Heater only on HOT????

Interior heater guys will not switch to cold. The slider in the dash, the cable works fine and moves the flap on the pipe in the engine bay!
Any Ideas guys before I start ripping the thing to pieces!!!

guess here, maybe the control unit on the pipe (aka the flap   ) is not working internally  :dontknow:

I'd have checked everything you've just suggested

Sounds to me like the valve is not closing internally. If its an original one, its probably well past its replacement date so change it now before it decides to leak and you get stranded with no coolant  :wink: .

Replacements are less than a tenner from GSF / ECP and its an easy swap to do. I would also replace the small bit of metal tube in the coolant hose as it will be very corroded by now if its original. VW do a replacement nylon version that is cheap and easy to fit - highly recommended.

If your system hasn't been drained for a while then I'd do it and flush it through before refilling with the correct mix of the pink stuff (G12?). This will really help the engine run cooler - I noticed a big difference after doing mine.

Cheers,

Chris

I'm new to all this Chris. whats G12 and where do I get it and what mixture. As to the rest i'll be zipping up to ECP and VW today mate, cheers!!!

G12 is the coolant antifreeze concentrate - at least I think its G12 (someone help me out here - or is it G13? Its bright pink anyway), and ECP definitely sell it as thats where I got mine from. Its important to flush out the system with clean water until it runs clean though after draining it. You also need to mix it with de-ionised water (ECP also had this), and I think the mix is about 50-50 - check the G12 bottle for confirmation though.

Rinsing the system through will make sure that all the traces of the old coolant are removed. You need to leave the heater valve on hot too to make sure that the heater matrix and associated tubes get flushed out.

I think there was a thread started by TallPete that I contributed to about 18 months ago with the info on part numbers for the VW nylon connector and some pics of the ECP valve and where it fits.

If draining the coolant system it might also be a good time to check the rubber hoses and metal clips going to the heater matrix from the engine compartment. If they look a bit perished now would be a good time to replace those too.

Take your time and do things methodically and you won't go far wrong.

Just ask if you need more info, but also have a trawl through the forum with the search function using "heater valve" - that should turn up a lot of info.

Cheers,

Chris

Got new valve from ecp, but old one seems to be fine, has a nylon barrell inside, the new one seems to operate no differently to the old one, got my G12 and i'm on it now as we speak. where is it best to release the water from bottom to flush, and where best to run the hose to guys to fill??? If not the valve what else could it be? PS when i removed the valve only a trickle of water came out, expected more???
Bigelsy

Old valve may look to operate fine, but if its worn it may still be letting water past even when off. Are you sure the cable connection to the valve was operating correctly - i.e. moving the valve through its full range of motion from on to off? Maybe if the cable was not attached properly then the slider may look like it was on cold on the dash, but in fact the valve was still partially open?

The piece of steel tube I was talking about that you might need to replace with a nylon one is in the other hose to the one the valve is in (if you see what I mean). Its in about the same position in the other hose in the engine compartment that comes back from the heater matrix. If it hasn't been replaced then it may just be a rusty blob by now  :wink:

Check your Haynes manual for the best place to drain the system. From memory I think I removed one of the lower hoses - from the bottom of the radiator to the water pump I think. Just needs to be a low point on the engine so ayou can get all the water drained out.

When you come to refill then I think you fill via the expansion tank, and probably leave the heater valve on it s hot setting to allow coolant into the heater matrix.

I am sure someone will correct me on this if I'm wrong, but its all from memory and it was over 18 months ago now!!!! Haynes covers the procedure, and if you don't have one I'd suggest getting one now. They are cheap manuals and pretty good for the Mk1 - lots on ebay or on here secondhand if you can't find a new one.

Cheers,

Chris

Thanks Guys! did a full flush from the hose connected to head with garden hose, and removed bottom hose to water pump, till run clear. Just for future reference it was the heater control valve, even though it looked to work fine when removed I tested it with the Garden hose being as I had got it out (just fits nice but you may have to warm the hose up first with hot water to slip it on) turned the valve to ON position, and turned tap on, water flowed normally then closed valve and water still came out proving faulty, tried with new part from ecp and it built up pressure when closed and blew the garden hose off. All put back together and works like new now, Oh! and it was a fuse on my blower that had gone!
Yippee!!!

Glad you got it sorted  8) .

Did you replace the small piece of metal connector in the other pipe with the nylon replacement as well?

Cheers,

Chris

bigelsy and ChrisB

Just to sat thanks to you both after reading this i popped in to my local GSF parted with ?11.06 and now have cold air and hot air when required .
My valve was also original and leaking . No more hot feet in this weather  8)

Cheers Chudd…………

I feel the need to do this too

and I was in there today too dam it :roll:

Chris! checked the metal hose and was fine engine has been looked after with proper anifreeze, pipe was fine, was just the valve, thanks for your help. Was happy to help anyone else that thought this thread useful!!
Again Quality Site. Cheers Drew.

No worries - glad you got it sorted  

Cheers,

Chris

Anyone got any pic of the valve is question?

Also what is it's propper name as I will be ordering a new one asap - I suspect my constant heat is a sytom of the same fault.

Cheers Rob.

Its

17850 HEATER VALVE  Golf 1 >12/83  ?9.50 +VAT

From GSF …………..

chudd said

Its

17850 HEATER VALVE  Golf 1 >12/83  ?9.50 +VAT

From GSF …………..

Cheers fella!
 :wink: