Heaters on vauxhall blowing cold air. - elisa1
The heaters on our vauxhall carlton are blowing out cold air what could this be?
Heaters on vauxhall blowing cold air. - No Do$h
IMPORTANT! Check your coolant level before you start the car again!

This happened on my Alfa 10 days ago and the cause was a stone coming in through the grill and putting a hole in the rad. The coolant dropped below the level needed to feed the heater matrix. Fortunately this gave me warning before the temperature gauge hit the ceiling and I was able to pull over and let the car cool. So could be a leaking rad, a split hose, a leak in the matrix (unlikely as you would still get some heat and your car would steam up) or a leak where a hose makes a connection.

It may be an airlock, but unless you've had work done on the car recently there's really no reason for an airlock to form.

It could be a blockage in the heater matrix, but again there is little chance of this happening instantly.

Get thee under the bonnet and check your radiator header tank.
Heaters on vauxhall blowing cold air. - Hawesy1982
Or it COULD be the beginnings of a head gasket problem - but hopefully not. Make sure the car is cold before you check the coolant tho, and listen to see if there's any residual pressure in the header tank when you open it. While you're checking the coolant's ok, have a quick look under the oil filler cap, should be nice and oil-coloured, no 'mayonnaise'.

With a bit of luck it'll be one of the problems No Dosh suggested, but then i am excessively paranoid about head gaskets....
Heaters on vauxhall blowing cold air. - Victorbox
Apart from the previous advice on low coolant level (cold air out the vents on my Cavalier was the first warning the water pump seal had gone) you could have a stuck open thermostat. Do you get any reading on the temperature gauge? Is it stuck in the blue sector even after many miles?
Heaters on vauxhall blowing cold air. - elisa1
The temperature gauge is giving a reading. We had a new water pump recently would the seal have been done then? Also we had a new cylinder Head gasket fitted after having a cracked valve replaced in July? The heater has never worked fanntastically its just never been totally cold
Heaters on vauxhall blowing cold air. - Victorbox
Have you had any heat this autumn? If you do as I do and leave the slider for the heat off (set to fully cold) all summer it could be the heater matrix valve is not opening now you require it. Can you hear or feel the mechanism working when you operate the heater control? Somewhere on the engine bay bulkhead will be the two pipes from the engine cooling system to pipe hot water into & out of the heater matrix. Sorry I don't know the Carlton well so a more knowledgeable expert or a Haynes Manual will help you here. If the Carlton is typically Vauxhall the actual heater matrix will be buried deep inside the dashboard. See if the inlet & outlet pipes are both hot. I do however suspect you have an airlock as suggested in another reply. I would be surprised if the heater was poor if working correctly as my cold morsel of a wife always loves Vauxhalls for their very hot heaters! With our Cavalier and Corsa you can grow tomatoes in the car in winter they can get so hot.
Heaters on vauxhall blowing cold air. - Civic8
How long have you noticed it blowing cold?.Since the work was done or was it like it before.The carlton in my experience has always had a poor heater & have never seen a temperature guage on one reach normal usualy just above the blue is as far as it gets.The heater matrix may have a slight airlock in it as they are not easy to clear fully.But that`s just a thought you never know?

 

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