Golf 7.5 HVAC issues on long journeys

Golf 7.5 HVAC issues on long journeys

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roltyid

Original Poster:

234 posts

204 months

Wednesday 7th September 2022
quotequote all
An issue I've encountered a few times on my MY18 7.5 Golf R is that on a longer drive of 3 hours +, I lose any meaningful airflow from the vents and it feels like the air-con is no longer functioning. Essentially, I end up with weak, uncooled air from the vents.

The blower is still running and even on full power, the air from the vents is very weak. It seems like the air isn't being directed where it should be.

However, leave the car overnight and all is well with full control over the vents available and cool air available (although not as good as I would expect, so likely a re-gas required as well).

A bit of digging suggests this could be related to the cabin temperature sensor - the issue only occurs on longer drives and after the car has sat for a while, the issue is gone.

Any ideas?

catso

14,854 posts

274 months

Wednesday 7th September 2022
quotequote all
roltyid said:
An issue I've encountered a few times on my MY18 7.5 Golf R is that on a longer drive of 3 hours +, I lose any meaningful airflow from the vents and it feels like the air-con is no longer functioning. Essentially, I end up with weak, uncooled air from the vents.

The blower is still running and even on full power, the air from the vents is very weak. It seems like the air isn't being directed where it should be.

However, leave the car overnight and all is well with full control over the vents available and cool air available (although not as good as I would expect, so likely a re-gas required as well).

A bit of digging suggests this could be related to the cabin temperature sensor - the issue only occurs on longer drives and after the car has sat for a while, the issue is gone.

Any ideas?
I had a very similar problem with an Audi A3, 3.2 same base as Golf? (though older model) it would make all the right fan noises but little and not cooled air would exit the vents, as it was under warranty it went to the dealer and IIRC they changed something to do with the flap controller, not sure if temperature related?

Some years later it would do it again but only occasionally and, as you say after having been on for some time but it would be immediately OK if I switched off and restarted. However I never got to the bottom of it then as I traded it in against the S4 so it became the dealer's problem.

Dr G

15,403 posts

249 months

Wednesday 7th September 2022
quotequote all
Sounds like a stuck flap motor.

There's a little gear on the side of the heater box (behhind glove box, basically) that can shear and do similar. There's also a means of resetting the limits on them through the control panel.

https://youtu.be/KJhaL65HL9Q?t=15

The latter worth a quick try yourself certainly.

roltyid

Original Poster:

234 posts

204 months

Thursday 8th September 2022
quotequote all
Dr G said:
Sounds like a stuck flap motor.

There's a little gear on the side of the heater box (behhind glove box, basically) that can shear and do similar. There's also a means of resetting the limits on them through the control panel.

https://youtu.be/KJhaL65HL9Q?t=15

The latter worth a quick try yourself certainly.
Thanks - I've done the limits reset a couple of times and sometimes it seems to work OK, and other times not in that I don't seem to get all of the vents blowing as it cycles through the settings.

It seems like it's an intermittent fault, rather than a failure of a component as sometimes it works OK, then on a longer run, it doesn't.

catso

14,854 posts

274 months

Thursday 8th September 2022
quotequote all
Dr G said:
Sounds like a stuck flap motor.

There's a little gear on the side of the heater box (behhind glove box, basically) that can shear and do similar. There's also a means of resetting the limits on them through the control panel.

https://youtu.be/KJhaL65HL9Q?t=15

The latter worth a quick try yourself certainly.
That sounds like what happened to mine the first time at least, as I recall the dealer mentioning flap, motor or controller and then later when it did it again the symptoms were exactly the same. Sounds like a common problem.

Dr G

15,403 posts

249 months

Thursday 8th September 2022
quotequote all
Mk7 climate control isn't great. The AC is "acceptable" when working perfectly, the heater matrix is prone to clogging, and the flap motors can die too.

jimmy156

3,711 posts

194 months

Friday 9th September 2022
quotequote all
My mk6 GTi does this, although its worse when heating the air, rather than cooling it!

I will have a look at the youtube link as that could be useful!

thebraketester

14,711 posts

145 months

Friday 9th September 2022
quotequote all
jimmy156 said:
My mk6 GTi does this, although its worse when heating the air, rather than cooling it!

I will have a look at the youtube link as that could be useful!
My mk5 does it too.