I was told that the head gasket can blow but you don't necessarily get a creamy deposit in the oil  To be honest it doesn't seem like the head gasket but maybe someone else knows more. 

[...joe]

you could have some sh!t in your coolant that is blocking the flow and so the water can't circulate properly, thus stopping the warm air and overheating. not at all sure about this just trying to think of a simple answer!

[acko]

hey up guys,

Just had a gander on matey matey and someone theres got a similar problem. People were suggesting the heater bypas valves as a possible cause. Are these hard/expensive to replace?

Acko

[rubjonny]

Hardest part about replacing the bypass valvs is actually finding them these days, VW have discontinued them.  http://www.gsfcarparts.com may have some but you'll probably have to ring up.

This wouldn't cause the car to overheat though, and the fact that the heaters DO get hot means it probably isn't the bypass valves at all.

It sounds like to me you have an airlock in the system or something is blocking up the coolant flow. 

Actually it sounds like the waterpump isn't working properly, either the impeller has dropped off/is spinning on the shaft or perhaps the altinator belt is slipping!  Replace the belt first then if this don't help replace the impeller on the waterpump.