Heater only blows hot air? 94 VR6

[TimA 11]

My heater is only blowing hot air, regardless of where temperature control dial is set. You can hear the control flap thunk as you reach the cold setting, so I am assuming it is not just that the being stuck, or the control cable disengaged ( especially as you can see movement on the cable immediately behind the dial when looking through the radio aperture).

I have just changed the matrix and reclined the various direction and control flaps, but am not aware of any direct link to that- the car was warm before, just with no control over direction of airflow...

Any suggestions on what to do/check please?

Apologies if this has been done to death on previous posts, (am newbie to the forum and a born again owner after multiple corrados in the 90s... when they didn’t have issues like this!)but my searches only find no hot air issues rather than no cold.Frankly right now I would rather have that than steam gently in my own sweat!

Thanks in advance for any help.

[Simeon 0]

You need to replace the foam inside the air direction control box, the factory stuff breaks up over time, usually evidenced by bits of foam getting blown at you through the vents every now and then.

[vw rule 19]

Hello there,

 

the thunk/clunk sound you say you hear, could be the flap is trying to move, but then springs back to original position blocking off cold air and allowing hot air to continuously flow through ?

 

Could be part of toothed cog on flap has broken away.

 

Could be the heater control dial assembly unit, these are known to have problems.

This part is £240 new from VW Heritage.

 

Could be a cable but more then likely it's a problem with the flap it's self or the heater control dial unit.

 

Hope this helps

 

Si

Edited September 28, 2019 by vw rule

[TimA 11]

Thanks but have already done that. As you say, foam had gone and spewed out of vents- so have now re-covered with heat resistant plumbers tape.

Everything was moving correctly prior to re-installing, so was assuming the cause was elsewhere. I’d hoped a thermostat somewhere in the cooling system, or something like that/ but as you can prob tell, I don’t have a clue really!

At least winters coming!!

Many thanks for replying so quickly.

[TimA 11]

Ah- thanks for the spring back idea. I’ll try to find a way of checking that doesn’t involve dashboard out again. I didn’t enjoy that...!

[vw rule 19]

Ah- thanks for the spring back idea. I’ll try to find a way of checking that doesn’t involve dashboard out again. I didn’t enjoy that...!

 

Honestly it could just be a coincidence that this has happened, like I say possibly something has broken ?

 

Or if you've had the dashboard out and striped down the heater box assembly, one of the direction flaps might not be seated/located correctly, or the same with the cable ?

Hence it not fully shutting off hot air.

 

Best bet is operate the heater dial's carefully, before you start removing the dashboard, and look underneath on the passenger side as I'm sure there's a flap there.

 

The heater temperature dial should be smooth to turn in both directions, if you feel any tightness or resistance then this is a clear problem.

The same with the position/directional dial, if this feels tight or very catchy/notchy be careful as it could be close to breaking the rear toothed gear on back of heater control unit.

If you've got the heater control unit out,

check that cables are attached correctly,

plus check the toothed gears as they're known to break or become encrusted with dust/dirt especially after 20+ years.

If this seams ok then fault has to be with the heater box assembly somewhere.

 

Plus the position/directional dial doesn't tend to like being rotated, when the fan is on speed 4, for some reason it prefers the speed dail to be on speeds 1 or 2, anything higher and it seams to feel tight and locks, I've seen this on a few MK2 Corrado's with the later type heater controls.

 

Hope this helps

 

Si

Edited September 28, 2019 by vw rule

[Cressa 44]

I would turn myself upside down and get into the footwells. Remove the side trims and gain access to view where the Bowden's cables attach. Detach each one in turn and move things manually to see if all ok down there. Good luck, as mine was a broken cog, but was replaceable in situ

[TimA 11]

Thanks Cressa- took the upside down advice, and all now solved. Let’s just say that if a mate helps, it’s always worth double checking their work! Cables now swapped and all is good- doh!!

[Cressa 44]

Thanks Cressa- took the upside down advice, and all now solved. Let’s just say that if a mate helps, it’s always worth double checking their work! Cables now swapped and all is good- doh!!

 

I always like a happy ending, well done.

[vw rule 19]

Nice one good to hear you've sorted it.

 

Si