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Volkswagen Golf - Intermittent fan speed issues - Oliver zecchin
I’m hoping someone may be aware of the issue I’m currently facing with the fans on my MK 6 VW Golf. On the occasion that I’m heading out for a longer journey (anything more than an hour), the fans start to play up. The symptoms include; fan speed dial working and changing normally - you can hear the fan speed increase and decrease but the sound is muffled with a minimal amount of air passing through the vents on the highest speed. On one occasion, while travelling at 70mph, the fans on speed 4 directed at the windscreen, not even a light tissue was blown away from the vent. This is frustrating when it’s roasting hot or cold and raining. The issue only presents itself on longer journeys and can be remedied by switching the car off for 1 or 2 hours. On short journeys I have no issues - the car will heat up or cool down as quickly as I need it too. I’ve had the car at the garage but with the issue being intermittent, it’s hard to diagnose - there was work done on the car at the cost of around £250 but this still didn’t remedy the issue. Looking forward to hearing any thoughts on this.
Volkswagen Golf - Intermittent fan speed issues - elekie&a/c doctor
Have you tried it with the a/c turned off ( eco mode) . I suspect the evaporator is freezing up and acting like an ice block , that’s why there is no air flow . ( this is the part that produces cold air ) . What was replaced for £250 ?
Volkswagen Golf - Intermittent fan speed issues - bathtub tom

I had a problem with fan speed on a Skoda Estelle.The resistor had a bi-metallic strip above it that prevented the resistor from running too hot, resulting in the fan speed varying itself at random. Cured by tweaking the spring strip,

Volkswagen Golf - Intermittent fan speed issues - Oliver zecchin
I had the resistor changed when I first noticed the issue but obviously to no avail. I wonder if this spring strip is separate to the new part that was fitted?
Volkswagen Golf - Intermittent fan speed issues - Oliver zecchin
I took the car in today while it was acting up and funnily enough, the mechanic showed me that part and made me touch it. I have to plead ignorance to anything mechanical on a car which is why I’m here! I have this issue whether the car is running hot or cold... I never turn the AC off, I just adapt the temperature to suit the conditions but yes, even when it’s off, I have the same problem. I had a heater blower and resistor changed June 19.
Volkswagen Golf - Intermittent fan speed issues - elekie&a/c doctor
If you can hear the motor running on its various speeds , then the fan and resistor are working ok . The only way to get no airflow is if there is a blockage in the air pathway. Has the cabin filter been checked ?
Volkswagen Golf - Intermittent fan speed issues - Oliver zecchin
Yes you can hear the fan working in every speed. It will work EVERY single time I get into the car and on normal journeys, is fine. Anything an hour or more and the output of air drops substantially. Despite being able to hear the fan, it sounds terribly muffled when it’s playing up. The issue happened yesterday and maintained while I was driving - at the garage while sitting idle for 20 mins, it managed to remedy itself. I couldn’t tell you if the airways have been checked but assume they’re ok as it works fine every day... it’s only on the occasion of a longer journey that it plays up.
Volkswagen Golf - Intermittent fan speed issues - bathtub tom

Have you cleared leaves and debris from the plenum chamber (the bit under the windscreen that feeds air to the heating and A/C)?

What's the state of your cabin filter?

Volkswagen Golf - Intermittent fan speed issues - Oliver zecchin
I clear it from time to time but it never gets clogged... I notice quite quickly when things start to build up.

I can’t help but feel the issue is caused mechanically by a problem part. It always runs absolutely fine but decides it doesn’t want to play ball after an hour or so.
Volkswagen Golf - Intermittent fan speed issues - elekie&a/c doctor
Does this car have manual ac heater system or digital climate control. I’ve never seen a fault like this on a Golf , and I’ve seen a lot of them .
Volkswagen Golf - Intermittent fan speed issues - thunderbird

I had a problem with fan speed on a Skoda Estelle.The resistor had a bi-metallic strip above it that prevented the resistor from running too hot, resulting in the fan speed varying itself at random. Cured by tweaking the spring strip,

But they were clockwork cars. Things have moved on since.

Volkswagen Golf - Intermittent fan speed issues - bathtub tom

I had a problem with fan speed on a Skoda Estelle.The resistor had a bi-metallic strip above it that prevented the resistor from running too hot, resulting in the fan speed varying itself at random. Cured by tweaking the spring strip,

But they were clockwork cars. Things have moved on since.

I quite liked that old car. Unequal length front wishbone suspension, four pot front calipers, semi trailing arm rear suspension and rear engine. Someone once described them as having the same spec as a 911, but if anything could go wrong, it would! I won't list the litany of failures, but the semi trailing rear arms twisted themselves resulting in masses of negative camber and the lack of body stiffness was clearly visible in the rear view mirror, although the road holding wasn't compromised (perhaps due to the negative camber?).

Volkswagen Golf - Intermittent fan speed issues - Oliver zecchin
Manual.
Volkswagen Golf - Intermittent fan speed issues - elekie&a/c doctor
I’m struggling to find a sensible answer to this . When the fault occurs , have you tried switching the air flow to recirculated air ?
Volkswagen Golf - Intermittent fan speed issues - Oliver zecchin
yes tried recirculate too. It’s such a tough one to diagnose. I do appreciate your help...
Volkswagen Golf - Intermittent fan speed issues - Mammoth Man
Hmm, seems no one has resolved this issue?

I’m having the same problem. I started by getting an ODB reader so I can ensure it’s not a thermostat issue (temperature fluctuating on the highway) and it’s not. Got a steady 90-95. Then I thought, maybe the heater core is plugged so I changed that. Still problematic. The Guess none of these would explain a drop is air speed. So weird as it blows so well when you first start the car.
Volkswagen Golf - Intermittent fan speed issues - Mushroom72
Did anyone get to the bottom of this???
I have this exact problem.
Just tried switching off the AC and the blowers are back blowing.
But soon as I put AC back I get bout 10 mins and urge airflow slows again. Can still hear the blowers blowing.
Volkswagen Golf - Intermittent fan speed issues - Rerepo

Maybe A/C evaporator is frosting up due to some defect (thermistor faulty or detached from evap?)...

Volkswagen Golf - Intermittent fan speed issues - bathtub tom

The OP's been asked twice about the cabin filter, but hasn't replied.

Volkswagen Golf - Intermittent fan speed issues - Mushroom72
Ok, would love to pretend to know what you are saying or how to check ??
Can you help? Or should I go to a garage?
Volkswagen Golf - Intermittent fan speed issues - bathtub tom

You don't say what model you've got. Just search youtube for cabin filter replacement for your model and year, or leave it to a garage.

Volkswagen Golf - Intermittent fan speed issues - Mushroom72
Mines a Golf diesel 1.6l 2017
Is it most likely to be the cabin filter?
Volkswagen Golf - Intermittent fan speed issues - Rerepo
Mines a Golf diesel 1.6l 2017 Is it most likely to be the cabin filter?

With all due respect I posted the likely problem already. If the airflow reduces 10 mins after the A/C is turned on the the likely problem is that the evaporator is frosting up. The reason being some failure in the control system or the evap. thermistor is faulty or has detached from the evaporator. You'll need something like VCDS to see what the HVAC controller thinks its doing.

Volkswagen Golf - Intermittent fan speed issues - Mushroom72

With all due respect I posted the likely problem already. If the airflow reduces 10 mins after the A/C is turned on the the likely problem is that the evaporator is frosting up. The reason being some failure in the control system or the evap. thermistor is faulty or has detached from the evaporator. You'll need something like VCDS to see what the HVAC controller thinks its doing.

Sorry, was just wanting to be sure as you’d replied to the OP with suggestions. I was trying to follow the thread. No idea what VCDS or HVAC are/mean. Was looking for advice. Thanks
Volkswagen Golf - Intermittent fan speed issues - Rerepo

Sorry, was just wanting to be sure as you’d replied to the OP with suggestions. I was trying to follow the thread. No idea what VCDS or HVAC are/mean. Was looking for advice. Thanks

HVAC refers to the heating ventilation and air con controller - this is the electronic module that controls the cabin temp and hence the A/C compressor. VCDS is diagnostic software run on a laptop that can connect to a VW car and interrogate the various controllers for data and fault codes. I think its likely that your A/C evaporator is running too cold and frost up, which is restricting the air flow through it. There are several possible causes. A garage with VCDS will be able to interrogate the HVAC controller to get some insight into what the fault might be.

Volkswagen Golf - Intermittent fan speed issues - ifekas
Did anyone get to the bottom of this??? I have this exact problem. Just tried switching off the AC and the blowers are back blowing. But soon as I put AC back I get bout 10 mins and urge airflow slows again. Can still hear the blowers blowing.

For that problem surely the issue is that the evaporator is icing up which results in reduced airflow whilst the air cannot flow efficiently through the fins of the evaporator? Usually this is caused the low refrigerant level but I suppose it could be also caused by a blockage or something restricting the flow of air.

Volkswagen Golf - Intermittent fan speed issues - Mushroom72
Did anyone get to the bottom of this??? I have this exact problem. Just tried switching off the AC and the blowers are back blowing. But soon as I put AC back I get bout 10 mins and urge airflow slows again. Can still hear the blowers blowing.

For that problem surely the issue is that the evaporator is icing up which results in reduced airflow whilst the air cannot flow efficiently through the fins of the evaporator? Usually this is caused the low refrigerant level but I suppose it could be also caused by a blockage or something restricting the flow of air.

As it’s never happened to me before and we’ve had the car for 3 years I was looking for suggestions. Thanks for your help.
Volkswagen Golf - Intermittent fan speed issues - edlithgow

Aircon icing explanation would seem to only be applicable if the problem only manifested when the aircon was in operation, which I understood was not the case?

Alternative (simplistic) theory, without the benefit of any specific knowledge of this system:

C***py German Plastics, known to give extensive grief in the accelerated ageing environment that is Taiwan.

Its theorised to be associated with their (mandatory?) deliberately engineered degradability.

Say a fan turbine, which loosens on its axis as it gets warm with extended operation, and so stops blowing air, though the motor would continue to be audible.

Turn it off and it cools and re-grips and so would work for a while, though I suppose it'd eventually destroy itself completely.

Maybe superglue it, if you in fact can find it, though it might be so much grief to dismantle that you'd prefer to replace it?

Edited by edlithgow on 04/11/2024 at 07:39