HOW TO: Control an electric fan with a factory thermoswitch
can i use a 30amp relay without the 87a prong? one that just has 4? also does anyone have a picture of a s5 TII thermoswitch?? its the single wire one on the back of the waterpump housing isnt it??
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From: Atlanta
Arghx - Thank you for the great write up ... I have been thinking about doing this upgrade for some time now to get rid of the propeller up front ... However I didn't want to wire it switched or from ignition - So you have solved those problems.
My only question is ... These are the relays under the hood? Are they numbered? I guess my quesion is - How do I identify the relays I am looking for.
My only question is ... These are the relays under the hood? Are they numbered? I guess my quesion is - How do I identify the relays I am looking for.
1) use a spare OEM 4 pin relay (kind of like the ones under the hood near the front of the car) with an s5 style thermoswitch
2) use two heavy duty 5 pin aftermarket relays and an s4 thermoswitch
3) use an aftermarket 4 or 5 pin relay with an s5 style thermoswitch
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From: Syracuse New York
Arghx thanks for a great write up. I have a S4 thermo switch the wire that's hooked up to it now in the wiring harness does it go to the 1E on the ecu or do I need to run another wire to the ecu 1E . If it is the ecu 1E. Can I just cut it and run it to 87A on the relay and the fans ground. And the thermo switch go's to 86 on the relay. Is this correct, the rest I can follow on your diagram for the S4. Thanks
Arghx thanks for a great write up. I have a S4 thermo switch the wire that's hooked up to it now in the wiring harness does it go to the 1E on the ecu or do I need to run another wire to the ecu 1E . If it is the ecu 1E. Can I just cut it and run it to 87A on the relay and the fans ground. And the thermo switch go's to 86 on the relay. Is this correct, the rest I can follow on your diagram for the S4. Thanks
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From: Syracuse New York
For those of you doing an electric fan conversoin, you have multiple options for controlling the fan.
1. You can wire it to ignition power, but then the car will take a long time to warm up (if ever) and you will be draining the battery excessively.
2. You can wire it to a manual switch, but there's always the risk that you or anyone else driving the car may forget to turn it on.
3. You can use those crappy push-in radiator probe things, which hardly ever work.
4. You can use a Spal PWM fan controller, which will "throttle" the fan once configured correctly
5. You can use a thermoswitch, either a Mazda OEM one or a sensor off another car.
So there are multiple options for this. The automatic non turbo s4 cars came with a 195F/90C thermoswitch. The turbo cars came with a 207F/97C thermoswitch, the same temperature that the Rx-8's trigger their electric fans. Here is an OEM s4 turbo thermoswitch, located in the thermostat housing:
That is 3/8 NPT thread I believe. Here is the wiring diagram:
There are two relays. One controls fan power and one controls fan ground. With the key off, the fan will have ground but it will not have power. With the key on, the fan will have power but it will not have ground until the thermoswitch trigger temperature is reached. When the trigger temperature is reached, the thermoswitch will "remove" the signal to pin 86 of the ground relay. The chassis ground will be supplied to the fan through pin 87a, the normally closed pin. The fan will stay on until temps drop down below 195F/90C if you have a turbo thermoswitch. If you have an s4 nonturbo A/T thermoswitch, the ON and OFF temps will be lower.
It may look complicated, but that's about as simple as you're going to get using easily available relays. I tried to use splices and shared wires. The idle up function is achieved by sending a ground to s4 ECU pin 1E (same on turbo and non turbo) which will make the ECU think that the A/C is on. That will increase BAC valve duty cycle (more idle air) and advance the ignition timing from -5L -20T to 10L 10T, per the training manual.
1. You can wire it to ignition power, but then the car will take a long time to warm up (if ever) and you will be draining the battery excessively.
2. You can wire it to a manual switch, but there's always the risk that you or anyone else driving the car may forget to turn it on.
3. You can use those crappy push-in radiator probe things, which hardly ever work.
4. You can use a Spal PWM fan controller, which will "throttle" the fan once configured correctly
5. You can use a thermoswitch, either a Mazda OEM one or a sensor off another car.
So there are multiple options for this. The automatic non turbo s4 cars came with a 195F/90C thermoswitch. The turbo cars came with a 207F/97C thermoswitch, the same temperature that the Rx-8's trigger their electric fans. Here is an OEM s4 turbo thermoswitch, located in the thermostat housing:
That is 3/8 NPT thread I believe. Here is the wiring diagram:
There are two relays. One controls fan power and one controls fan ground. With the key off, the fan will have ground but it will not have power. With the key on, the fan will have power but it will not have ground until the thermoswitch trigger temperature is reached. When the trigger temperature is reached, the thermoswitch will "remove" the signal to pin 86 of the ground relay. The chassis ground will be supplied to the fan through pin 87a, the normally closed pin. The fan will stay on until temps drop down below 195F/90C if you have a turbo thermoswitch. If you have an s4 nonturbo A/T thermoswitch, the ON and OFF temps will be lower.
It may look complicated, but that's about as simple as you're going to get using easily available relays. I tried to use splices and shared wires. The idle up function is achieved by sending a ground to s4 ECU pin 1E (same on turbo and non turbo) which will make the ECU think that the A/C is on. That will increase BAC valve duty cycle (more idle air) and advance the ignition timing from -5L -20T to 10L 10T, per the training manual.
Arghx This is how i'm going to do it. I just want to know if the wire that hooked up to it now go's to the 1E pin so I don't have to run a new wire to the 1E. And I think you said the S4 non turbo will work in a S4 turbo, It's just kicks on at a lower temp. Thanks
The whole pin 1E thing tricks the ECU into thinking the A/C has been activated, because unlike the FD there is no idle-up system for a full sized electric fan. You should run a separate wire down to the ECU. Follow the diagram.
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From: Syracuse New York
"the wire hooked up to it now" -- are you referring to the factory thermoswitch wire on a car that came with the thermoswitch from the factory? that wire goes to the factory fan control module for the small auxiliary fan on automatic and turbo models.
The whole pin 1E thing tricks the ECU into thinking the A/C has been activated, because unlike the FD there is no idle-up system for a full sized electric fan. You should run a separate wire down to the ECU. Follow the diagram.
The whole pin 1E thing tricks the ECU into thinking the A/C has been activated, because unlike the FD there is no idle-up system for a full sized electric fan. You should run a separate wire down to the ECU. Follow the diagram.
I'm curious what thermoswitches people have used other than S4 and S5? I decided to go with something other than OEM so I can get a little lower switch. I'm wanting 195 F.
I went to my local NAPA to look one up in their books...only to find that they no longer keep those books. They are now QAD/CO and was told all their parts have been realigned.
With that said, anyone have any they have used?
Also I'd love to wire in an FD fan control module. What I've found so far is this. But how do I wire it in with a S5 relay system?
I went to my local NAPA to look one up in their books...only to find that they no longer keep those books. They are now QAD/CO and was told all their parts have been realigned.
With that said, anyone have any they have used?
Also I'd love to wire in an FD fan control module. What I've found so far is this. But how do I wire it in with a S5 relay system?
I've never personally run the Starion fan switch but they have them on RockAuto Parts for cheap.
That was me who originally posted that image ^ I have never seen an actual wiring diagram (with wire colors and pinout) of the cooling fan control module. This is because the module was in 95 models and in earlier models that had a recall performed. The wiring diagrams floating around don't reflect that.
That was me who originally posted that image ^ I have never seen an actual wiring diagram (with wire colors and pinout) of the cooling fan control module. This is because the module was in 95 models and in earlier models that had a recall performed. The wiring diagrams floating around don't reflect that.
Joined: May 2006
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From: Jacksonville, Tampa & Tallahassee
I used a subaru switch, comes on@ 194 off @ 185. Got the last two (by that manufacturer) in the country from napa a few months back. I'm sure they still stock the switch, just not sure on the new part number.
Joined: Apr 2005
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From: And the horse he rode in on...
Here it is as a kit with relay and harness.
http://m.summitracing.com/parts/SUM-890016
Summit also has a 185*/170* version Most switches have a 15* swing to prevent short cycling.N thus if you turn it on at 195* it may never turn off.
Here is what I use in my Vert-on 200* off at 185*. http://m.summitracing.com/parts/SUM-890018
Here it is as a kit with relay and harness.
http://m.summitracing.com/parts/SUM-890016
Summit also has a 185*/170* version Most switches have a 15* swing to prevent short cycling.N thus if you turn it on at 195* it may never turn off.
Here it is as a kit with relay and harness.
http://m.summitracing.com/parts/SUM-890016
Summit also has a 185*/170* version Most switches have a 15* swing to prevent short cycling.N thus if you turn it on at 195* it may never turn off.
About the never turning off thing. I swapped PMs with someone who is using an Audi thermoswitch. He said his never turns off.
Joined: Apr 2005
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From: And the horse he rode in on...
Thanks, the Summit one is half the price of the S5 OEM one. I have a 40A relay collecting dust, I believe it was used for a previous vert's antenna.
About the never turning off thing. I swapped PMs with someone who is using an Audi thermoswitch. He said his never turns off.
About the never turning off thing. I swapped PMs with someone who is using an Audi thermoswitch. He said his never turns off.
about 50*otherwise it runs. That's why I use low speed on my Viliager fan.
I suspect that it would cycle if the sender were in the oem spot in the water pump.
I was going to get an aluminum thermoneck from mazdatrix and have that tapped. Now I'm considering having a small plate welded to the bottom of koyo rad and then have that plate tapped. I'm wondering what is the better location for the sensor.
Summit Racing thermoswitch arrived yesterday, it's much larger/deeper than expected. I think my only options are to either tap the bottom of my koyorad or use a hose adapter on my upper rad hose.
How much of a temp drop should I expect to see at the bottom of my radiator?
How much of a temp drop should I expect to see at the bottom of my radiator?
Works like a charm! Just installed the relays today.... started it up (different story) and waited... I was so worried it was going to overheat.... then all the sudden the idle drops, I hear a loud whirring sound and I smile! Thanks arghx!
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From: wyoming
relays are not my thing. and all this just makes me wanna keep my clutch fan.
but it does look better with an efan.
And on the subject can i use a thermoswitch from the vehicle i take the fan out of?
but it does look better with an efan.
And on the subject can i use a thermoswitch from the vehicle i take the fan out of?
I swapped PMs with someone about this type thing. From those PMs I have an idea. What about using the spot for S5 thermoswitch on the back of the waterpump housing. The lower one. I believe it controls a/c efan (if your car has one) and also adjusts idle for when the a/c kicks on. It switches at 207 deg. What about either using that switch for both it's OEM purpose and also to turn on the rad fan? Use a relay to switch polarity, just like with the power antenna when using aftermarket headunit.
The other idea is using my Summit switch in the OEM thermoswitch location to do both OEM and rad efan. I'm very much learning electronics, so bare with me. But can't a relay be used to reverse polarity from the Summit signal to ground? Split the signal so one goes to rad efan unchanged. The other switch polarity to ground and wire that into engine harness.
Would that have the effect of bumping idle up every time the efan or a/c kicked on?
The other idea is using my Summit switch in the OEM thermoswitch location to do both OEM and rad efan. I'm very much learning electronics, so bare with me. But can't a relay be used to reverse polarity from the Summit signal to ground? Split the signal so one goes to rad efan unchanged. The other switch polarity to ground and wire that into engine harness.
Would that have the effect of bumping idle up every time the efan or a/c kicked on?
I swapped PMs with someone about this type thing. From those PMs I have an idea. What about using the spot for S5 thermoswitch on the back of the waterpump housing. The lower one. I believe it controls a/c efan (if your car has one) and also adjusts idle for when the a/c kicks on. It switches at 207 deg. What about either using that switch for both it's OEM purpose and also to turn on the rad fan? Use a relay to switch polarity, just like with the power antenna when using aftermarket headunit.
The other idea is using my Summit switch in the OEM thermoswitch location to do both OEM and rad efan. I'm very much learning electronics, so bare with me. But can't a relay be used to reverse polarity from the Summit signal to ground? Split the signal so one goes to rad efan unchanged. The other switch polarity to ground and wire that into engine harness.
Would that have the effect of bumping idle up every time the efan or a/c kicked on?
I don't have the a/c efan, but I do have a S5 with A/C and that OEM switch. I believe for my purposes that switche's only purpose is to idle up when A/C comes on.
Drawing up a diagram is where my problems will start. I understand enough to get the larger concepts, but I don't know enough to draw up diagrams. I'll spend some time researching the power antenna relay and reversing polarity. It can't be that difficult.......right???
