W220 A/C blowers eratic

davidslater

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Car: S500 5.0 302BHP
Year: 2004

Noticed last week blowers seemed to have developed a mind of their own!

Turn blower onto A/C or heat and they will come on and run for around 10 seconds. They will turn off very slowly as if I was turning them down.

They will then turn back on randomly and run for another few seconds (anywhere between 3-15 seconds) then slowly turn back off. They might stay off for 1 mintue or 30 minutes before turning back on.

The A/C blows icy cold air when it does come on. So I presume that side of things is fine.

I have tried the following -

1. aircon regassed.
2. Checked A/C for leaks
3. read instruction manual (well, you never know!)
4. Turned off 'Auto' settings
5. Turned on 'Auto' settings.

Nothing seems to work.

Thoughts?
 
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whitenemesis

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You say there is no difference in the blower operation irrespective of having the Auto on or off? I'd expect the blower to remain at whatever setting you have selected when Auto is off but it should slowly adjust up and down as cabin temp changes when Auto is on.
 
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davidslater

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I dont think I explained properly.

1. If I manually set blower speed at level 1 (lowest settings) it will run at level 1 for a few seconds then turn off. If I set it at level 5 (highest setting) It will run for a few seconds then turn off.

2. If I use 'Auto' setting, again it will run for a few seconds then turn off.

In both cases it will randomly come back on run for a few seconds then turn off.

It wont get the temp to the desired setting (whether hot or cold)

It does blow hot or cold air (whichever is set)
The blower does blow
The A/C gas was done and is OK
The A/C was checked for leaks and its OK

I've owned the car for a few years and its never done anything like this.
 
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whitenemesis

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STAR diagnosis would probably be a good starting point but it does sound like the blower regulator pack has or is about to fail.
 
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davidslater

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Ouch! just phoned main dealer and they want nearly £300

Have you got a part number? I'm thinking maybe try ebay for a part.
 

whitenemesis

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A2208210951 £170.04 from MB

Check the part number before purchase.

Always best to get the fault codes read first though
 
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television

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Do turn the auto air con off and try the blower and see if it will keep running, set it to hot if need be, and see if the fan will run uninfluenced from the auto setting.

It could be the reg pack and if it is you can buy much cheaper than from Mercedes, Ebay for a start or ECP. It is under the dash and the motor usually has to be dropped.
 
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davidslater

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Do turn the auto air con off and try the blower and see if it will keep running, set it to hot if need be, and see if the fan will run uninfluenced from the auto setting.

It could be the reg pack and if it is you can buy much cheaper than from Mercedes, Ebay for a start or ECP. It is under the dash and the motor usually has to be dropped.

I've tried with heat up full and adjusting fan speeds in 'Auto' and 'Manual' modes with A/C off and it does exactly the same thing - blows for a few seconds then turns off then comes back on randomly while driving.

Is this the part I need? -http://www.ebay.co.uk/itm/Heater-Blower-Resistor-MERCEDES-C-CLK-E-G-S-SL-SLK-2208210951-/261090953566?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3cca3bc95e

Maybe the dealer thought I wanted the whole unit including blower?
 

whitenemesis

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Seems to be the correct part number and a good price! Always good to have the dealer price as a benchmark though as some ebay "bargains" are anything but!!


The blower itself is £423 from MB ...
 
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television

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I've tried with heat up full and adjusting fan speeds in 'Auto' and 'Manual' modes with A/C off and it does exactly the same thing - blows for a few seconds then turns off then comes back on randomly while driving.

Is this the part I need? -http://www.ebay.co.uk/itm/Heater-Blower-Resistor-MERCEDES-C-CLK-E-G-S-SL-SLK-2208210951-/261090953566?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3cca3bc95e

Maybe the dealer thought I wanted the whole unit including blower?

Yes that is the part :D:D I do not think it is the motor brushes as it would not be that constant.

If you would like the fitting instructions then I can send them to you.

Mercedes do charge some stupid amounts for these things.
If you had a voltmeter you could measure the input to the reg pack where it should be 0 to 5 volt depending on the output setting
 

whitenemesis

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You might find this video helpful, if you wish to DIY

[YOUTUBE]93AuDb9Yoik[/YOUTUBE]
 
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davidslater

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Thats a great video. I'm going to order the part and give it a go.

Cheers guys!
 
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davidslater

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I'm thinking I may as well change the filters while I have the covers off.

1. Whart are the part numbers for Charcoal filters (near blower fan assembly)
2. What are part numbers for filters in glove box

Thanks guys
 
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davidslater

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Got both sets of Mann Hummel filters for £60+VAT from Andrew Page (after a bit of haggling!)

Hopefully regulator will be here tomorrow and I'll be able to let you know how it goes

Fingers crossed!
 
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davidslater

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Just a quick update -

I changed the regulator and filters. The fans and air con are working perfectly!

Thanks for all the help guys.
 
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