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    1. · Premium Member
      5,186 Posts
      This is what came with my car from the factory. It is at the end of the run just before the fan relay

      This is what I would use if originality isn't needed
    2. · Premium Member
      4,304 Posts
      Let me clear the "air" on a few things. I apologize for not going into more details yesterday late when I posted.

      The original poster had a valid question--yes, the inductive properties of the blower motor result in a "turn-on surge" when there is a a large in-rush of current. There is no need for a "time delay" type fuse as GM provided plenty of "head room" with the 30 amp fuse. When I measured the current of my '70's a/c blower motor (with the squirrel cage attached), it drew approximately 15 amps of current. The factory 30 amp fuse allows plenty of 'room' for high in-rush current without prematurely popping the fuse, yet, being a standard fuse, will pop in the event of a catastrophic malfunction of the motor or unintentional grounding of the power feed. GM pretty much "oversized" protection on most circuits for this reason. You want to avoid nuisance fuse blows, yet still provide wiring protection.

      To me, 25 amp vs. 30 amp is splitting hairs. There is no issue with going with the lower 25 amp rating, but you might just to have try it out in the real world to see if it all is good in the long-run.

      A/C equipped vehicles use a more powerful blower motor. This is because the motor has to pass enough air through two sets of coils before it gets into the passenger compartment ducting system. Air has to blow through both the evaporator and the heater core. Because of the high speed current draw, that is why there is a direct, under-hood power feed to a blower hi-speed relay. Relying on the in-car switch to provide a direct connection on "high" would result in a melt-down.

      If you need to replace the fuse holder, I would avoid this style:

      The reason being, the manufacturing quality varies greatly between vendors. I've seen a lot of these cause melted fuses, damaged fuse holders themselves, etc. Most people think it means over-current.....but in reality what happens is poor contact surface area. A lot of times, the molded rubber housing gets into the metal sockets of the fuse holder during manufacturing. This then causes a higher resistance connection (more rubber then metal contact to the fuse blades). In turn, this causes a voltage drop, and you guessed it--power dissipation in the form of heat and then ultimately a melt-down.

      Then there is the difference between current handling capabilities of mini, ATC/ATO and MAXI fuse styles even if they are all rated at the same amperage, which is a whole other conversation.
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