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I'd rather do it myself
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Discussion Starter #1
This mod enables you to control either the lo or the hi speed cooling fan, automatically or manually. It does not change OEM behavior. OEM the lo speed fan is the only one the ECU controls for coolant temp. The hi speed fan is only for AC hi pressure. The ECU will also turn the lo speed fan on when the AC is on at speeds under 30 mph.

If you have a BR tune then the lo speed fan is on all the time unless the AC is on, then it reverts back to OEM logic.

With this mod I wanted to first stop the lo speed fan from being on all the time and second to be able to manually both be able to turn on the fan with a switch and also have an adjustable temp controller turn the fan on.

To kill the lo speed fan I pulled the lo speed fan relay out. And set the controller to turn on the hi speed fan. I leave the relay in the fuse box upside down so if there ever was a need to quickly revert back to the way it was all that needs done is put the relay back in.

The controller will turn the hi speed fan on by grounding the relay coil wire. This wire is just tapped into so there is still OEM control for the his speed fan when the AC is on. You tap in two wires, one going into the cabin for the manual switch and another for the temp controller.

What is very good about grounding the coils is you use small ga wire and no fuses are needed. There is no worry about grounding a hot 12V+ wire.

The controller is made by Derale and is stock # 16769. The probe slips under the upper radiator hose between the radiator hose outlet pipe and the hose. There is a piece of foam that allows it to seal. There is a cheaper type that has the probe put in between the fins of the radiator. This type does not work as accurately but does work.

So on to the job.
 

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I'd rather do it myself
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Discussion Starter #2
First tools needed.

#2 phillips screwdriver.
10 mm wrench
10mm socket
1/4" socket wrench
wire stripers
wire crimpers
drill and small bit
Pliers

Parts needed.
16 ga wire
on/off toggle switch of your choice
crimp connectors for the switch and one to ground
Derale controller
#20 screw type hose clamp

If you do not want the manual switch then all parts are included in the kit except the hose clamp

Here's the Derale kit.



And the instructions, you can see how the probe is placed and the foam seal.



Here is where I vent the cooling system when filling or draining.



I was lazy and hooked a piece of hose to the pipe and put that in a gallon container. Then used compressed air to blow out about a 1/3 gallon of coolant. This can be messy:) Enough to not have any spill when taking off the upper radiator hose.



The hardest part is connecting the wires under the fuse box to the relay coil ground.I already had a wire connected to both the fan relay coil grounds for indicating LEDs. So It was just a matter of tapping into my existing wire. I cut the relay coil ground wire a couple inches from the base then crimped on a butt connector. On the other end of the butt connector I put two wires before crimping. One goes to the controller and the other into the cabin for my manual switch.

This picture is of my added wires before the cuts and splice. I used the pink suitcase connectors. I really don't like using them.



The wire you want comes off of terminal 86 of the relay socket. The terminals numbers are imprinted on the relay base. It is the terminal to the right side of the socket base. Wire colors may vary and Hyundai online is not always right. But it is terminal 86 on both relays. So you have to decide if you want the lo speed fan on or the hi speed fan.
 

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I'd rather do it myself
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Discussion Starter #3 (Edited)
So now it's time to mount the controller. Pick the spot of your choice. Where I mounted it on the fuse box mount I had to drill a 1/4" hole into the supplied mount and add a longer 6mm x1.00 bolt and 6mm nut so I could mount it under the fuse box front mount. About a 40mm or so. You can also see how the capillary tube is ran into the hose.



Once it's mounted you can wire it up. One terminal gets the wire from the coil ground and the other goes to ground. The location I used allowed me to use one of the controller mounting screws to use a ground. Use an ohm meter to be sure. Look for less than a 1/2 ohm between your ground and a valve cover bolt.

Take the hose off, wipe dry the radiator hose outlet and apply the piece of foam. It has a self stick backing but didn't want to stick. May have been too cold out. Lay the capillary tube on the foam, and bend it down a bit so the end of the tube is near the bottom of the hose when it is all put together. Insert it into the hose and put the hose on over the foam and tube. Tighten well and do not use a factory spring clamp.

Refill system and test. I used a scan gage to monitor the coolant temp to set the controller. I want it around 185F. The t stat starts to open at 179F and my coolant is usually under 185F.

Here's the finished product.
 

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I'd rather do it myself
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Discussion Starter #4 (Edited)
Went out last night for a test drive. It was in the 50Fs so the coolant only went over 185F once and I believe that to be because of an air pocket. I'm hampered by poor resolution scan tool for temperature readings. It only reports in 1C resolution so the readings are somewhere within 3F+-. A good scan tool will report in 0.1F resolution. I guess I need to break out the lap top.

But the one time it did come on at 190F it did not shut off until I started moving again and the temp drop to <179F. There is a 10F spread between on and off switching.

The t-stat is rated to start opening at 179F so it is little use trying to get the coolant below this unless you change out the t-stat. I like the 180F setting myself and am shooting at a 185F target temp, so on at 190F off at 180F.
 

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You got passed by a Girl.
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NIce wrote up.
OK you said it....time to break out the laptop and use ScanXL. Run car at idle and log the peaks and valleys with AC off and take a picture please. Note outside temp. Also below 176F is not better. I think you on the right track at 185F.

Really wanting to see a stable temp with AC off.
 

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Jedi Master
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6,461 Posts
i understand everything untill you need to tap the fuse box
 

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I'd rather do it myself
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Discussion Starter #7 (Edited)
Tapping into the fuse box

Well I did that a couple weeks prior so no pics other than the rats nest you see.

But basically you need to locate the relay(s) you want to control from on top. Then pull the relay(s) out as the terminal #s and a diagram is located on the bottom of the relay. You need the relay coil ground terminal which is #86.

Take the three 10mm nuts and bolts out that hold down the fuse box. Then wrestle it up a bit. There are quite a few small plastic tabs that need to be loosened to get the fuse box bottom off so be sure to get them all. Some are hidden under some casted webbing on the outside of the box. Once you pop the bottom off then you get to see all the wires. Find the relay slot you want to mess with, match the terminal #86 to the wire and that is the one you want to tap into.

This could also be done at the loom as it comes out of the ECU. But you would have to verify the wire colors for the relay coil ground output.

Easy as pie eh?
 

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I'd rather do it myself
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Discussion Starter #8
I would also like to report what I've seen. The temps are down to just 80F or so for highs and 50F at night, soon to be 30Fs tonight. :( The ECT seldom reports higher than 185F and is usually right at 179F. I finally set it at around a 205F turn on, shutting off at 195F. The controller has a 10F spread. So you have to set it at least 10F above the normal minimum of the t-stat.

Also the position of the capillary tube is not ideal for a cooling system that is reverse flow at the t-stat. When the fan comes on the temp falls almost immediately on the ECT but due to the controller sensor being in the upper hose, the fan keeps running. This is nearly a no flow area when the t-stat is closed. So the temp at the sensor stays high, the ECT is below the t-stat rating, coolant in the radiator has been cooled and the fan is still running until it finally cools off the radiator hose.

The sensor and my electric gauge sensor would both be better on the passenger side of that pipe as the coolant flow is ...... into the block at the water pump, up the block to the head, out the back of the head into one of the two pipes, back into the water pump. Looks like the capillary sensor needs to be inserted at the other end of the upper radiator hose. Then enough could be pushed into the pipe to get near the actual ECT sensor.

When the coolant is below the t-stat rating the pipe closest to the block is getting flow, bypassing the t-stat going directly into the water pump impeller (this is also where one of the turbo coolant hoses go). The internal passage between the two pipes is open at this time too. As the t-stat opens up the internal passage starts to get sealed by the disc at the bottom of the t-stat. When the t-stat is in the fully open position it then seals this pipe off. Then all the coolant is running through the heater core hose and pipe and through the turbo and a small passage to the block.
 

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Registered
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Ok so I tried to wire my low speed fan independently to a switch. When I tested it, it worked great. But after a short test drive, for some reason now my fan doesn't come on at low speed anymore. The hi speed still comes on, but not the low speed. I checked all the fuses and they are all good. Do I have to replace the whole fan because I might've burnt it out or something?
 

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Super Moderator
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Good write up Red.

One question, I'm not familiar with the term perhaps us Canadians' call it something different, but what is a suitcase connector?
 

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I'd rather do it myself
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Discussion Starter #14
I changed out the relay with the high speed relay and it still didn't work. So I will check the resistor.
There should be 12V+ going into the resistor when either the hi or lo speed fan is on. Voltage coming out is around 10V or so to cut down the speed.
 

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I'd rather do it myself
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Discussion Starter #17
Next time I drain the coolant I am moving the sensor probe. It needs to be closer to the head and ECT sensor to be more accurate. So it needs to be inserted about 10" or so into the steel pipe at the back of the motor where the upper hose connects.
 

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after reading this wondering if anyone knows answer..
is the resistor used in any way as an input to cycle fan? or is it strictly there to just act as a resistor and drop voltage to 10v?
if just there as a resistor then im thinking about bypassing it and running a straight wire to give fans battery voltage at all times.
 

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I'd rather do it myself
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Discussion Starter #19
Yes it's only purpose is to slow down the fan. You can easily have hi speed when the ECU wants lo speed by splicing the hi and lo speed fan relay grounds together.
 
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