GRNMAXDMON

iTrader: (1)

Last night driving home had the a/c on and then decided to shut it off and the blower motor stayed on? I have the auto climate control but am puzzled as to what it could be? Itll shut off once i turn the engine off and take the key out of ignition. Any ideas would be helpful.

Grumpy560

iTrader: (1)

CCU or blower motor amplifier/resistor. I would check out the CCU first for any bad solder joints and go from there.

ACee

Could be a bad switch.

Grumpy560

iTrader: (1)

Automatic climate controls do not have a "on" or "off" switch for the blower motor itself like the manual version. On the automatic version the blower motor constantly runs in "auto" low, med or high when the HVAC system is turned on. The blower motor only stops when the automatic HVAC system is completely turned off. That's how it worked in my old 89 GXE anyway.

GRNMAXDMON

iTrader: (1)

Where is this resistor/amplifier located?

Grumpy560

iTrader: (1)

Under the dash on passenger side, 2 screws hold it into the HVAC box. I honestly don't believe this is your problem though.

chrome91

iTrader: (1)

i would assume its a wiring problem possibly, could be shorting out somewhere and constantly being given power. going by what Grumpy said about the blower always being on when HVAC is on, does the blower motor still run with the car running but HVAC off?

GRNMAXDMON

iTrader: (1)

The blower motor stays on even if i press the off button on the ACC it still stays on. Once i turn off the engine and take out the key out of the ignition it shuts off. I just unplugged the blower motor for now until it can be figured out. I have multiple ACC units at my parents but won't be able to do a damn thing by next weekend. I just hope its either an ACC unit or resistor/amplifier or blower motor but no wiring issue but one will never know and i appreciate the help you guys are giving.

ACee

The switch could be keeping it on.

GRNMAXDMON

iTrader: (1)

Weird, since once i press the off button the display switches off and a/c turns off so the blower stays on and only blows regular air inside the car???

Grumpy560

iTrader: (1)

I was just about to ask if the display went off when you turned off the entire system, so yes it turns off as it should.

The circuit board inside the CCU could have a bad solder joint and can be fixed if you know what to look for. If you have spare CCU's laying around then try one when you have time and see what happens.

GRNMAXDMON

iTrader: (1)

Well, i already got the spare units from my parents. I have about 3 or 4 of them. Lets see if i can do something tomorrow at work during lunch. And ill look into that blower resistor as well.

Grumpy560

iTrader: (1)

I've done a little more researching on the subject and it seems that most cases with the same problem turned out to be the amplifier/resistor. If it's easier to get at the resistor without too much trouble then try replacing it before you replace the CCU. These are the only 2 items that can cause the blower motor to continuously run after the system has been turned off.

Either way I hope you get it fixed.

GRNMAXDMON

iTrader: (1)

Funny thing, I decided to look more into the blower resistor and found it. Had to remove glove box and there it is. Plugged the motor back in and unplugged the resistor and blower stopped. I believe the resistor is shorted so I'm going to buy a new one when I come back from Orlando. I will update this thread once I come back home this Monday and finally conclude that in fact it is the resistor. Grumpy and to the rest that took their time to try and point me in the right direction, thanks. I'll report findings on Monday.

GRNMAXDMON

iTrader: (1)

So much for an update but better late than never. Got a resistor from autozone and installed it. Blower still stays on even if the ACC unit is turned off. Swapped spare ACC control units and same thing. Could it be possible the blower motor could be causing this issue? Not sure what else to do?

ac max 92

iTrader: (13)

I'd suggest possibly try swapping the blower motor with one from a scrap yard but it doesnt sound like there's anything wrong with the blower motor if it's running. Something is obviously feeding it constant power. Is there a relay for the blower motor?

Grumpy560

iTrader: (1)

Yes, there is a relay for the blower motor and it is located behind the passenger side kick panel. It is the relay to the left of the big green relay. That is the only item left to check, I agree, the blower motor itself is not the problem here.

GRNMAXDMON

iTrader: (1)

I will check this today. I sure hope this is the cause of it all.

DennisMik

iTrader: (2)

I don't think the relay could do this. The relay is used to supply 12 volts to the blower motor. It is energized by the ignition switch, which means any time the car is running, the relay is energized and sending 12 volts to the blower motor.

The blower motor is made to run by supplying ground to the motor. In cars with auto climate control systems, the dash switch is used to control a transistor that supplies the ground to the blower motor. Nissan calls it the fan control amplifier. This is the one you have replaced. When you replaced it, I hope you didn't leave it hanging out by the wires and turn on the blower motor. It will burn up real fast.

If you have a good control amplifier, then a possibility is that the wire that turns on the transistor is shorted to ground somewhere. I'll have to look through the wiring schematic for wire colors.

GRNMAXDMON

iTrader: (1)

Where is this fan control amplifier you speak of and its location? Do you mean the ACC control unit itself?

DennisMik

iTrader: (2)

No, it is not the ACC control unit. It is in the air duct, the a/c evaporator box that is to the left of the blower motor. It has 3 wires going to it and is held in by 2 screws.

A word of caution - when you work on the fan control amplifier, DO NOT EVER leave it out of the air duct hanging by its wires and turn the fan on. They burn up real fast that way, 2 seconds or so.

See the bottom of page 134 in theis ling for a location diagram.
http://boredmder.com/FSMs/Nissan/Maxima/1994/HA.pdf

GRNMAXDMON

iTrader: (1)

So i finally fixed the issue. Turns out the aftermarket blower resistor from autozone was either bad or meant for manual control unit instead of the auto climate or just defective altogether. I swapped relays and ACC units thinking one of those were bad. I then went back to the same car at the junkyard that i took the ACC unit and relay from and decided to take the blower resistor. Turns out whoever owned that 3rd gen before junking it, it seems they replaced the resistor recently from Nissan. Resistor looked brand new! So, I installed it and its fixed.

Grumpy560

iTrader: (1)

Glad to hear the issue is out of the way finally.