VW Golf Mk2 Owners Club

No heat from heater

October 02, 2021, 12:04:58 PM

Hi Everyone,

I have a '91 1.6 Driver that I got in July. I've just discovered no heat comes from the heater (first time using it!). Any ideas why?

Thanks.

Re: No heat from heater

Reply #1 – October 02, 2021, 12:24:36 PM

I think its a blocked heater matrix.
scs

Re: No heat from heater

Reply #2 – October 02, 2021, 12:33:01 PM

Are the water pipes hot that go through the bulkhead? If not you may need to get rid of an airlock.
If that is the case then squeezing the various water hoses whilst the engine is idling should do the biz.

Re: No heat from heater

Reply #3 – October 02, 2021, 01:09:47 PM

Thanks for the info'. Absolutely bucketing down here, and I don't have a garage. I'll give that a go tomorrow and see whats, what.

Re: No heat from heater

Reply #4 – October 02, 2021, 01:54:14 PM

Maybe not blocked matrix, more likely if you still have the bypass valve fitted it will be that blocked. Either way probably wise to replace the matrix so it doesn’t pop then remove the bypass, no longer needed with a new matrix and replace the 2 heater hoses that will have been cut for the bypass with mk3 ones available new.

The bypass is an 90s recall that vw did as a quick fix to poorly designed matrix that would burst and spray occupants feet with boiling hot coolant.

Matrix design was changed so all new ones shouldn’t need the bypass. But make sure you get a reputable brand.

Re: No heat from heater

Reply #5 – October 02, 2021, 01:55:25 PM

Or could be the foam has all gone, so water system is fine, does it get hot when stationary?

Re: No heat from heater

Reply #6 – October 02, 2021, 02:17:21 PM

I hope for your sake it isn't the heater matrix. But if it is you will learn all about what is behind the dashboard.
It's raining here too. Just been under the Caddy on the drive. That wonderful sensation of rain dripping on my bottom half whilst trying to replace the big ends.
Where did summer go!

Re: No heat from heater

Reply #7 – October 02, 2021, 02:49:58 PM

Recent GOV.UK survey cited 91% of people are satisfied with their lives.
The other 9 percent own a Volkswagen.
I would get out more but it’s raining cats and dogs here as well.

Re: No heat from heater

Reply #8 – October 02, 2021, 05:50:56 PM

I've half dismantled the dashboard, and the foam is all gone from inside the heater box. Should be dry tomorrow so going to try and cover the adjusters with heat proof aluminium tape.
Thanks for all the advise.
Will keep you updated...

Re: No heat from heater

Reply #9 – October 03, 2021, 12:04:17 PM

So...

There was no foam on the heat box adjusters, so I've covered them with heat proof tape and cleaned out all the foam bits.
I ran the engine while doing this, and when I first put the heater on, the air was hot for maybe 20-30 seconds.
I've just used the car for 30 minutes and the heater is warmer than before, but still not really warm.
Yesterday I checked that all the pipes to the heat matrix were hot (they are), ran the car with the expansion tank lid off and massaged various hoses while the engine was running. I've recently had the thermostat housing replaced and since then the temperature gauge is significantly lower/cooler. I'm also fairly sure the heater was warmer before the housing was replaced, but I've not really used the heater since having the car.

Any ideas?

Thanks.

Re: No heat from heater

Reply #10 – October 03, 2021, 12:23:51 PM

Is the temp gauge in the middle when fully warm?
Re replacing the foam. Just clarify which foam you have replaced. It's the foam on the flaps in the heater box that disintegrates and needs replacing.

Re: No heat from heater

Reply #11 – October 03, 2021, 01:08:04 PM

Hi, yes it's the foam on the flaps in the heater box I've replaced.
No, the temperature guide never moves above 1/4 hot. Before the thermostat housing was replaced it would go above half when in traffic, but since the repair it doesn't go anywhere near that high. Not sure if the garage replaced the thermostat when they did the housing, or if the coolant system was flushed. I will check when they open tomorrow, but I'm thinking maybe the thermostat is stuck open and/or it needs a coolant flush (or 3!).

Re: No heat from heater

Reply #12 – October 03, 2021, 01:20:34 PM

I had this issue on a previous car any selection of fan speed above one and the air would start warm but quickly blow cold even though the engine temperature was normal. I was convinced it was a blocked matrix. I never cured the problem even following flushing and loads of fiddling. note I did not replace the matrix.

Re: No heat from heater

Reply #13 – October 03, 2021, 02:35:56 PM

When the engine is fully warm do the water pipes get very hot to touch? The bottom rad pipe from the thermostat should be very hot to touch proving water is getting to the radiator. Obviously be careful putting your hand near the drive belt (might only be an issue if you have PAS).
It also might be worth flushing water through sections of the cooling system (hose pipe) to ensure no blockages before flushing with distilled water and re-filling.

Re: No heat from heater

Reply #14 – October 03, 2021, 02:55:33 PM

Have just checked, all radiator hoses get very hot. Checked paperwork from garage and it wasn't the thermostat housing that was replaced it was a housing elsewhere, so I'm still thinking it could be the thermostat stuck open?
Am currently running a coolant flush through to see if this does anything, can't say I fancy flushing things with the hose, I can see that going very wrong