Club 80-90 Forums

Can anyone tell me how to fix the heater in my T25 please?
I cant switch it off. Its on all the time on hot, unless i take the fuse out, then it blows cold!

Thanks
Cherryboo

Surprisingly, Im getting quite good at this repair malarkey

I'm going to guess that the heater valve (which sits 'brilliantly' out of the way behind the radiator) is either not working and letting hot water bypass into the heater matrix, or the bowden cable (like the ones on a pushbike brakes) that runs between the lever on the dash and the heater valve is bent or broken.

If you drop the spare wheel and lie on your back and shine a torch up behind the radiator you should see the valve and the cable hooking on to it. Get someone else to operate the lever in the cab and see if that works the valve by moving the 'arm'. If it doesn't, your cable is likely bent/broken and replacing could be a pain. If it does, then the valve itself might be faulty. Mine was and I replaced it with a new one... but I believe you have to drop the radiator to do this. My cable was bent too, but I had the dash out and managed to get it working again.

If it is the cable, you can shut the valve off manually by moving the arm down with your hand - leaving it shut means no heat. You could then move it open again in the winter!

E D I T: Removing fuse should make no difference to the heat, but would stop the fan operating

Cheers,
Stu

Its sounds a bit complicated but i will have a look to see if anything is adrift under there!

When i take the fuse out it still blows but only cold air.........is this not normal then?

Thanks
cherryboo

So, typed a long reply this morning that my phone decided not to post so here goes again:

Based on my 1985 DG-engined van, basically...

Van has a coolant system that cycles water around - hot water goes through the main radiator where is it cooled and sent back through the engine block where it warms up again, and so continues the cycle. Now, in that network of pipes is a junction which has a valve. When the valve is open, hot water flows up and through a heater matrix (smaller version of the radiator). The matrix lives inside a heater box behind the dash which also contains an electric fan - operated via the switch on the dash (settings 0,1,2,3).

Fresh air enters the van through the top grill and flows into the heater box, through the matrix and out through the vents. If the heater valve is open, the matrix is hot, so the air passing through gets warmed up. If it is closed, the air passing through is cold.

The function of the fan is simply to increase the volume of air that passes through the matrix. Removing the fan fuse means no blower will operate and the only air that comes through is pushed through naturally as the van is in motion. But.. if the heater matrix is hot (ie. valve is open), you'll still get warm air.

Now.. on some vehicles, some vents do not pass heater matrices - normally those that are pointed at the face to prevent drowsy drivers. I'm not sure if the T3 has this feature or not, others may know better.

Im summary, nothing in a water-cooled heating system is heated electically - so removing the fuse is the same as turning off the fan in this case and should make no difference to temperature.

If valve is not shutting from the lever, shutting it manually is really easy:

* undo (19mm?) bolt under front bumper
* carefully support spare wheel carrier and pull sprung clip
* lift out spare wheel
* lie on your back with a torch and look straight up behind the radiator
* you'll see two rubber hoses, one with a black plastic unit in line - this is the valve
* small, metal lever on the valve can be moved up and down to open and close valve

Cheers,
Stu

Stu, Thank you for your very helpful advice.........i think iv fixed it

cherryboo

Cherryboo wrote:Stu, Thank you for your very helpful advice.........i think iv fixed it

cherryboo

Good news

"If valve is not shutting from the lever, shutting it manually is really easy:

* undo (19mm?) bolt under front bumper
* carefully support spare wheel carrier and pull sprung clip
* lift out spare wheel
* lie on your back with a torch and look straight up behind the radiator
* you'll see two rubber hoses, one with a black plastic unit in line - this is the valve
* small, metal lever on the valve can be moved up and down to open and close valve"

Or,the easy way:
remove gearstick gaiter and it is just to the right of the gearstick. - much easier.

I had a similar problem on my van and upon investigation i found that the valve was unable to be fully closed because whoever had the van befor me had put the Jubilee clip on in such a way as to stop the lever from travelling its full length.......I hope that makes sense...I loosend the clip and moved it round so the lever could reach the "stop" which meant it was fully closed......simples

I also had to straighten the cable a little as it had been deformed by bieng pushed to close the valve but the valve's lever was being fouled

Hi, I recently removed the internal heater and matrix etc, and then couldnt remember which way round the coolant hoses go on the heater/blower matrix.

Am I right in thinking that it doesnt matter as the water goes in and over the metal teeth and back out again, so it doesnt matter which way round to put it?

anyway it seems to work

I would say it doesn't matter