Golf2

[KARL]

I am looking for advice from those experienced in repairing the heating and ventilating system in a VW Golf2.

Everything works well except that there is only lukewarm air coming at the hottest setting. The engine runs steadily at the correct temperature range and from starting cold the in and out hoses to the matrix both heat up rapidly with the return probably less than a minute behind the flow hose as I would expect with this car. The fan works fine.

By observing movement at the base of the assembly, the lever seems to activate the flaps correctly and they make the right noise.

What is most likely to be the cause of the lack of heat delivery into the car's interior ?

[TWR]

Blocked Rad, Air Lock in the System, Thermostat.

[KARL]

If the radiator were blocked to a significant degree then the engine would overheat - it does not so this is not the cause.

If the thermostat were failing to open then the engine would overheat. As above, this is not the explanation.

If the thermostat were permanently/stuck open then the engine would be slow to heat up and never reach the correct level - this is not happening so this is not the explanation.

If there was an airlock in the system then flow through the heater would be reduced or even stopped altogether. The return hose heats up rapidly and reaches the engine temperature which suggests the flow is healthy. I cannot see this being a likely explanation.

[Gavmacp]

Your heating matrix has a blockage. The water just bypasses it. Some heating matrix are easy to change some can be a complete nightmare.

[TWR]

It seems you don't need advice Karl.

[KARL]

The bypass suggestion is interesting. I had up to now assumed that, since the flow and return heat up rapidly, the water passes through the matrix - I was unaware that a bypass possibility existed (not familiar with the setup). Is there a way to try to flush away any sediment or whatever without dismantling the dashboard and replacing the matrix, what is most likely to achieve this ?

The car was first registered in 1990.

[tonyav]

Have a look at this, KARL.

https://www.youtube.com/watch?v=4c1cjA-y7yE

[SirOracle]

Agree with Gavcap. You probably need a new matrix,as it has been in the car since 1990.

[tonyav]

Heres a vid showing you how to flush the heater core / matrix.

https://www.youtube.com/watch?v=M9SIafVsqyc

[KARL]

Tonyav; One word: Brilliant......and then several more: Thank you very much.

Now I need to get the bits and find the time to try these out, flushing first. Thanks again.

[tonyav]

Your welcome.

[KARL]

It's sorted - flushing made no difference (very little sediment) but the flaps/doors were needing relined. Once that was done the heater/ventilator works as new. Many thanks again, tonyav.