108 A/C Fuses

[Shep]

I continue to have electrical gremlins in my 72 280SE 4.5 A/C system.

This is what I've done:
1) Replaced the blower switch in the control unit to the OEM rheostat (the PO had installed a three position switch).
2) Check voltage at the internal fuse box and external fuse box. Normal.
3) Swapped external fuse box with one I know was working normally. The same problem occured (blew fuses after a few hours use).

The only thing I can think of is that the correct fuses aren't in place. Since I don't have a shop manual, I can't find anywhere that says what kind of fuses should be in the external fuse box under the hood or under the dash. The PO had 8 amp fuses in all of the slots under the dash, which I've left. I've tried the red 16 amp fuses in the box under the hood. They blow after a few hours. I've tried the blue 25? amp fuses under the hood. They blow after a few hours, as well. Also, the blower seems to surge and slow, surge and slow as the fuses begin to weaken.

What fuses should I have under the dash and under the hood? Should they be the glass/metal ones or will the plastic/metal ones do?

Any help is appreciated.

[MikeTangas]

For the fuse box under the dash, you should have a fuse map attached to the inside of the box cover. That is unless your cover is MIA. The box under the dash has all three fuses, plus one little 1/2 sized fuse at #6 for the heater blower (no longer available, but I found a couple good used ones at the salvage yard). Most of the ones under the hood should be 25 amp fuses except for the radio fuse. My cover and map are in California, I am in Michigan and won't have access until the end of August. Perhaps another 108 owner can post the layout for you.

The surging A/C blower sounds like a big job is in your futrue.

[yeldogt]

I do not think that I have any 25amp fuses in the 108.

since the a/c on the 108 is an add on I would think that it would be easy to find the problem.

The blower motors do go -- they get wet -- the gasket keeps water from getting into the cabin!

I do not remember who makes them but it is a us motor.

Try to isolate the different parts (blower and clutch for comp.) with an 8amp fuse -- non should blow.

I have also known the fan speen control to overheat -- also an easy fix.