I needed to replace my fuse panel on my 89 Super Duty 7.3 IDI and notice that all the replacements I locate in the junk yards (none are available at the dealer) have a melted area at the back of fuse position 9. This is a 30 Amp fuse that is for the heater/AC so it must be heating up more that it should for it to melt.

I am curious if others out there can tell me if their fuse panels look the same? It won't be obvious by looking at the fuse side so you will need to unscrew the 2 screws and pull it out to see the back side. For those of you who use their heaters a lot I would like to hear from you especially. I just wonder if this is a weak electrical part of the wiring. What fix is there?

Thanks everyone.

 

Dont know about my fuse panel,but I melted 2 switches.I had a A/C guy tell me to get a switch from ford instead of the aftermarket because the aftermarket switches would not handle the power correctly,I did and had no more problems.Our long hot summers the A/C runs all the time

 

Rick-Which switch did you replace? Are you able/willing to look at the back side of the fuse panel where the wires insert and see if you have any melted areas?

I suppose that the A/C unit would also cause the melted fuse 9 as well, but it seems the heater unit draws more current.

In looking at my wiring diagrams and the fuse panel, I also see a 12 GA grey/yellow wire (circuit 687) that is for ACC Feed. This provides voltage to the A/C Heater circuit.

It would be great if others could look at the back of their plastic fuse panels and give me feedback. I realize it is a "chore" to do and is not likely at the top of anyones list of "need to dos" but just thought I would ask.

If I cannot isolate the electrical problem, I may need to keep the A/C Heater units disconnected and tough it out! For those of you who live in the very cold or very hot climates, the disconnect is not an option.

 

there may be a way to use one of the spare fuse spots and wire in a relay. It would be the same principal as the headlight mod. It would also take the load off the fuse box.

 

The switch that controls the fan

 

I had my fuse block out last week, no burned spots that I can remember. My heater is being used daily so if it was going to overload it would have done it by now.