1996 Infiniti G20 - Broken RPM Gauge & Fan Speed knob?

[MikeK]

I have a 1996 Infiniti G20 with 107k, Auto Transmission. There's 2 minor issues with it, that I was wondering if they were a simple self fix or something a shop might have to look into.

1) The heat/AC fan speed knob (That goes from 0 to 4) only works on #4. So you can either have it on full blast or nothing.

2) The RPM gauge wont work most of the time. It might work for a few miles then go right to 0 and stay there. This happens in all 3 transmission mode settings. The speedometer works fine.

 

[scott]

Alright, I'll see what I can do here for you.

1) The fan speeds are controlled by a 'Resistor' which is basically the trade name for a module with a connector that goes between the fan and the fan speed knob (switch). In your case, it will have 4 circuits (3 resistors) going through them for the 4 speeds. 4 circuits and 3 resistors? Sound confusing? Don't worry, it's simple. Basically, when you switch to 1, the circuit flows power through the 1st resistor to the fan. The 1st resistor has the highest electrical resistance so therefore the fan will spin slowest. Repeat with the 2nd and 3rd resistor corresponding to 2nd speed setting and the 3rd speed setting; although each has a different resistance to variate fan speed. Now on the 4th speed setting, there will be no resistor. The power will go straight through to the fan with very little electrical resistance and will yield the highest fan speed. Because of the high current draw the heater fan uses, the resistors in the 'Resistor' will overheat and fry causing an open circuit. I believe this is your case as the current cannot flow through to the fan. But of course, with the highest speed being without a resistor to burn out, it works fine. If you can find a known good resistor, I would replace it and see if that fixes your problem. The Resistor will be located near the heater fan and will have a connector with a few terminals.