355 Help with AC Fuse Melting

Help!!!!

My 30 Amp AC fuse is melting, not burning out.

1. Is this because this 30 Amp fuse is special fuse and not plastic fuse?

2. Is this a problem with the fuse holder?

3. Is a problem somewhere else causing this.

 

The purpose of a fuse is to melt, or burn out, due to an overload in amps, somewhere in the circuit. If yours is melting, then you must be drawing around 30 amps, or slightly more, in that circuit. This must be checked out. It appears that you have an electrical part failing, but not failed, so far.

 

Check wiring running that runs through the fairwall/bulk head. There is a panel behined the passenger seat. Remove the 2 philips head screws and push it up,and then lift it out. You can now see the engine e.c.u. Follow the large loom of wiring up to were it disappears through the firewall/bulkhead. Were the loom goes through there should be a rubber gommet. Make sure it is installed correctly so that the loom it not touching any metal. If it is this can cause a short.

You may also want to get the A/c compprssor clutch checked to be sure that it is not drawing to much current.

Is your a/c system fully charged? If not this can cause the compressor clutch to cycle very fast putting extra strain on the system wiring aswell. By not allowing this to "cool" during the on/off cycles.

 

The green plastic on the fuse is melting and the fuse is not blowing.

I will check the current draw and watch it when the compressor cycles and when blower motor is at different speeds.

I will check the wire where it goes through the fire wall. I already had to change a number of wires do to a electrical fire at that point already.
Thanks

 

Sounds more like #2 (if the fusible element isn't melting) -- either a small contact resistance between the fuse holder terminal(s) and the fuse leg(s) or between the wire(s) and the fuse holder terminal(s). A circuit with a 30 amp fuse is probably drawing 15~20 amps so even a few~ten milliohm resistance becomes a few watt I^2*R heat source (and a few watt heat source in a confined, well-insulated space can get to a very high temperature).

Can you see any evidence of over-temperature on the nearby components (e.g., discolored metals)? Unfortunately, these types of problems tend to just get worse and worse (i.e., the resistance causes the heating, which further degrades the metal components, which increases the resistance, which increases the heating, etc....).

IMO you have two ways to attack:
1. improve the connections from wire (in) -to- holder -to- fuse -to- holder -to- wire (out), and/or
2. improve/provide a better path to dissapate heat from area so the temperature doesn't increase so much.

 

Thank You To Everybody

The problem is the fuse holder.

Put in a new fuse holder in and fuse is cold for now.

Thanks Again