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Word of warning - heater control case 07-09

591 views 4 replies 3 participants last post by  Noodles 
#1 · (Edited)
Hey everyone,

Just to make you aware of a potential issue, for cars with the Behr 2118300360 evaporator case on the firewall, there's a defect built into the original part which is a bit of a sleeping time bomb. There's a design defect in the original part which allows the passenger side defroster control flapper to over-rotate when you command the defroster to the "on" position. The flapper actuator over-rotates, causing the plastic limit stop to be pushed down over time and, eventually the actuator gets stuck when the door finally binds and fails. It does throw a code for a failed actuator, although I'm not sure what code it specifically is. If your passenger side windshield defrost vent is unable to be shut down and your air is limited as a result out of your passenger vents, you've got the problem. These are the cars the part is used in....

Mercedes CLS 500 Coupe 2005, 2006
Mercedes CLS 55 AMG Coupe 2006
Mercedes CLS 63 AMG Coupe 2007, 2008, 2009, 2010, 2011
Mercedes E 280 4MATIC Sedan 2007, 2008, 2009
Mercedes E 280 RWD Sedan 2007, 2008, 2009
Mercedes E 320 4MATIC Sedan 2004, 2005
Mercedes E 320 4MATIC Wagon 2004, 2005
Mercedes E 320 CDI Sedan 2005, 2006, 2007, 2008, 2009
Mercedes E 320 RWD Sedan 2004, 2005
Mercedes E 320 RWD Wagon 2004, 2005
Mercedes E 320 Sedan 2002, 2003, 2004, 2005
Mercedes E 320 Wagon 2004, 2005
Mercedes E 350 4MATIC Sedan 2006, 2007, 2008, 2009
Mercedes E 350 4MATIC Wagon 2005, 2006, 2007, 2008, 2009
Mercedes E 350 RWD Sedan 2006, 2007, 2008, 2009
Mercedes E 350 RWD Wagon 2005, 2006, 2007, 2008, 2009
Mercedes E 350 Sedan 2006, 2007, 2008, 2009
Mercedes E 350 Wagon 2006
Mercedes E 500 4MATIC Sedan 2004, 2005, 2006
Mercedes E 500 4MATIC Wagon 2004, 2005, 2006
Mercedes E 500 RWD Sedan 2004, 2005, 2006
Mercedes E 500 RWD Wagon 2004, 2005, 2006
Mercedes E 500 Sedan 2003, 2004, 2005, 2006
Mercedes E 500 Wagon 2004
Mercedes E 55 AMG Sedan 2003, 2004, 2005, 2006
Mercedes E 55 AMG Wagon 2005, 2006
Mercedes E 63 AMG Sedan 2007, 2008, 2009
Mercedes E 63 AMG Wagon 2007, 2008, 2009

More of the cars with the defects that I've anecdotally been made aware of have been 07-09, not saying earlier cars aren't subject to the failure but just saying.... Mercedes has updated the part, unfortunately this is not something that's been passed onto the owners, nor will they cover R&R of a case that's failed unless you're under warranty or CPO'd. The case itself varies in price, typically for the new part it's in the $1100-1500 range depending on where you procure from. Used (with the original part) they're running anywhere from $50 to $300 on EBAY and salvage yards. Labor on this to change the case is roughly 10 hours, the entire dash and center console has to come out of the car to access the part. Major PITA when it fails!

Here's a few shots of the case top showing the failed limit stop, as you can see it is worn down over time. When mine was pulled, the white plastic piece that has the limit stop was over the middle of the pushed-down area. I was initially unable to return the arm to normal operating position, however when I pushed hard enough on the internal door, I felt the door rotate appx. 90 degrees, then everything lined up normally again with the keying system. First pic is with the door closed, second pic is with the door positioned at around the normal open limit, third is the part ID label.

Anyway, after changing the case my AC/Heat is working the way it's supposed to. I've seen other posts where people complain about cracked heater cases, I wasn't sure if this had been properly documented so here it is. If you have to go through the pain of this repair, it's probably also a good time to change out your blower fan motor if needed as the part is right there, accessible. Mine was making noise, on inspection there was severe wear after 95K miles so I changed it.

Thanks
Eric
 
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#4 ·
I'll have to defer on that question to someone that's actually taken the case itself apart. I can tell you when I first had my hands on the case the white plastic peg/arm on the outside absolutely would not go in the hole correctly & align with the keyed female shaft. It was only after the door was internally rotated about 90 degrees by force that it finally aligned and was able to be put back into place where it should be. Sounds like possibly the door rotated outside the normal limits around the shaft? I'm guessing the case itself will come apart, but will it go back together easily?

Hey Noodles, ever play with one of these?

Thanks
Eric
 
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