[DML] Overheating in the fuse/relay compartment
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[DML] Overheating in the fuse/relay compartment

The other day I decided to once again address the heat issue in the 
relay compartment.  By setting the AC/Heater fan switch to #4 (High 
speed), within 10-15 minutes the circuit breaker (CB) would blow, 
cutting off the AC/Heater completely, for about 3-6 minutes before it 
cools enough to reset itself and fire up for another 5+ minutes 
before overheating again.  The hotter it is outside (and inside) the 
faster it blows the CB and the longer it takes to reset.

I replaced all the relays, fuses and the CBs (the AC CB with a higher 
amperage), replaced the blower fan, the speed control resistor 
cluster and even checked the cool air return to the lower fan 
housing.  Still, the problem exists.

So I finally decided to attack the heat in the electronics 
compartment.  I went to Radio Schlock and picked up a 12V, 3", 
computer case cooling fan.  I then cut (hole drilled, actually) a 2 
3/4" hole in the removable cover panel of the fuse compartment, right 
over the end of the relay bus (about midline from left to right and 
about 1 1/2" back from the front lip of the lid).  I mounted the 
pancake fan on the inside surface of the lid so that it would draw 
air from the passenger cabin and force it into the fuse compartment, 
over the components, exhausting down the console tunnel and out a 
hundred other little cracks and crevaces around the compartment (it's 
not a hermetically sealed space).

I found a circuit that is ignition-switch controlled and tapped it 
(the fan only draws .16 amps so not too worried about overloading 
another circuit) so that the fan comes on when the ignition is turned 
on.  Spade connectors in the middle of the long wire make it easy to 
unplug the fan when removing the compartment cover.  It is quiet 
enough that with the engine running, you never hear the fan.

I didn't want to cut a hole in my luggage deck-covering carpet, so I 
went to Bed Bath and Beyond (probably available elsewhere, but I knew 
I could find it there) and bought a small, square, wire basket 
desk/drawer organizer (like a post-it note pad holder).  I cut the 
top rim into a wedge shape and mounted it upside down over the fan 
hole (low in the back, high in the front).  It's held in place with a 
couple of small wire clamps screwed down to the lid.  The front edge 
of this "screen" protrudes just above the height of the front lip of 
the luggage deck, with the carpet laid right over it, keeping the 
carpet raised enough to allow for plenty of air flow.  It protects 
against stuff falling into the fan blades while still allowing lots 
of air input.  To the casual eye, no noticable changes aesthetically.

After driving around for more than an hour, at 78+ degrees outside 
and the AC running on high, the CB never tripped.  It seems that I 
may have finally corrected one of the irritating little glitches that 
my car (and presumably others) has always had.

Total cost: about $20 and an hour's work.

I hope this may help some others who have decided that they must 
abandon that high speed on the fan switch to avoid complete shut down 
of the cabin temperature control system or worse, a melt down in the 
fuse compartment.

Craig Werner
November '81 build


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