A/C issue - low fan speed.

[innerfire]

Hello everyone,

Firstly, i want to apologize for my not so good english.
I am a proud owner of one classic beauty - W124 1990 200 E model.

From about a month I have strange problem with fan speed of my climate control.

So the problem is expressed in:
When i start the car (doesnt matter if the car got to working temperature or not) my fan speed is very low. The problem occurs only when it is cold outside, so basically when the climate should heat up the interior. The air from the heating vents is very hot, only the fan speed isnt blowing with correct speed.

The problem doesnt occurs when i change temperature with temp. wheel to cold. In cool mode the fan speed gets high and it blowing on its maximum.

* Just to mention - I have made my own fan speed regulator, but the problem is not in it, because before experiencing the problem my fan speed worked perfect.

I measured control voltage to my fan speed regulator and it is on its minimum - 1.80 V, but I think it should be aroung 4.5-4.7 V until the interior temp. gets to temp. which is selected by the temp. wheel.

So control voltage is sent to fan speed regulator by CCU, on the basis of which measurements?

I think it is possible to have a faulty temp. sensor.
Does anyone experienced such issue?

Thank you in advance!

 

[ItalianTuneUp]

I don't know the problem you're having exactly, but just to mention a couple of things...

1. If I have climate temp set to, for example, 21 degrees and air con set to auto then the fan speed is slow to start with...because when the engine is cold there's not much heat available.

2. Once the engine has warmed up, the air con fan speed increases automatically (still set to auto) as there is now some heat available to warm the cabin.

 

[innerfire]

Thank you for the answer.

That is correct.I drive it on Auto fan speed all the time. Fan speed should be increased when engine temp gets to 60 degrees, but mine doesnt. But it worked fine before few months i dont know what is the cause..

I forgot to mention, some time while driving, all of a sudden the fan speed gets on correct speed for a second and after that stops again. This repeats a couple of times for a few seconds and again all of a sudden it stops to change fan speed and it gets to usual fan speed - i.e 1.8 V.
Just to know what i am talking about, it will do the same if im turning fan speed MAX to LOW fast.

It is very stupid problem and i am very mad, because i cant find where the problem is...

 

[ItalianTuneUp]

If you set the fan speed to max, does the fan blow quickly?

Does your engine reach 90 degrees after it's been running for a few minutes? I was wondering if the thermostat is ok.

 

[innerfire]

Yes, if i push the MAX fan speed button, the fan blows with maximum speed.

The car reaches 90 degrees. Thermostat is OK.

Duo Ventile is OK, because heat flow is stopped when changed to cooling mode.

Im not sure about the coolant circulation pump which supplies the heat vents.
Should i hear it if it works or not? Any method for testing it? Because if i remove it, i will have problems with air in the system.

But when i start fan to max speed manually, i get hot air from vents..

Which sensors should i check too, except the one which is located on the ceiling illumination panel?

Thank you!

 

[innerfire]

Hello,


I solved the problem. The problem was in the fuse for the blower motor, which is outside of the fuse box. (next to the driver's side MacPherson pad).




Thank you all for your help.