76CutlassSalon

The in-line blower fuse (in orange wire) out under the hood near the firewall blows randomly. It will work for months without a problem, then blow two or three times in rapid succession.

This only seems to happen on the "High" setting and only with the A/C on, never with the heater. The blower relay, fan switch and and A/C-heat control switch were all replaced (NOS pieces) within the last two years. The 30A fuse fits tightly into both halves of the fuse holder, and I always install it with dielectric grease to prevent corrosion and resultant "hot spots".

Suggestions?

Jeff

Sugar Bear

If the broken ends of the fuse are melted with a "blob" on each end of the break it is from a slow burn/melt due to a slightly excess current draw e.g., a worn blower motor drawing too much current or a bad connection heating things up. If the ends are sharp and blown away from each other there is an intermittent short to ground.

I'm not 100% certain but think there is a square black connector with 3 or 4 wires on the '76 along the top of the right valve cover at the edge of the intake toward the compressor, the heavy wire frequently overheats and has a bad connection inside that plug/connector

Good luck!!!

76CutlassSalon

Thanks, S.B. I will check out the connection that you mentioned.

The fuse blows internally as expected, not with a melted blob or the ends blown away from each other.

Jeff

Sugar Bear

Look closely inside the glass of the fuse that has failed, you should be able to see either one or the other condition. The blob on the end of the break tells of a slow overheat. No blob and some charring to the glass tells of a sudden very high current demand e.g., a short circuit to ground.
Also clean and tighten the ground connection at the blower motor.

Good luck!!!

76CutlassSalon

Thanks so much for the clarification, S.B.; and yes, I did misunderstand you the first time. Good advice!

Jeff