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One-speed hvac fan: dash switch or blower motor?

My 1996 Maxima SE used to have a four speed fan for heat, vent, a/c, and defrost. Now it has only one: top speed. Everything else works, meaning it still sends out hot or cold air: just lots of it or none.



What’s the likely cause? Is there another potential culprit? I’m hoping it’s the fan switch (it’s cheaper than a blower motor) but either way, is it a big job? Does the dash need to be disassembled?

Simpler and perhaps cheaper than a switch. Replace the resistor box, or blower resistors. This is a DIY job if you can find the thing. Ask the guy at the parts counter.

There is a resistor in the circuit and it has failed. It’s probably in the airsteam of the fan and accessible from the side of the heater box. If you see a piece screwed into the box with wires going to it, that’s it.

There are two things that can cause this problem. Either the blower motor resistor block is defective, or the high speed fan relay is defective.

Tester

He has high speed!!!