P6B - heater not working

[Shed_1978]

Hi All,

Now I've started to use my P6 in the cold - I've realised my heater isn't working.

The 2 speed fan works a treat either in the demist or interior position, but it just blows cold the whole time.

Any ideas / pointers on where to start.

Thanks,

Steve

 

[rockdemon]

I'd check the levers that the rods activate on the side of the heater box are moving freely....

 

[The Rovering Member]

The matrix is probably bunged up with accumulated crud, unfortunately necessitating removal for rodding or replacing. You could try back-flushing it but I've always found it to be pretty ineffective if not a complete waste of time.
If you were very lucky it could be air-locked but I wouldn't count your chickens.

 

[GrimV8]

When the engine is up to temperature are the heater pipes hot or cold?

 

[keanej]

Hot water flows through the heater matrix all the time, a flap mixes the hot air with cool air to give temperature control.

So if the pipes going into and out of the heater box are hot then it will either be a blocked heater matrix or heater flap not moving.

Get someone to move the temperature control lever while you watch the side of the heater box - can you see the controls moving ?

You could try back flushing the heater to clear any silt, but really descaling the heater matrix is best and can work, it does need some patience though. I just did my P4 which is now really warm.

You'll need to remove it from the car, soak and flush with a good descaler bought from a plumbers merchants do this several times and leave immersed in the descaler to give it chance to work. I did this over a couple of days. It will also give you chance to examine the heater flaps.

 

[Shed_1978]

Thanks for the pointers Gents, I'll do some investigating.

Steve

 

[quattro]

Thanks for the pointers Gents, I'll do some investigating.

Steve

There are several types of descaler available from the plumbers merchant.

The delicate metal descaler, based on formic acid (ant bite) are the best for this purpose as they don't attack metal. This can foam like you would not believe though so have plenty of space around it.

Hydrochloric acid types, even inhibited grades, can dissolve metal and cause major problems. Do not attempt to use either of these with the heater still in the car as they can leak and dribble acid all over your vehicle's insides including the carpet which it will eat.

Do not breathe the fumes either, they can kill you.

Apart from that - have fun

 

[adamhotrod]

Do not breathe the fumes either, they can kill you.

Apart from that - have fun

 

[ghce]

It is not an ardous task to remove the heater box, in fact probably easier to remove it than to do an insitu descale and it gives the option of a flap inspection too, from memory it only took me about 45 minutes to an hour to remove the unit and other than having to use a long extension socket upside down under the dash was as bad as it got.

Graeme