Heater not working, can't seem to find the reason why - Not the heater core or HVAC Flap

[TDISean]

For reference I have 2013 MK7 Golf 2.0 TDI Blue Motion.

Hi All

About a month ago I noticed the heating wasn't working in my car.
I have now found that if I turn the heater controls to max heat & the fan on 2, I will get a little bit of heat from the drivers side vent next to the window & the center drivers side will be luke warm at best. Both the passenger center vent & passenger vent next to the window are cold.

I've been researching the last couple of week but have yet to find the cause of the issue.

The two main issues I have come across are a clogged heater core due to the silica bag splitting & the HVAC flap motor failing but neither of these appear to be the issue.

Heater core
I have removed the trim in the passenger footwell & took the car for a 10 minute drive.
When returning home, I checked both the inlet & outlet pipe for the heater core, both feel hot to the touch. I also checked with a infrared thermometer & both pipes reading around 30C.
I think it should be getting hotter than 30C but as it was only a short drive, I presume this would be hotter on a longer driver but I think the notable thing is that both pipes were around the same temperature.

HVAC flap motor
Next I checked out the flap motor, which I can see moving from passenger footwell when changing the temperature from cold to hot & back again.
There is also a noticeable sound change in the airflow when doing this which I've read is another way to know the flap is okay.
It doesn't sound like there is anything broken i.e. clicking/scraping etc.

Other things to note

• I've seen information about thermistors failing but my model does not use these, I think these are only used in new climate control units?
• The engine temperature climbs normally to 90C & stays there quite happily.
• Coolant has been checked regularly & it hasn't dropped.
• I haven't done a coolant change yet as I'd like to fix the issue at the same time I do the change.
• I did wonder if the issue would be with the heater control valve, but I don't think the heater core inlet pipe would be getting hot if that was the issue?

Any help would be greatly appreciated as the weather is getting colder
Happy to post photos if needed

Many Thanks
Sean

 

[golfdave]

I think there is a reset function that by pressing & holding certain buttons it resets the flaps

Only for Climatronic

I'd also check the control module for any fault codes...

 

[TDISean]

Thanks for your reply

Unfortunately I don't have that control unit. I have the one in the photo below. (Taken from Google)

I have just checked for any fault codes with my OBDII reading but nothing to show

 

[golfdave]

Sorry no further ideas!!!.....

 

[YamR1rider]

I should think you got this sorted out by now, but did you get round to checking out the so called N82 coolant shut off valve? I had a similar problem on my daughters 1.8 Golf TSi, replaced the heater core but it wasn't it - but the valve was. Someone else had written a how to on it, which is here: https://www.vwvortex.com/threads/di...2-heat-taking-a-long-time-to-come-on.9493028/. It may be slightly different for your diesel but principle is the same I'm sure.

For additional info as you mentioned it, it is worth noting that one of the pipes to my heater matrix was also hot even with the defunct valve - it took replacing the valve for the other pipe to become hot. Heat went from nothing/next to nothing to nuclear powered!

 

[joeT]

Kinda off above subject bit climate control related.
2015 Golf TDI SEL so the Climatic (AUTO) heat/AC system installed.
When digital controls in AUTO set for temperature lower than interior ambient there is plenty of cold air from the center dash outlet. When the selected temperature is higher than the interior temp there is no hot air flow from the top of dash center outlet. There is however adequate heated air flow from the outlets near the far ends of the dash that helps kee the front door windows fog free.
I suspect that the conditioned air that would flow out of the dash center outlet when heat called for is instead distributed down into the foot wells from under the dash. (I have confirmed that there is heated air directed into the front footwells during heat mode)
Can anybody confirm my heated air flow pattern theory? Thanks in advance

 

[YamR1rider]

Couple of possibilities I can think of - could be either that a flap motor controlling the door (or one of the doors if climatic) to the heater core is not working properly (or some other circulation flap somewhere else maybe). Alternately, before I fixed the N82 valve per my post 5 above, I noticed odd behaviour of some lukewarm heat blowing out the drivers side but not much out the passenger side (on a regular AC car). Switching the valve out fixed all (along with a replacement heater core, my old one was partially clogged). Not entirely sure on the TDI as to whether they have that valve in the same spot as on the gas powered golfs although I would guess there is something similar somewhere.

 

[allenye2008]

Hey, I'm having a similar issue on a 2015 GTI gas. Did you ever figure this out?

 

[fazGtdlimestone]

Did you sort this exactly same issues with my 2014 gtd


I do have new heater control valve but can't find it anywhere on my 2.0tdi

Image shows we're it should be but can't seem to locate it....

 

[allenye2008]

Did you sort this exactly same issues with my 2014 gtd


I do have new heater control valve but can't find it anywhere on my 2.0tdi View attachment 301892

Image shows we're it should be but can't seem to locate it....

I had the same issue and the N82 valve was the issue. I used the repair manual to help find the valve. It's in the Engine Mechanical, Fuel Injection and Ignition manual: https://www.manualslib.com/manual/2115050/Volkswagen-Golf-2015.html?page=238.

It's kind of hidden away under the air intake and I removed it to access it.

This dude also kinda posted a guide on getting to it: https://www.vwvortex.com/threads/di...2-heat-taking-a-long-time-to-come-on.9493028/

 

[fazGtdlimestone]

I had the same issue and the N82 valve was the issue. I used the repair manual to help find the valve. It's in the Engine Mechanical, Fuel Injection and Ignition manual: https://www.manualslib.com/manual/2115050/Volkswagen-Golf-2015.html?page=238.

It's kind of hidden away under the air intake and I removed it to access it.

This dude also kinda posted a guide on getting to it: https://www.vwvortex.com/threads/di...2-heat-taking-a-long-time-to-come-on.9493028/

Is this same for petrol and diesel vehicles cheers for reply

 

[YamR1rider]

Is this same for petrol and diesel vehicles cheers for reply

I don't have a TDI workshop manual, but my guess is there will be a heater control valve in the circuit somewhere - but it may well be in a different place and/or different size and shape to the 2.0 TSI petrol engines. You could try tracing the coolant lines back from the bulkhead to see if you can spot anything likely, then compare with the various Heater Control Valves for your exact model on somewhere like AutoDoc: https://www.autodoc.co.uk/car-parts...-12319/vw/golf/golf-vii-5g1-be1/59070-2-0-tdi. Looks like there are quite a few variants.

 

[fazGtdlimestone]

Worth a read for anyone with similar problems ordered a matrix with larger holes for water to flow through




I have mine all sorted now. About 6 weeks ago I brought a new heater matrix for £80 the same make that was on the car. Flushed out all the system before installing. Total job took under 2 hours to do myself and haven’t had any problems since plus my heater works again. I think heater core blockage was causing pressure making coolant overflow from expansion tank overflow once it was hot.
I originally thought my old heater matrix was ok as both the in and out pipes were hot once warmed up so I assumed there wasn’t a problem with it and I also thought it must have been something else from stopping my vents from blowing out hot air. I just wish now that I had changed the heater matrix earlier.
But very happy now that I have no problems.
It really is a simple job to do as well with fairly easy access to the heater matrix. Most of the time was spent running the cleaner through the system and then draining it out.

 

[Heathy]

Worth a read for anyone with similar problems ordered a matrix with larger holes for water to flow through




I have mine all sorted now. About 6 weeks ago I brought a new heater matrix for £80 the same make that was on the car. Flushed out all the system before installing. Total job took under 2 hours to do myself and haven’t had any problems since plus my heater works again. I think heater core blockage was causing pressure making coolant overflow from expansion tank overflow once it was hot.
I originally thought my old heater matrix was ok as both the in and out pipes were hot once warmed up so I assumed there wasn’t a problem with it and I also thought it must have been something else from stopping my vents from blowing out hot air. I just wish now that I had changed the heater matrix earlier.
But very happy now that I have no problems.
It really is a simple job to do as well with fairly easy access to the heater matrix. Most of the time was spent running the cleaner through the system and then draining it out.

Nice to hear you sorted your problem, so were you also losing coolant out of the expansion tank? I'm currently losing coolant, it seems like the car runs fine then out of nowhere it will bring up a warning light and the coolant tank is empty, so sounds similar to what you said, I also only have heat on one side but its been like that for a while now but lived with it until Im now losing coolant.

Did the new heater matrix stop your coolant leaking? I'm thinking of doing mine although I don't have a proper jack, only the one that came with the car so not sure about draining my coolant, would maybe have to buy axle stands, maybe it will be doable. Did you do anything specific to clean the system, like can I do it myself easily with basic equipment? Any help would be appreciated as I feel like it's the only thing I can think to try next.