No air from air vents (sometimes)

[halex]

Hi,


I have S204, year 2010 and air-conditioning is working normally, cold-air is going through the vents and sometimes it just suddenly stops and no air is going out throught the vents. The air blower motor is working normally (it is also relatively new).
When it is all ok, air condition is working normally, so it is noisier when I set fan speed up and quieter when I put fan speed down. When air stops going out, you can just feel very gentle blow of cold air from the vents, no matter the fan speed you set there will be almost no air flow out of the vents (the flow of the air can not even move your hair).

After I stopped the car at the gas station to refuel and started the engine again, the air blowing started completely normally like there was no problem before.

No special setting of air-conditioning was used, no re-circulation, it was set on both sides to blow up, middle and down regions and no auto function...

Condenser is also new, pipes are ok, filter for climate control was also changed recently (but not the cabin filter)

Have this strange behavior for last few years, it is a rare, but usually it decides to awake when we go on vacation and when it is very hot

Any hints what could be the problem?

Should maybe replacement of cabin filter help?

Could be some failure in air-condition control buttons unit or some sensor maybe?

 

[brandwooddixon]

I must admit that you're not the only one.
I've had this happen on a couple of occasions, but it usually fixes itself after a restart or if left long enough.
Today the fan stopped working totally and won't restart. The temperature controls work normally as does the air direction, its just the air flow that isn't correct - only flow is when the car is moving.

You say that the motor is working normally. Is this also the case when you have no airflow?

 

[halex]

Yes, blower motor is working just fine (it is relatively new - replaced maybe two years ago). You can hear it blowing normally, reacts on increase/decrease fan speed, but almost no air flow out the vents to the cabin. Then you stop the car (i.e. filling it at gas station) and start it again and all is good. Super annoying and it usually happens when it is very hot, even though when we start journey the climate control is working just fine, and then after few hours (not every trip but on very rare occasions) it just stop sending the air through the cabin (until the restart).

I bought new climate control module for 50€ on eBay (part is new, but was not sold, so it was on a shelf for maybe 10 years) and will try first this.

I also noticed that sometimes when AC is working for a longer time the middle console near to the co-driver left leg (left side drive car) become very hot sometimes. I have manual transmission...

 

[MBremen]

Hello,

Have you managed to fix the problem? I am facing the exact same behavior of air-conditioning.

 

[tavernole]

Hi,


I have S204, year 2010 and air-conditioning is working normally, cold-air is going through the vents and sometimes it just suddenly stops and no air is going out throught the vents. The air blower motor is working normally (it is also relatively new).
When it is all ok, air condition is working normally, so it is noisier when I set fan speed up and quieter when I put fan speed down. When air stops going out, you can just feel very gentle blow of cold air from the vents, no matter the fan speed you set there will be almost no air flow out of the vents (the flow of the air can not even move your hair).

After I stopped the car at the gas station to refuel and started the engine again, the air blowing started completely normally like there was no problem before.

No special setting of air-conditioning was used, no re-circulation, it was set on both sides to blow up, middle and down regions and no auto function...

Condenser is also new, pipes are ok, filter for climate control was also changed recently (but not the cabin filter)

Have this strange behavior for last few years, it is a rare, but usually it decides to awake when we go on vacation and when it is very hot

Any hints what could be the problem?

Should maybe replacement of cabin filter help?

Could be some failure in air-condition control buttons unit or some sensor maybe?

Sound like the fan regulator which is in the fan motor housing and is on its way out, PIAS to replace as its tucked up under the dash on the passenger side

 

[halex]

Hello,

Have you managed to fix the problem? I am facing the exact same behavior of air-conditioning.

I replaced my Climatronic control unit in middle console with the used one and reprogram it. Will need to wait for the Summer to test if this helped. If problem repeats then I will check then fan control regulator as written in last message.

Regarding the hot central console, especially on the passenger side I found out that it happens occasionally when DPF regeneration occurs and you can not do anything about it. It goes up to 600 degrees Celsius, heat shield helps but not perfectly to stay completely cold so you will feel this in the cabin. I don't know how often this occur but I suppose every few thousand kilometers.