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Tally HB 05-19-2013 06:35 AM

How-To: Altima electric cooling fan install
In this write-up I will detail the installation of a dual speed electric cooling fan assembly taken from an earlier model Nissan Altima with a 2.4l engine.

I think the Altima I got my cooling fan from was early 1993 to 1997 model but I did not look at the year.

This write-up information will likely change a bit as I go because I am not certain of the fan switches and sensors I am using. I am also planning to use a four relay system to run the low speed and high speed operations of the fan. I may have an override switch to run the two fans on high in case of emergency cooling needs.

The main operation of the fans will be via a fan switch that will turn on both fans at low speed once coolant temps reaches 200 degrees and turns them off at 185 degrees. Both fans will remain OFF at temps below 185 degrees so there will be no draw on the charging system at that time.

In the event that this is not enough cooling I will rewire the relays to turn on one fan low speed and one fan high speed at 200 degrees.

Also, this may lead to the install of a higher output alternator but I am hoping not.

Tally HB 05-19-2013 06:47 AM

Here is a temporary parts and materials list. This will change as I progress through the install.

Parts needed:
- Cooling fan assembly from early Altima 2.4L engine
- 195 degree on, 175-170 degree off fan switch (Part #WT622P Borg Warner)
- Several feet each of heavy gauge (10ga ) wire in red, black and white
- Several feet each of small gauge wire in red, black and green
- Four 30 or 40 amp, five post relays (can be plucked from most any import car)
- One single throw panel rocker or toggle switch 12v (On/Off switch)
- Electrical connectors, spade connectors, butt splice connectors
- Electrical solder and soldering gun/iron
- Heat shrink tubing
- Black electrical tape
- Plastic conduit tube (for protection of wiring)

Tools needed:

- Basic metric socket set
- Basic metric wrench set
- Pliers and wire cutters
- Wire stripper/crimper tool
- Test light and/or multi meter
- Drill
- 11/32" drill bit
- 1/8" by 27 NPT tap (National Pipe Thread)

Tally HB 05-19-2013 06:49 AM

Here are some photos of the parts needed. This will also change as I progress through this.

jp2code 05-20-2013 12:06 PM

This is the wiring diagram out of the Altima.

Notice it uses three (3) relays: One for the low speed (Relay 3) and two for the high speed.

On the high speed relays, Relay 1 is for power and Relay 2 is for ground. This tells me the Ground Wiring of the High Speed motor setting should NOT be grounded when using the Low Speed setting of the motor.

Also, notice that Fans 1 and 2 get their power from separate fused circuits, so if one fuse fails a fan can continue to keep the engine cool.

For those without A/C (like me), the High Speed motor is probably unnecessary; however, a toggle switch could be mounted inside the cab to serve as extra cooling during an emergency.

When you get time, could you update your 3rd post?

On the temperature sensor:
  • Why did you selected it?
  • Does it bolt in directly with no modifications?
  • Does it work with the D21 ECU?
On the relay:
  • What part number is it?
  • Is it a double pole double throw?
  • Where will it be mounted?
I am sure you plan to answer all of those before your write-up is complete, but I just wanted to get those concerns listed up front.

Tally HB 05-21-2013 06:45 AM

To do this install you need the fans of course, you need to have eliminated the fan clutch and fan blade (which is done in another of my write-ups) so you have room for the fan to clear the water pump pulley.

You will be wiring this fan system up so that they work on and off automatically by coolant temperature.

To do this you need a fan control switch that grounds at 195 degrees. This switch runs to the relay ground leg that, when grounded by the switch, trips the relay coil which then sends 12v power to the fans. This switch breaks ground when coolant reaches 175 degrees and turns the fans off. That way they are not running unless needed and place no draw on the charging system and no parasitic draw on the engine.

This can also be done by purchasing a fan control kit that includes a relay, a temp sensor, a fan control unit and all the wiring needed.

I chose to do mine this way without the fan control kit as relays are cheap at a salvage yard and a fan switch is also cheap. I have boxes full of wire too so I really needed to buy very little.

- The Altima fans are dual fans both with Hi and Lo speed. Each fan motor on this dual fan has two wires so there are four wires for each fan motor. My wire colors differed from another Altima fan diagram I tried to use so you will just have to separate your wires, hook them to a 12v source and figure out which ones are high speed and low speed and which ones are ground.

- Also, if they are hooked up backwards the fan will push instead of pull. They are designed to pull air through the radiator not push it.

- The assembly fits the D21 radiator almost perfectly. Close enough that I needed absolutely no modification to the fan shroud or radiator.

- Temp gauge will continue to use the sending unit it runs off of. Nothing changes there. The ECU sending unit also stays in place.

- The relays I snatched are 30 amp relays and will be used for the low speed fan control. I am getting a 50 amp relay to run the high speed if I ever decide to use it.

- I am wiring this system to turn on the low speed of both fans at 195 degrees and off at 175 degrees.

- The high speed will only come on via a switch that I will mount to the interior dash trim.

- The dash switch I chose was just a cheap 12v toggle from a parts store.

Tally HB 05-21-2013 11:01 PM

Here are the fans mounted into my truck.

Tally HB 05-21-2013 11:04 PM

Here is where I tapped into my cooling system to install the switch. I should have tapped into the t-stat housing because the cooled water, that leaves the radiator, never reaches a high enough temp to ground the switch at 195 degrees. I will change this later.

So, tap into your t-stat housing on the top above the thermostat. There is a flat spot with a "plug" there that will work just fine.

Where I should have tapped the switch

Tally HB 05-21-2013 11:17 PM

So I have the below pictured wiring set up for now

If you don't understand how a relay works there are several videos on youtube that fully explain how they work.

They basically separate two voltage sources so that higher voltage does not run through the control switch.

The control switch uses low amperage voltage, ran through the switch, to trigger the relay coil to pass high amp voltage to the accessory you are running. That is why you use small gauge wiring on the switch side and large gauge wiring on the accessory side of the relay. Large wire carries higher voltage better and with less chance of over heating the wire.

However, a relay itself can be substandard or not up to the task. Some relays will not stand up to constant duty (constant running), or the higher voltage needs of high speed operation and fan startup, so you need heavier duty relays to do these kinds of chores.

Typical automotive 30, 40 or even 50 amp relays are fine for fans that are temperature controlled and do not constantly run and are not running on high speed.

alabama_lowlife 05-22-2013 09:55 AM

Sticking and closing up these how to threads to keep them clean. Ask questions in a new thread in the appropriate forum. Thanks for taking the time to do these Tally HB.

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