Heater Problems

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Hey all.

Im having some troubles with my heater.

Today i started my GTI up and let it get warm (half way up temp gauge) and i was only getting warm air (not very warm i may ad) from the vents that blow air onto the screen.

Ive checked all the pipes and hoses and there all nice and hot but why isnt my car getting warm inside? When i had my cam belt replaced i asked them to do see about the heater, he squeezed the hose and it was hot again, but its not working again now.

What do you have to do? 

[action al]

Matrix has gone.
If your car has been recalled, you will have the heater by-pass valves fitted. these loop hot water back round to the engine, i.e. not through the matrix, if the pressure builds up in the heater matrix, due to a blockage, so as not to break the matrix and you getting steam coming out your vents!
Just replaced mine yesterday, pig of a job to to! took about 6 hours.
If you are going to do it yourself then look at the instructions on the clubgti forum

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I dont get any steam coming through the vents.

[Deefadog]

There could be an air block, i think the best way for this is to run your engine hot with the coolent resevoir car off untill it starts to boil over, this should get the air out.? btw have you heater open on hot when doing this

Double check this before you with someone else here in case i remember it wrong!

[Gambit]

aye just try bleeding the system as said above, then  change the bypass valves if it still aint fixed

if the heater matrix had gone then all the coolant would be lying in your footwell

[rubjonny]

Bypass valves are now obsolete from VW, I would remove them completely and replace with straight through pipe to see if that clears the problem, if so you know your valves were shafted.  If not either the matrix is blocked (have you ever put radweld in your coolant?) or possibly the water pump is on the way out!

[action al]

I wouldn't recomend bypassing the bypass valves. I did this and thought I had fixed it! I had heat again but then about a week later I had a funny smell which got worse then I started steaming up. The bypass valves are there for a reason: to stop the matrix blowing up, and they were working fine. If there is no heat inside the car it's more than likely the matrix at fault not the valves!
Incidently: The hot water runs through the matrix continously, i.e. there are no controling valves in the line to the matrix. The heat is controlled by the movement of paddles in the air box, so it can't be a sticky valve unless the by-pass valves are stuck open, but this is normally due to a fault with the matrix!

[ridgers]

You cant remove the bypass valve on a mark 2 without replacing the heater matrix with a MK3 item.

VW had to put the bypass valve in as a recall because the heater matrix was discovered to be weak and was popping/leaking.

Obivously it was more cost effective for VW to fit a valve then it was to have a customers car in and rip out the dash to fit a new matrix.

MK3's dont have a bypass valve as they got the matrix strong enough and you need to fit a decent make one like either a proper VW one or a valeo one to your MK2 before doing away with your bypass valve.