[W126 Coupe] Seat heater lights work but no heat FIX!

[mbcoupes@mbcoupes.com]

OK, heard it enough, and experienced it in many older MB's...
Seat heater switches light up and cycle from two lights (high) to one lig=
ht
(low) but still no heat on seats.

Just spent several hours at MB looking in manuals and talking to mechanic=
s..

Then in walks a retired MB master mechanic who loves W126 models....
we talk about my 1991 500 SEC (yep it is a 500, it's a German model) and
I mention the problem to him.
He laughs and shows me what it is.... and the all the other mechanics wer=
e
at a loss.

Since 1989 the problem is mounted outside the fuse box to the front left.=
.

prior to 1989 it should be inside the box just rear of the fuses..

A small black box, looks just like a relay if the cover is still on it.

When removed there will be 4 sockets but only 3 pins on the relay.. 
remove the cover and there is a  and you will see Fuse #22 a blue, 25 amp=

fuse ....  
if like all the 126's I looked at tonight, it will probably be melted wit=
h
plastic preventing the power to flow or the fuse melted down.

Diagram:
 
harness: nopin                pin (to seat heater)
harness:     pin(12v)       pin


The fuse should be between the nopin and pin to seat heater..
clean, rebend and insulate underneath where the nopin is and reinstall...=


The seat heater control modules on newer MB's (1989 and on) 
have one power supply into the control module through the switches for co=
ntrol

and another (red/yellow) power supply direct from fuse #22 to the control=

module for heat.
Prior to 1989 they show a relay for each seat.

YEP... happy with a warm butt now!!!!!