W202 C220CDi: Weak Heater (Temp + Output)

[420SE]

Hi guys. It's been quite cold recently and I have noticed that the heater isn't doing it's job.

Symptoms:
1. When I set the temp to max, the temp can best be described as nothing more than lukewarm

2. When I set the air speed dial from 1, say to 5, there is an increase in air output, but it is very very slight

Any ideas where I should start? I initially thought it might have been in part due to a clogged cabin filter situated below glovebox in passenger footwell, but having changed it, the problem is still there..

I have researched / looked into past threads on this but am not sure what to begin with:

1. Duo valve issue?
2. Replacement blower motor motor brushes?
3. Heater control panel needs replacing?



EDIT: found a useful link of heater motor removal, if that is what I will need to do

 

[Stratman]

The first thing to do is change the thermostat, they're a known weakness on these engines.

Luckily it's an easy job, much easier than replacing the heater fan.

 

[420SE]

Thank you Stratman. I did a search and found something here (not exactly same, I know, 6 cyl vs. 4 cyl) but gives me an idea of what I am looking. Hopefully the location isn't far too different on my engine!

HOW TO: Change thermostat - OM648 3.2 I6 CDI engine - Mercedes-Benz Owners' Forums

Where is the best place for a replacement thermostat? Euro Car Parts? Or do I try an online breakers yard?

 

[Dec]

What’s your temperature gauge reading when the engine is up to normal working temperature?

Dec

 

[420SE]

What’s your temperature gauge reading when the engine is up to normal working temperature?

Dec

Are you asking about the gauge that measures outside temp? If so, I will take a reading tonight and compare it to whatever the weather forecast is supposed to be and what the variation is, if any.

 

[Dec]

No, I mean the left gauge on the cluster next to the fuel gauge, it should read about 80c when engine up to normal temperature after a 5 mile drive.

Dec

Edit, I should have said engine temperature gauge, sorry.

 

[420SE]

Hi guys, sorry for the delayed response. I don't drive much on weekdays due to the train commute, but I took the car out over the weekend. Temp outside was mild, about 8 - 10 degrees. After about 25 mins of driving, the temp gauge looked like this:

And a pic of the control unit...if of any use.

What are my next steps?

 

[Ted]

What are my next steps?

See posts 2 & 4

 

[Dec]

Thank you Stratman. I did a search and found something here (not exactly same, I know, 6 cyl vs. 4 cyl) but gives me an idea of what I am looking. Hopefully the location isn't far too different on my engine!

HOW TO: Change thermostat - OM648 3.2 I6 CDI engine - Mercedes-Benz Owners' Forums

Where is the best place for a replacement thermostat? Euro Car Parts? Or do I try an online breakers yard?

Don’t buy a used thermostat, get the correct part for your car at an MB dealers, quote your VIN will ensure you buy the correct part.

Dec

 

[420SE]

Don’t buy a used thermostat
Dec

Morning Dec.

Is the thermostat produced as an OEM item or is it a specialist MB dealer only item?

 

[Dec]

Euro parts or an MB dealer, no idea which is better so would suggest the MB dealer as you will get the correct part for your car, not an expensive item if I recall correctly.

Put in your reg here for an alternative/comparison to the MB dealer… http://www.eurocarparts.com/ … then select > Cooling & Heating >Thermostats.

Dec

 

[420SE]

Euro parts or an MB dealer, no idea which is better so would suggest the MB dealer as you will get the correct part for your car, not an expensive item if I recall correctly.

Put in your reg here for an alternative/comparison to the MB dealer… Euro Car Parts | The UK's Number 1 Provider of Car Parts Online and In Store … then select > Cooling & Heating >Thermostats.

Dec

Thank you for your help!

EDIT: http://www.eurocarparts.com/ecp/c/M...e7c6f378dee704d2483e2da97f8dce540e5f56&000325

Under £23 for a thermostat, made by a company I never heard of before, called VERNET...

 

[Dec]

Did you try an MB dealer to see what the charge?
No idea on brand quality.

Dec