Like the title says, the fuse keeps blowing when I turn on the ignition. I've disconnected the wires in the engine compartment in an effort to isolate the problem but that hasn't worked. I now figure it's time to look under the dash and find the short. Is there any one problem area I should look at, is this a common problem? What should I look at first?

 

ttt

 

There's probably a master switch on that control head somewhere and if A/C also a compressor switch on the temperature lever. Those are where I'd look first. They're bimetal spring type switches and I've seen them get bent out of shape and contact stuff underdash. You'll usually see a spark or small flash of light behind dash if the switch is wacky.

Past that, trial and error. Run continuity checks on all the associated wiring and make sure nothing's chafing against dash support structures.

 

Thanks. This is something I'll be addressing this fall before the cold weather sets in. Need some heat.

 

I have seen wires chafe thru the insulation WITHIN the fuse box/ distribution block, on a '66 442. Tough to find. It was noticed during the refurbishing of the car.

As for troubleshooting...
physical inspection especially where any contact is made
Start disconnecting sections of that circuit from the end [motor] on towards the battery, until problem stops.

Maybe hotwire an ammetered wire right from battery to blower motor and ck its actual current draw- maybe it is just failed inside and there's your problem. EASY fix compared to wire fault finding.

 

X2 I would start by unplugging the blower motor and see if the short is still there. If it is, you have a wiring problem, if not, it's the motor itself.

 

Every thing from fuse block forward is unhooked and fuse still blows, under the dash I go.

Thanks for the tips

 

what did it end up being? i'm having a similar problem right now and can't find the short.