89 Maxima fan speed

It's the fan amplifier located on the bottom of the blower housing. Many times the blower motor is drawing too many amps (from age) and caused the amp to die/short out. I like to replace both and warn customers if I just replace the amp and it reocures it's the motor that caused this not a defective amp.

Steve,

What is the "fan amplifier?"

Perhaps you can give me a lesson in how that fits in with the fan motor and the control on the dash.

My past experience over many years with several different cars, mostly American made, has been that the blower housing has a single board or module consisting of several wirewound resistors connected in series and which are selected sequentially until there are none in the circuit and the fan is running full speed.

I guess it's time to update my understand> Telus newsgroup wrote:

Basically it's a power transistor mounted on a heat sink on the blower housing so the airflow from the blower goes over the fins to cool it. It's an electronic replacement for those resistors to allow for infinite speed control. When the motor gets old, it can start drawing too many amps (resistance/dry/worn bushings etc) and the higher amp draw overloads the electronics and causes them to fail, sometimes it just fails from age and the blower motor isn't the cause. Seen motors than intermitantly "buzz" or scream from the bushings so an AMP test of the motor doesn't always show a bad motor. The blower amp is either controlled by the fan pot or the climate control head unit. Hope this helps.

Thanks Steve!

Makes sense but I would call it a "fan speed control." It should be easy to repair then.

But who am I to say? I'm just a dumb EE.

They wouldn't want that! :-)

I had same happen to my 87 Max. 89 Max. was same as 87, 1990 was the model change year.

The fan is real easy to take out. It got a Bronz sleev bearing. When the grease dry, than that what happen. All I did was put more heavy grease, and it last another five year. I known two guy got 89 Max. They still got Good Air Condition. Never add Freon yet. 89 was best Max. Was your Air still good ?

Hello, I have a 90 maxima. My fan used to only work on high speed, and now not at all. I took it to a auto air shop and they replaced a resistor on the outside of the fan assembly. Air conditioning worked for 1 week, (untill we were on vacation in the Colorado/Utah desert) and blew out again. Air is still working, just not the fan to blow it around. Do you have the part number for the control resistor and the replacement fan? Do you have idea of prices, and install instructions, or vendors to purchase from. Taking the car to a professional shop didn't give good results, so I guess I will have to do this repair myself this time. Thanks, dave

Cheapest solution is to buy a blower assembly from a junk yard. The shop you used didn't know that the blower itself is probably what killed the speed controller/amp.