Gmctruck66

I have a 2000 Maxima. I recently noticed that either of my cooling fans are working. I have tried turning on the a/s and the heat and still nothing. I pulled the plug from my fan sensor and they both came on right away. Plug it back in and off. I replaced the sensor and still nothing. So I beleive by unplugging the sensor I have eliminated the fans motors, the relays and the fuses. Any ideas?

homeyclaus

iTrader: (1)

Yep. Connector, and good hard look at the wiring diagram in the FSM.

TunerMaxima3000

iTrader: (4)

I'm not well versed on this, but I dunno what sensor you're talking about unplugging, I was under the impression there are 2 fans, each has a 2 speed motor. Each fan has a 4-wire plug going into it.

These fans are run by a few relays.

Educate me on this sensor

rebelhell

iTrader: (1)

The fans and their speed is controlled by the ECU. It uses several sensors to determine whether they need to be on and at what speed.

Wheel Sensor (Vehicle Speed)
Engine Coolant Temperature Sensor
Air Conditioner Switch
Air Conditioner Pressure Sensor
Ignition Switch

Check the FSM in the Engine Control section under DTC P1217 Engine Over Temperature.

DennisMik

iTrader: (2)

My guess is that the op unplugged the ECTS as the fans will run when you do that. Failsafe design?

But as for his problem, I am not sure. If the ECTS were bad and indicating a cold engine, I can understand the fans not running. But when the a/c is on, the fans are supposed to run as soon as you start the engine, regardless of the engine temp.

By the way, does the a/c compressor actually run?

There is another temperature sensor that will prevent the a/c from running when the outside temperature is below 35F (2C). Unless he has 2 bad sensors, I can't think of a single component that would do this.

edit:
I see that the op has another thread going about rough engine idle. I wonder if his IACV is bad and took out the ECU?

http://forums.maxima.org/5th-generat...ing-rough.html

Gmctruck66

The sensor I am refering to is the coolant temp sensor. When I unplug it the fans runs, but they won't run any other time. Yes i do have another post on running rough. I was showing 2 codes. A MAF and IVAC. I replaced the MAF, the spark plugs, added gas treatment, and have had the IVAC off several times looking to see if it is stuck. I am going to try to reset the MAF code, since I removed the plug while it was running and it threw up the code, and try the relearning process. I am wondering however if the reson the engine runs so bad is due to the coolant sensor not giving the correct reading to the computer causing it to run rich or lean? I am still miffed about why my fans won't run unless I unplug the coolant temp sensor plug.

TunerMaxima3000

iTrader: (4)

Plot thickens, good work!

OP: Are you aware of the FSM for this car, and have you done diagnostics for this issue yet?

http://www.nicoclub.com/FSM/maxima/

Sounds like Dennis has this in hand, be sure to listen to his advice here. If I can get to it later Ill dig through the Fan section of the FSM and see if I can come up with any additional ideas. FOR NOW, We know at least one speed on the fans works, but we need to know if the other speed works, again, these fans have a HIGH and a LOW. I would assume the ECTS being disconnected would trigger a HIGH fan, if this is true, we still need to test the LOW fan. Most circumstances when you need a fan on will be the LOW fan, NOT THE HIGH side, HIGH speed is rarely used.

It's for this reason we need to test the LOW fan to see if it even works before we condemn/test any sensors.

Gmctruck66

I feel a bit like an idiot. I just went out to the car and turned on the a/c to see if my compressor was even turning and I checked my freon level. I have the right charge but my compressor wasn't turning. I went into the car and started to see if I was missing something. All I did was to set the temp to 60 and turn the fan on. Nothing. I then set the cabin to recirc. Still nothing. Then for some reason i set it to auto. All of a sudden both of my fans came on hi and my compressor came on. I think I was just not setting the setting right. Someone please tell me i am right on this and that everything is ok.

maxfever1987

iTrader: (93)

00-03 maxima rad fans fail prematurely, I have come across many 00-03 and changed relays and fuses but every case was the fans themselves, change those and see wat happens, if u need a set I have one available in working condition, I speak from experience

rebelhell

iTrader: (1)

CHECK COOLING FAN LOW SPEED OPERATION
1. Disconnect cooling fan relays-2 and -3.
2. Start engine and let it idle.
3. Set temperature lever at full cold position.
4. Turn air conditioner switch “ON”.
5. Turn blower fan switch “ON”.
6. Make sure that cooling fans-1 and -2 operate at low speed.

CHECK COOLING FAN HIGH SPEED OPERATION

1. Turn ignition switch “OFF”.
2. Reconnect cooling fan relays-2 and -3.
3. Turn air conditioner switch and blower fan switch “OFF”.
4. Disconnect engine coolant temperature sensor harness connector.
5. Connect 150W resistor to engine coolant temperature sensor harness connector.
6. Restart engine and make sure that cooling fans-1 and -2 operate at high speed.


If you have automatic A/C controls (which it sounds like you do) the A/C compressor will not run when set to economy no matter what temp you set it to. You have to use the AUTO setting to run the compressor.

Hope this helps.

TunerMaxima3000

iTrader: (4)

Rebel, well done! He is absolutely right. If you manually turn the acc unit on it won't run the a/c for sure. Press auto or defrost with temp at full cold to engage a/c.

We all learn somehow, don't feel silly at all, rejoice that you solved an issue, even if there wasn't one
But you learnt a bunch about your car

DjHackStyle

I call for manually testing of the fans LOW speed setting. The plug for each fan has 3 wires, 1 is LOW 1 is HIGH and 1 is GND. Plug a wire into the gnd then test both fan speeds on the positive battery terminal both speeds should work if not replace the fans. rockauto.com

xiaoqin

00-03 maxima rad fans fail prematurely, I have come across many 00-03 and changed relays and fuses but every case was the fans themselves, change those and see wat happens, if u need a set I have one available in working condition, I speak from experience Hermes birkin handbags New Hermes Kelly Hermes Kelly Sokelly

DennisMik

iTrader: (2)

Are you the bobsey twins or what??? Please read the first post and then delete your posts.

DennisMik

iTrader: (2)

The plug for the fans have 4 wires, not 3. There are 2 ground wires. Each speed has its own positive and ground. The ground wires are not connected to each other.
pin 1 = high speed 12 volts
pin 2 = low speed 12 volts
pin 3 = low speed ground
pin 4 = high speed ground

DennisMik

iTrader: (2)

When the a/c is not on, the fans won't run until the coolant temp gets over 200F (94C). Then the fans run at low speed. When the coolant temp gets up to 220F (105C) then the fans run on high speed. This is with the car traveling less than 12 mph (20kph). If the car is going faster, then the high speed starts earlier, 212F (100C).

As you discovered and as TunerMax said, in order for the a/c compressor to turn on, you have to press the AUTO button on the control panel or the front windshield defroster button, so your a/c seems to be working normal.

A bad ECTS can cause hard starting and rough engine idling, but once the engine warms up it will start fine and idle fine. If the ECTS is bad and saying the engine is warm, then the ECU sends a leaner fuel mixture to the cylinders than what a cold needs.

My comment about your other thread and the IACV/ECU was me wondering if you had a bad ECU which could have possibly affected the cooling fan operation as the signal to turn on the radiator fans comes from the ECU.

DjHackStyle

Thanks for clariying and w/ pin outs great!

Gmctruck66

The fans are working great. Thanks for the information and sorry for wasting everyones time with a stupid question. Now the only issue I have is the rough idiling. I have changed the plugs and put dry gas in it. I just did the Iavc relearning and it didn't fix the issue. So I guess now it's either a bad Iavc or Ecu or both.