Heater Blowing Cold Air

[2007GTI]

UPDATE:

History so far, heater blowing intermittent cold air for ages.

Faults found with:
Heater support pump
Temperature flap positioning motor

Both replaced and faults cleared.

After above, it was blowing hot about 80% hot, but only on passenger side, drivers side was lukewarm warm at best, after engine running for 30 mins.

However took the car out early yesterday for 50 miles on motorway, it was -1 outside, and it never got as hot as when the above was fixed, barely warm.

On the way home in late evening it was 7 degrees outside and it got a little bit warmer, but not like it was after above two parts were replaced.

I keep thinking it is the matrix, but tea bag is has been removed and wasn't split, plus my mechanic says unlikely, as both pipes to the matrix are burning hot.

Rescanning again this morning and this fault has reappeared:

Activation A/C compressor
Fault code: B10A911

Just found this, might be pertinent:

https://static.nhtsa.gov/odi/tsbs/2014/SB-10070416-2280.pdf

I checked and I have AC firmware version 0805 and the newest is 1001

Answers on a postcard....

[DanDuda48]

My GTD from 2016 has FW 1001 (H03), but my GTI from 2018 has FW 1801 (H04); so obviously, 1001 is not the latest firmware. But someone else needs to advise how to update it...

[2007GTI]

Thanks, I guess that service bulletin is old!

But wouldn't your 2018 car be a 7.5, might be different?

[DanDuda48]

Yes, 2018 GTI is Mk7.5 with firware 1801

[2007GTI]

I've been thinking, it can't be the firmware, as it worked fine in my ownership for 7 years!

So it has to be something else, but I am at a loss to understand what.

Anyone else got any ideas?

[2007GTI]

I'm thinking now that it might be the heater control valve:

https://www.vwvortex.com/threads/diy-coolant-shut-off-valve-n82-heat-taking-a-long-time-to-come-on.9493028/

[2007GTI]

I or my mechanic still can't get the bottom of the issue, of the main heat coming out of passenger side, and it being like warm drivers side.

Found this today in the footwell, maybe it's fallen off something behind the dash?

[CS#303]

That looks like the little cog on the glovebox arm that slows down it's opening.
I guess you or your mechanic  have had the glove box swung all the way down as part of the investigation.
This cog can fall off if you don't unclip the arm properly before swinging it all the way down.

I would say you problem sounds a lot like an actuator problem.
If there is hot water at the matrix but not at the vents then I would think the control flaps that mix the hot air from the matrix with the cold air intake, to get the desired temp, and then distribute it are not effectively working.
Diagnostic scans will only show electrical problems with the actuators, if the actuator has become disconnected form the flap then it will move as per the electrical commands but the control flap will not.

Only my 2p worth, but hope it helps.

good luck!

[2007GTI]

Thanks, yes I thought it might be from glovebox!

We already replaced the right temperature flap motor (VW part 5Q0907511K) and that stopped the clicking noise in the dash and cleared the fault.

Actuator sounds probable, but we can't see any issues with the other ones that are visible, so it must be deep in the dash. Hence we are a bit stumped about how to get to it, unless if you take about the headunit you can get to it? Anyone have an exploded view of the that area?

[madstaff]

Download the workshop manuals too see whats what behind the dash and how to take it all apart.

https://www.dropbox.com/scl/fi/9frg8zxrgde7cja32c4n1/2017-VW-Golf-GTI-Manuals.zip?rlkey=7dagos7l6rwnc1th7imk824i0&e=1&dl=0