Electric fan switch

[Stinky]

I am thinking about putting an electric cooling fan on my 720.  I just did a search here and really didn't find anything about electric fan heat/thermo switches. 

 

I was looking at Jegs and Summit and half of the reviews for the ones that I was looking at are negative.

 

I'd like an adjustable sensor.

 

I've read bad things about using a probe in the radiator's fins (inconsistent readings).

 

They make em w/a relay, and also w/the sensor being a switch.

 

What would you use?

[datzenmike]

 

 

I have an in line fitting and just cut about 1" out of the lower rad hose and hose clamped it in place. I wasn't sure the sensor switch could handle the huge current when the fans come on so I used it to switch a relay and put a 40 amp fuse on it. I think it came out of a later Sentra 200sx. The gauge runs a hair above 1/2 on the marked 'run range' when driving and does not waiver unless idling or perhaps in stop and go traffic. The gauge will rise to about 2/3 or maybe 2 needle widths before the fans come on. I believe the sensor is set for around 190 and this works well and the gauge never rises once the fans come on. When idling long enough the fans come on for 10 seconds and off for about 30. This set up has it's own fuse and it's powered all the time. This means that after shut off if it heat soaks above 190 the fans come on without the ignition being on. Adjust-ability? what ever for? Just get something 10 degrees higher than your thermostat so it isn't coming on and off all the time. Mount in the lower hose where the coolant is the coolest so it doesn't come on from random heat spikes. 

[thisismatt]

I would want one that uses a controller or switch that runs through a range, not on/off at one specific temperature.  It's better for all the equipment if it's not constantly turning off/on.  Cooling fans draw a lot of current - it seems like a terrible idea *not* to use a relay triggered by the thermistor/thermal switch.

[nicklp]

Ok, this is stuff I've used in the past. The housing comes from the old SAAB cars which still come up in junkyards sometimes. Kind of large hose diameter. The irrigation fitting has to be ordered on line as Ace doesn't seem to carry it any more. I removed the anodizing, cut a hole, and welded on a nut. You can do this with any suitable tube. The napa temp switch is on at 85 C, off at 80 C (186.5 to 176 F). The one for the SAAB fitting can be found on ebay or from World Pac, which sells to the public through Carquest. The part number is 823 959 481 PLUS A LETTER for the temp range. The letter "E" is for 60-65C or 149-140F, no letter is 75-70C or 167-158F, Letter "D" is 82-77C or 179.6- 170.6F, letter "F" is for 92-87C or 197-188.6F. If you buy on ebay make sure of the temp range because people drop the letter sometimes in the listing. This one is threaded 22 millimeter, you can buy an axle nut at ace that works. I like to put these in the lower hose, bear in mind that the lower hose is where the cooled down coolant is going back in to the engine, so choose a lower temp than if you were putting the switch in the upper hose. Use a relay. My first post with pictures.

[Duncan]

I bought a relatively cheap Derale fan switch.  It has a radiator probe, adjustable temps for on/off, and an override function on it.  It works fine, except on a hot day I think it lets the car get a bit too warm before it turns the fan on.  I do have a stock 510 radiator with an L20 in my wagon, so it tends to run a bit warm on a hot day anyway.

 

 I just leave the fan switch on during the warmer months, and it keeps the temp steady instead of fluctuating up and down.  It was around $60.00 and it's been in use for about two years now with no problems..  It's not the ideal controller, but it works fine for my application.

 

 

Edited April 29, 2020 by Duncan

[datzenmike]

On 4/26/2020 at 3:14 PM, nicklp said:

Ok, this is stuff I've used in the past. The housing comes from the old SAAB cars which still come up in junkyards sometimes. Kind of large hose diameter. The irrigation fitting has to be ordered on line as Ace doesn't seem to carry it any more. I removed the anodizing, cut a hole, and welded on a nut. You can do this with any suitable tube. The napa temp switch is on at 85 C, off at 80 C (186.5 to 176 F). The one for the SAAB fitting can be found on ebay or from World Pac, which sells to the public through Carquest. The part number is 823 959 481 PLUS A LETTER for the temp range. The letter "E" is for 60-65C or 149-140F, no letter is 75-70C or 167-158F, Letter "D" is 82-77C or 179.6- 170.6F, letter "F" is for 92-87C or 197-188.6F. If you buy on ebay make sure of the temp range because people drop the letter sometimes in the listing. This one is threaded 22 millimeter, you can buy an axle nut at ace that works. I like to put these in the lower hose, bear in mind that the lower hose is where the cooled down coolant is going back in to the engine, so choose a lower temp than if you were putting the switch in the upper hose. Use a relay. My first post with pictures.

 

You want something close to 190 for the fan to come on, maybe 185. If it's below or at the thermostat rating it will be on all the time just like the mechanical fan it's supposed to be replacing. It should have a relay with a suitable fuse and wire directly to the battery. I don't know how much current those senders can switch off and on so a relay is can take the hit. I have those nice ones from the 720 or just about any '80 Nissan and I carry a spare. Don't use those glass Datsun fuses. I got those large GM bladed ones and carry several in the glove box. I have a thick wire and a 50 amp? fuse in a  holder. Directly wired, the fan is free to come on during a heat soak condition.

[nicklp]

I should have said what I used that in. The 86-76 C (on at 187 F, off at 169 F) one shown in the Saab housing with hoses still attached came out of my PLG-222 with an E-1 engine before I blew it up and started the A15 install. I've done this for a few different non-Datsun vehicles. A one-step-lower temp one works great in my old 4-cyl. Alfa, which has an aluminum block and head engine based on a 50's design and has a normal run temp of 180 F. And I live in sometimes hot AF Sacramento CA area. Wired same as yours, same experience with performance (rock solid temp control and comes on for a minute with heat soak). Volvo used a good 12-inch Bosch pusher fan on their AC condensers, easy to find at Pick-n-pull. The fan on the 222 is rumored to be from a Peugeot and came off a junk pile at the shop where I used the work.