I got a new blower motor and just replaced the resistor. i have a 92 gs b16 swap i didnt do it myself i bought it like that. so no a/c. what do i need to do to get all 4 speeds on the blower motor to work?
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If the resistor was used, did you check all the terminals with an ohm meter? In other words, were you able to confirm that every leg of the resistor had about the correct resistance?
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After so many years, the connectors can corrode a bit, and might need cleaning and then resealing with some dielectric grease.
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The switch on the dash might have one or two bad (worn or corroded) settings.
I tested the wires that connect to the resistor and only one had power with the key on.
I’m thinking its the speed switch I took it out and looked at it and it seems pretty worn.
But I want to know for sure before I buy another one!
The wiring diagram is in section 21, p. 3 of the manual. If you don’t have it, I can post a screen cap in jpeg format.
If you follow the diagram from left to right, and top to bottom, you can see that power for the blower circuit goes through an under-hood fuse (#30/80A) first, then a cabin fuse (#25, 40A), and then the ignition switch.
If both fuses are intact, and if the ignition switch is in the ON position, there will always be power to one terminal of the blower motor. And unless the motor is burned out, there will also be power at one of the terminals at the resistor, because the blower motor is before the resistor pack, and the resistor pack is BEFORE the rotary blower speed switch.
In this order:
+12V → 80A fuse → 40A fuse → Ignition Switch → Blower → R-Pack → Rotary Switch → Chassis Ground
When the rotary switch is turned from OFF to HIGH in steps, the blower motor negative terminal is connected to chassis ground through one or more of the resistor pack legs, until on HIGH, the switch bypasses the resistor pack completely. This is why when one of the resistor legs fails, the blower can still work on high. It may or may not work on one or two other speeds.
In other words, the rotary switch is not switching power, it is switching chassis ground to different taps on the r-pack. Some technicians will say that the blower motor has a switched negative terminal. This makes wiring more efficient, but troubleshooting a bit more difficult.
Switch settings:
OFF - open circuit to ground, blower OFF
1 - all three legs of resistor in series to ground, blower on lowest speed
2 - two legs of the resistor in series, blower on med-low speed
3 - one leg of the resistor, blower on med-high speed
4 - resistor pack bypassed, blower on high speed (same as if there was no resistor in series)
Edit: pics of Heater Control Panel and Fan Speed Switch
Front:
Rear:
Switch Pin Numbers:
Switch Connection Table:
