W210 Blower Speeds/heat not responding

[Cornish Pasty]

I have a problem with my blowers on my E300 TD. It is a 98 model and has the manual rotary controls. The issue I have is that it seems to have a mind of its own! No matter what speed I set the fans to they generally do not change from what can only be described as asthmatic, also they do not blow hot air. Then for no reason as far as I can determine, they will on occasion start to blow harder and then hot as well, once this happens I can adjust the heat and to a certain degree the fan speed too. What is the problem here?! Please help, I am at my wits end and coming up for winter I would dearly love to feel my hands while driving!

 

[jberks]

The problem with the fan is either the fan bushes or the regulator. Both will give similar symptoms. You need to test the regulator first (do a search on fan regulator) and go from there.
Whether the lack of heat is related to the lack of airflow it's harder to say but start with the fan.

 

[television]

A few things here, the carbon brushes in the fan could be worn out and the incoming air forces a start, if the fan always work on the minimum setting and not the rest then the reg pack faulty.

If the air is always cold then this will be the duo valve or the pump that pushes the water around the heater circuit

 

[Cornish Pasty]

Thank you!

Thanks for your help. The air is always cold until the fan starts blowing harder, then the air temp can be adjusted as normal using the dials. Any thoughts?

 

[television]

Does the fan change speed on all of the speed settings, the circulation pump could be at fault you can feel and hear if it is running

 

[Cornish Pasty]

Does the fan change speed on all of the speed settings, the circulation pump could be at fault you can feel and hear if it is running

No, the fan speed generally tends to stay the same regardless of the position I change the knob to. As I said in the original post, on occasion I can change speeds but that is a rarity and not the norm. Someone I spoke to said it may be the rheostat?

 

[television]

If the fan speed stays the same regardless of the setting, then either the reg pack is at fault or the control unit is not putting out the 0 to 5 volt that controls the speed, you can access the output from the control unit on the reg pack, there are only 4 connections to it
plus 12 volt
output to the fan
input from the control unit
Ground

 

[bigasotonuk]

Hi,
To butt the trend here I think your problem is the heater dash panel itself, agreed if you have fan blower fault it would be brushes or speed regulater, and if you had heat output issues the chances are it would be the heater valve, but to have both, it would have to point to something that effects both fan/fan speed regulation and heat output, especially as you say the air temp is not warm until the heater fan speeds up.
I notice you are in Cornwall, a good source of MB spares Mercman are in Hayle Cornwall.

 

[television]

Hi,
To butt the trend here I think your problem is the heater dash panel itself, agreed if you have fan blower fault it would be brushes or speed regulater, and if you had heat output issues the chances are it would be the heater valve, but to have both, it would have to point to something that effects both fan/fan speed regulation and heat output.

The complete thing is one could say is the engine always getting up to the 85c or more.

One has the circulation pump, by putting a screwdriver blade on the pump and the handle to your ear you can hear if that is running.

One has the duo valve that determines the hot or cold air, one can set this to max hot, if you put a finger on either out pipe you can feel the pulse about 3 per second.

The fan is only controlled by the control unit and I have put up the way to test that above

 

[bigasotonuk]

Well I,m not saying that I,m correct, but I maintain my diagnosis according to the described faults with O/P's vehicle.
Having had to replace a set of manual heater controls on my C230K, these panels can fail, IIRC mine failled because of fan a speed fault, problem was intermittent, I replaced the control panel because when you pushed the old control panel together the fault would dissappear, as the signal for the heater valve comes from this panel, and as the OP said that the heater air temp increases when the fan kicks into life, this to me seems more likely to point to a control panel fault rather than two separate faults from two different parts failing.

 

[television]

Well I,m not saying that I,m correct, but I maintain my diagnosis according to the described faults with O/P's vehicle.
Having had to replace a set of manual heater controls on my C230K, these panels can fail, IIRC mine failled because of fan a speed fault, problem was intermittent, I replaced the control panel because when you pushed the old control panel together the fault would dissappear, as the signal for the heater valve comes from this panel, and as the OP said that the heater air temp increases when the fan kicks into life, this to me seems more likely to point to a control panel fault rather than two separate faults from two different parts failing.

Well I have told him how to check the control unit

 

[bigasotonuk]

Thinking about it (it was about 7-8 years ago now) when I had my faulty control Panel I use to be able hit the dash above the heater panel and this use to fix the fault, but it got worse and worse until it no longer fixed the issue.
Just a thought the O/P could also check the control panel heat control by simply unplugging the heater valve as IIRC with it disconnected it will automatically defaults to max heat, then if the heat is there when the fan is not working correctly and then goes when the valve is reconnected then this would point to the panel.

 

[television]

Any of these control units can get dirty switches, removing the cover and a good blast of non drying switch cleaner in all the switches. the fully automatic press button versions are re known for this problem

 

[kito]

kito

Hi sounds very much like the blower resistor regulator have a look at this Ebay page

http://www.ebay.co.uk/itm/MERCEDES-...rcedes-Benz|Plat_Gen:W210&hash=item4cff457974