Noticed when driving home tonight the fan in my car starts blowing cold air when stopped at lights etc with the heat on full.

When driving along normally the heater is kicking in as it should ie warm but then goes cold again when stopped at lights- only noticed this tonight, seemed fine this morning on the way to work. Its a 2006 astra if that helps- any ideas??

We had a 98 Astra and that was the first sign of the cylinder head gasket going

Hi they suffer from thermostat problems, it comes complete with housing about £120 fitted . Or it could be the water pump if your realy unlucky as that's driven off the cambelt and labour intensive.
The best way to tell is take the small hose off the expansion tank and see if water pumps out
I could take a look if you want

alternator?????????????????????????????????????

Check your water level. If you have a heater box it could be getting engine water when you are driving but not stationary.

water pump or matrix fail heater controls ?

Cheers for the suggestions- had a little look before and the coolant does look a little low well its under the cold marker anyway but I had just driven home. Will have a proper look in the morning as cant see to much in the dark and my torch isnt the best.

I had a split pipe going to the heater matrix which was emptying coolant in minutes about 6 months ago but the symptoms were different so hoping not the same, doesnt seem to be leaking thou...

Dont think it has a belt think its a chain if that helps?

It is the thermostat mate had exactly the same problem with my Zafira eurocarparts were the cheapest and 20 mins to fit.

chain driven, the pump runs off the drive belt and the stat is about £25.00 and a two minute job to change.

forgot to say...

top it up first, bleed it and then see how it goes, they can be a bit of a fussy system sometimes

also check the drain on the radiator is tight, bottom on the drivers side.

take it yours hasn't got the water temp gauge? if so watch out for them as the coolant level sender can be a pain in the backside, had one the other week that worked in a different time zone

Ok- bit more information........................

Topped up the coolant this morning as was quite low but still some in the tank, it needed quite a lot to fill up to cool marker about 1.5 litres. Just driven about 5 miles and come back checked coolant and its back to roughly where it was originally.

Not sure if this is normal or not but seems to have used a lot of coolant for a very short journey will leave the car outside and go and check in an hour or so.

It is no longer blowing out cold air though! Have checked and no sign of leaks, damaged pipes etc should I be worried?

No theres no temp on the dash in this car....

Definately on tight and not cross theaded etc.

Have you priced a stat up or just gone off hear say the last one I did was £70 to buy
Send me your reg and I will get a more accurate price

The thermostat is most probably stuck open a common fault on vauxhall cars which is why there is no water in the header tank.

Top it up again and don't forget to add anti freeze. Just sounds like it had run low unless you have a leak.

last one i bought was around £25.00 with the housing.

I'm blind here as to what engine it is I'm only going off experience, there are several different types
I hope all turns out well for you

Thanks for your help everyone I think this is now sorted (for now). Filled up with coolant again yesterday and topped the oil up and the coolants still in the tank so happy days.

Ive got a feeling this is something to do with thermostat anyway will see what develops over next few days