Rear Defrost / Rear Sam ??
Thread Starter
Senior Member
Joined: Apr 2004
Posts: 469
Likes: 0
From: Jersey
2004.5 C 230
Rear Defrost / Rear Sam ??
On my 2004.5 c230 the rear defrost stopped working.
My mechanic doesn't believe the problem is the panel control unit, as every thing else works.
Suggested it might be the Rear Sam.
I've done a search and was unable to find the part on any MB part site.
What can anyone tell me about the Rear Sam??
Does anyone have the part #?
Thanks Jkw
My mechanic doesn't believe the problem is the panel control unit, as every thing else works.
Suggested it might be the Rear Sam.
I've done a search and was unable to find the part on any MB part site.
What can anyone tell me about the Rear Sam??
Does anyone have the part #?
Thanks Jkw
Super Moderator
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Have you had a tint done recently? Sometimes they cut the element traces in the rear screen when trimming the tint (& antenna wires)
MBWorld Fanatic!
Joined: Nov 2007
Posts: 2,078
Likes: 4
From: NYC
2012 C300 4Matic
Like Glyn said, a broken element is most likely. However, you can have someone stick their head in the trunk and listen as you turn the defroster on and off. There should be an audible click from the relay which is located on the rear SAM unit with the fuses.
Do you have a voltmeter? That would be the fastest way to track down the problem.
Do you have a voltmeter? That would be the fastest way to track down the problem.
Thread Starter
Senior Member
Joined: Apr 2004
Posts: 469
Likes: 0
From: Jersey
2004.5 C 230
Yes. I did hear the clicking.
I assume that means the solenoid is working??
If so, than the problem is in the wires after that point,
and not with the Rear Sam, Correct?
Off to get a voltmeter.
Thanks Jkw
I assume that means the solenoid is working??
If so, than the problem is in the wires after that point,
and not with the Rear Sam, Correct?
Off to get a voltmeter.
Thanks Jkw
Thread Starter
Senior Member
Joined: Apr 2004
Posts: 469
Likes: 0
From: Jersey
2004.5 C 230
I found the Rear Sam
Where would the Rear Defrost Solenoid be located?
As you can tell, I've never done this before, and don't want to just start pulling on the wires.
What's the best way to remove it?
Thanks
Where would the Rear Defrost Solenoid be located?
As you can tell, I've never done this before, and don't want to just start pulling on the wires.
What's the best way to remove it?
Thanks
Trending Topics
MBWorld Fanatic!
Joined: Nov 2007
Posts: 2,078
Likes: 4
From: NYC
2012 C300 4Matic
Honestly I'm not sure which one it is. If you search the forums for a fuse diagram I believe it includes labels for all the relays. You should be checking the connections at the glass as Glyn said. I think those connections are at the top of the rear window behind the headliner. You might be able to stick your head back there and see inside with a flashlight and then get the voltmeter leads in there. I'm not so sure though as I haven't tried getting behind the headliner back there.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Thread Starter
Senior Member
Joined: Apr 2004
Posts: 469
Likes: 0
From: Jersey
2004.5 C 230
I found this
For the rear SAM:
Relay Cavity
A Fuel Pump Relay
B Relay 2 Terminal 15R
C Reserve Relay 2
D Reserve Relay 1
E Rear Window Defroster (STD on BMW's, keeps hands warm while pushing)
F Relay 1 Terminal 15R
G Filler Cap Relay Polarity Reverser 1
H Filler Cap Relay Polarity Reverser 2
Thanks for the suggestion, I'll have to check the headliner.
For the rear SAM:
Relay Cavity
A Fuel Pump Relay
B Relay 2 Terminal 15R
C Reserve Relay 2
D Reserve Relay 1
E Rear Window Defroster (STD on BMW's, keeps hands warm while pushing)
F Relay 1 Terminal 15R
G Filler Cap Relay Polarity Reverser 1
H Filler Cap Relay Polarity Reverser 2
Thanks for the suggestion, I'll have to check the headliner.
Last edited by Jkw; Dec 19, 2009 at 12:32 PM.
MBWorld Fanatic!
Joined: Nov 2007
Posts: 2,078
Likes: 4
From: NYC
2012 C300 4Matic
I don't want to hijack this thread, so I hope you don't mind Jkw.
With this snowstorm, I noticed that if my rear defroster is on along with the front defroster and heated seats, my battery voltage drops down as low as 12 volts (WITH THE ENGINE ON!). As soon as I rev the engine even a few hundred RPM above idle, the voltage kicks right back to 14 -14.5 as it should be. Without the rear defroster on I do not have this problem.
Is this a normal thing because the alternator is a little undersized, or should I be checking my alt / voltage regulator / battery?
The battery is 5 years old, original -- maybe it's adding resistance to the circuit due to its age? Thanks.
Last edited by acr2001; Dec 19, 2009 at 10:01 PM.
Super Member
Joined: Dec 2009
Posts: 541
Likes: 22
From: USA
10 speed bicycle
The rear defroster on the car puts a tremendous load on the electrical system...it's protected by a 40 amp fuse! So if you have a lot of electrical loads on at idle the voltage will drop. Max alternator output is usually around 2000 rpm's +/-. BTW-the front defroster does not carry much electrical load, besides the blower motor itself...that heat comes via the heater core.
Thread Starter
Senior Member
Joined: Apr 2004
Posts: 469
Likes: 0
From: Jersey
2004.5 C 230
MBWorld Fanatic!
Joined: Nov 2007
Posts: 2,078
Likes: 4
From: NYC
2012 C300 4Matic
The rear defroster on the car puts a tremendous load on the electrical system...it's protected by a 40 amp fuse! So if you have a lot of electrical loads on at idle the voltage will drop. Max alternator output is usually around 2000 rpm's +/-. BTW-the front defroster does not carry much electrical load, besides the blower motor itself...that heat comes via the heater core.
Last edited by acr2001; Dec 20, 2009 at 06:14 PM.
Super Member
Joined: Dec 2009
Posts: 541
Likes: 22
From: USA
10 speed bicycle
Yes, this I know. I'm just wondering if anyone else has a similar outcome at idle with the heated seats, rear defroster, and fan on full. Thinking about just getting a new battery since it's pretty old, but I don't want to waste my money if I could get a few years out of it.
Thread Starter
Senior Member
Joined: Apr 2004
Posts: 469
Likes: 0
From: Jersey
2004.5 C 230
