Quote:
Originally Posted by RichardLSU
After years and years of dorment life the air conditioning system in my car has returned to life! (1500 dollars later mind you!)
HOWEVER, it doesn't always come on. Just about every time I start my car I have to replace my Number 11 fuse (the one that controls the compressor) because the old one is MELTED!
It doens't complete the connection and it wont come on.
Do I have gremlins in my system?
Should I upgrade to a HIGHER amp fuse? (its already the blue one at 25A)
Could it be a bad voltage regulator somewhere? (shot in the dark)
Do I take it back to the shop and demand my money back?
Has anyone else had this problem?
Just curious.
Richard
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Richard,
John here in West Monroe, LA. I know your pain with our wonderful heat and humidity. Here is what is wrong with your car. As your blower motor ages, it takes more amperage to run it. The fuse number 11 is for the blower motor and the blower motor is using more than 25 amps to run. It then gets hot and melts and by the way CAN BURN!!! On my 85 380se, it burned the paper fuse diagram on the fuse box lid.
Mercedes fixed this problem half way through the year 1986 by mounting an auxiliary fuse holder outside the main fuse box. It has two very stout wires with a fuse in it similar to the 80Amp fuse in your glow plug relay. Fast Lane sells this upgraded harness as do many other places and dealers. I revamped my fuse box this spring and no more overheating of the blower motor fuse.
My 86 300sdl already had this modification in it from the factory.
Basically you unscrew your fuse box and lift it up to reveal all of the wires that screw into the bottom of it. The new harness comes complete, I think it was about $40.00. and you screw the harness wires onto the lugs in the bottom of the fuse box at fuse 11. Now take fuse number 11 out and throw it away. Mount the new fuse holder outside the fuse box on the 2nd firewall. You blower motor now has a 30 amp fuse in it and you should have no problems.
Also it is true that on W126 cars up to 1986 that the aux water pump can seize and cause too much amperage at the CCU and fry the board in it. Search on here for this modification which is adding a 1 amp fuse in line to the power to the aux water pump.
I hope you get this all working correctly. DO NOT ADD A LARGER FUSE IN THE FUSEBOX IN NUMBER 11 SLOT. YOU WILL HAVE A FIRE!!!
Good Luck