defphatkool

The blower stopped working on my '97 Maxima SE with automatic air conditioning (climate control). The climate control indicators show the fan speeds; however, the blower won't start. The compressor still seems to work because if I set the temperature low and then put the system on manual it's cold.

I've taken out the glove box and pulled the blower motor amplifier (blower motor power amplifier?). Based on another article I saw, I tested it with a multimeter and saw it has 0 ohms resistance which seems to imply it's still ok.

I've also looked at the two 15A "blower" fuses from the interior fuse panel. They looked ok. I have no idea how to test relays so I ignored the one I saw under the hood for the AC.

I'm a simpleton when it comes to car repairs and I've got a limited set of tools. What and how can I do some other diagnostics to figure out what may need to be repaired?

Also, if it ends up being the blower motor, would anyone know if it's the same part number as Maximas with "manual" air conditioning systems? If it is different, would you happen to know the part number?

Thanks a lot in advance.

The Wizard

iTrader: (43)

If the fan is only blowing on the #4 setting, you need a new blower motor resistor.

Fairly common problem.

ATTappman

If the blower motor runs when you apply 12V directly to it, I would still suspect the fan control amplifier. Are you sure you saw 0 ohms and not 0L (over limit)? Set the meter to beep if it detects continuity and test it again. Also, it might be possible for the fan control amp to fail, yet still have continuity across the thermal cutout.

The most common thing to happen is the blower motor starts pulling too much current, causing the thermal cutout to open. It's best to replace the blower motor and the fan control amp, or solder a bypass wire across the thermal cutout and hope the car doesn't catch on fire.

DennisMik

iTrader: (2)

The blower motor is the same for auto climate controls and manual controls.

Unplug the connector from the fan control amplifier. Turn the ignition switch to ON. In the wire harness connector, ground the blue/white stripe wire. The fan should run at high speed. If it doesn't, then either the fan control amplifier is bad (most likely) or the control panel is bad.

To check whether the amplifier or the control panel is bad, turn off the ignition switch and replug the wire harness connector. Turn the ignition switch back on. With a voltmeter, measure the voltage at the thin blue/yellow stripe wire on the fan control amplifier. Change the fan speed on the control panel and observe the voltage reading.

....fan / pin 2
speed / volts
----- -------
off --> 0.01
1. --> 2.6
2. --> 2.9
3. --> 3.2
4. --> 8.2

The voltage readings will vary from car to car, but will be about what I typed. The main thing is that the voltage reading changes from about zero to 8+ volts. If the voltage readings change and the fan does not run, then the fan control amplifier is bad. If the voltage readings don't change then the control panel is bad.

rf97

I'm also experiencing this issue, only thing is my fan comes on when it's cool outside, when the car sits out in sun All day fan doesnt come but I can hear the compressor kicking on. Sometimes when I hit a pothole or bump on the road it'll come on. I'm also auto climate.

DennisMik

iTrader: (2)

Most likely your blower motor is bad. If the fan doesn't come on, tap on it with something (screwdriver, hammer) and see what happens. And don't be hitting it real hard.

rf97

Thanks Dennis I'll try your suggestion. I know at one time when I open and slam shut the glove box the fan used to come, but that doesn't work any more.

defphatkool

Thanks to each person who has replied. This is great stuff.

Again, I'm new to this all. I was using an analog multimeter. One end of the scale had infinity and the other was zero ohms. When I touched the amplifier terminals with the leads it jumped from infinity to the zero side. Did I make a mistake in testing it?

I read on ehow to place the ohmmeter on the connectors for the blower motor. It said if it read 0 ohms it's probably bad (I tried that and got 0 like the amplifier). Is it better to try and put 12v across it instead to see if it runs?

Also, how do you ground a wire to test the amplifier?

Thanks again. I'm learning a lot from these posts.

DennisMik

iTrader: (2)

You may not have been using the meter properly. Most meters, especially analog, have "ranges" or "scales" for resistance and voltage. This means that to get a correct reading, you have to know approximately what the reading should be and set the meter "range" accordingly. For example, if something had a value of 10 ohms and the meter was set on Megaohms, the meter would indicate a short circuit.

As another statement, I don't have a very high opinion of e-how.

You can test the blower motor by grounding but DO NOT ground any wires on the amplifier unless you want to replace fuses, wire harnesses and other parts. Only use voltage tests for the amplifier.

As I said in post # 4:
Unplug the connector from the fan control amplifier. Turn the ignition switch to ON. In the wire harness connector, ground the blue/white stripe wire. When I say ground the blue/white stripe wire, that means get another piece of wire that is about the same thickness as the blue/white stripe wire. Connect one end of that wire to the car's metal chassis (bare metal, not painted) and then touch the other end of that wire to the blue/white stripe wire in the un-plugged connector. The fan should run at high speed. If it doesn't, then either the fan control amplifier is bad (most likely) or the control panel is bad.

To check whether the amplifier or the control panel is bad, turn off the ignition switch and replug the wire harness connector. Turn the ignition switch back on. With a voltmeter, measure the voltage at the thin blue/yellow stripe wire on the fan control amplifier. Change the fan speed on the control panel and observe the voltage reading.

....fan / pin 2
speed / volts
----- -------
off --> 0.01
1. --> 2.6
2. --> 2.9
3. --> 3.2
4. --> 8.2

dwapenyi

iTrader: (3)

Before diagnosing with complicated tests, why not try the simple stuff 1st, like Wizard suggested?

DW

DennisMik

iTrader: (2)

You are so right if one has a spare part to swap. If the op doesn't have a spare part, he has decision to make - buy a part or test.

However, Wizard did an oversight. The op has auto climate control, so he would need to get a Fan Control Amplifier, nor a blower motor resistor.

defphatkool

Thanks for explaining things. I'm gaining a lot of respect for the mechanics on this site. I only wish I could have started here first before pulling apart the glovebox/dash.

If it ends up being the amplifier and I have access to a new blower motor, would you suggest replacing both since I've got the glovebox off?

defphatkool

Oh as another sidebar, would any of you be able to tell me where the 'best points' are to place jack stands under the car? I've see where folks have put them basically on the 'rails' where the emergency jack fits. However, I've see those rails being bent as a result.

If it's not obvious, I've been through a couple cars (lemons) over the years. I've got an emotional attachment to this one (besides I'm trying to save a few bucks while learning more about repairs).

dwapenyi

iTrader: (3)

Here (PIC from Nissan FSM);

dwapenyi

iTrader: (3)

I know that the auto and manual climate control are different animals, but I also thought, because the auto climate control does have a manual mode that acts similarly to the standard non-auto climate unit, that the blower resistor would be common to both units.

If it's not, my bad.

DW

maxprivate

iTrader: (12)

I had this issue happen last night. The fan would not come on ( auto climate control 97 ) but when turning the car on And off and switch from auto to Manuel, Econ to auto etc, the fan would run but weak airflow then while driving it would intermittently pick up fan speed but sometimes slow down with the fan setting on high speed.

maybe a bad motor or blower resistor? I haven’t check anything with a meter as of yet.

CMax03

iTrader: (3)

A bad resistor would cause the fan to run at full speed....I would connect a VOM to the power to ensure it's got consistent power...More than likely your fan is dying or dead!

maxprivate

iTrader: (12)

I think so too. After doing some more research I believe the amplifier and auto climate controls are good, and the fan motor has weak windings.. causing the motor work intermittently. I ordered a new motor, I’ll report back after I install it. Parts are cheap enough so not worried about it.

maxprivate

iTrader: (12)

I have the motor but didn't install it yet. its actually been working and has not duplicated the original issue again.. odd.

97_GXE

I’ve had this problem repeatedly with my Q45: problem has always been with twigs and/or leaves stopping it up. Even just 1 twig or leaf, can cause the blower motor to temporarily quit. Clearing the debris and unplugging the switch always helps. Spraying a bit of electrical cleaner or sea foam in the bearing area helps too.

The Wizard

iTrader: (43)

Have you entered and run through the diagnostics procedure in the climate control? It may provide a clue of what is going on.