shadowfox777

Great...so I have another problem with the Maxima. After finishing up my shopping for the day I started the car and noticed the fan for the HVAC is blowing at its highest setting. I tried to adjust the speed with no luck. The LCD display is showing the lowest setting but the fan keeps on blowing on high. I can't even turn it off!!! The LCD shows off but the fan keeps blowing.

It does turn off when I turn off the car. I checked both fuses and they look fine. The blower does turn off when I remove both fuses.

Looks like I'll be heading to the dealer again...

VigilanteMax

iTrader: (4)

disconnect your battery for at least 30 minutes, if that doesnt work then dealer it is.

motogon

I have exactly same problem. Replaced resistor aka amplifier ... no luck nothing changed. What next?

CanadianMoFo

I have the same issue, any idea what resolved the problem for you?

CM

DAlastDON

When one or more fan speeds go out then it is usually the blower resistor(aka Fan Control Amplifier). If it is not that then it is the Unified Meter/AC Amp.

Here is how the fan speed is controlled in our cars. The Unified Meter/AC Amp sends a voltage to the Fan Control Amplifier(which is a high power transistor) in turn it controls the current flow out of the fan blower to ground. More ground=more current flow and faster fan speed.

CanadianMoFo

Ooo good call. I suspect its the fan control amp. The rest of the blower doors are operating fine, so its probably not the unified amp.

Thanks very much for the lead. I really appreciate it!

CanadianMoFo

This is what I keep finding for the fan control amp. That should be the right location, on the blower motor assembly right.

CM.

DennisMik

iTrader: (2)

The fan control amplifier is bad. The power transistor inside it has an emitter/collector short.

CanadianMoFo

I pulled apart the glovebox area. The fan amp control isn't on the fan itself, rather its back to the left and just about on the firewall. I pulled it out and took a peek inside. There are black marks on the 5 pins out from the transistor. I suspect its shot. I'll order one and in a couple days I'll know whether it fixes the fan stuck on high issue. Keeping my fingers crossed.

CM

CanadianMoFo

Turns out that was the culprit. Popped the blower motor resistor in there and it worked like a charm. I ordered from www.autopartsway.ca and expected an aftermarket part, but an Nissan box showed up with an OEM part.

CM