BluePrint Engines

Visit our community sponsor

Thanks Thanks:  0
Likes Likes:  0
Results 1 to 15 of 15

Thread: Cooling fans, thermostats, switches, wiring

  1. #1
    Senior Member
    Join Date
    May 2014
    Location
    Burlington, WI
    Posts
    689
    Post Thanks / Like
    Blog Entries
    1

    Cooling fans, thermostats, switches, wiring

    I followed the instructions provided with the RF wire harness and think I did a pretty good job. Adding the Breeze Adjustable Thermostat Cooling Fan Switch and splicing in a toggle switch to turn the cooling fan on manually, may have complicated things. And, for me, following the schematic had been a challenge. For example, I am not quite clear on the relationship of the dk green-fan thermo switch wire, the dk blue -cooling fan wire, the thermo switch mounted in the intake manifold water port, the Breeze adjustable switch and the flow of these wires in and out of the fuse panel and the relay within the panel. I guess I'm asking what triggers what and what's the flow? And, how does the water temp guage tie into the system?

  2. #2
    Senior Member CraigS's Avatar
    Join Date
    Feb 2011
    Location
    Blacksburg, Va
    Posts
    4,707
    Post Thanks / Like
    Your last question is all I can help with. The temp gauge and it's sender have no connection to the fan system. The temp sender is a variable sender over a wide range of temps. The fan sender is an on/off switch. It usually has an on temp and an off temp that are about 10 degrees apart.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  3. #3
    Senior Member edwardb's Avatar
    Join Date
    Feb 2011
    Location
    Lake Orion, Michigan
    Posts
    10,544
    Post Thanks / Like
    This is slightly confusing because the RF harness changed 1-2 years ago. So some information you will see on this subject may not be correct based on what version the builder was using. In the prior version (was on my #7750 build) the cooling fan circuit was an IGN FEED circuit and had a wire in the front harness as well as in the dash harness. Won't dwell on that one because I'm guessing that's not what you have. The newer version (is on my #8674 Anniversary build) the cooling fan circuit is a BATT FEED circuit and only has a single control wire in the front harness. Operation is really very simple. The DK BLU-COOLING FAN wire in the front harness goes to the +12V terminal on the cooling fan itself. The other terminal on the cooling fan goes to ground. The DK GRN-FAN THERMO SWITCH wire goes to your cooling sensor switch. When the sensor wire is grounded (e.g. sensor closes) the cooling fan relay in the RF panel closes, +12V goes to the cooling fan, and it runs.

    You can test this function pretty easily. With nothing hooked up except +12V to the RF panel, touch the GRN-FAN THERMO SWITCH wire to ground. You should hear the cooling fan relay click. If you put a VOM on the DK BLU-COOLING FAN wire, you should see +12V switching on. As already stated, this is a battery circuit, so the fan circuit will run with or without the ignition key being on. Something to keep in mind. Some like this setup. Some don't.

    I personally haven't used the Breeze Adjustable Thermostatic Cooling Fan Switch. But looking at the listing on the website, it has its own sensor in the radiator tubes and fins, right? So that would be the only cooling fan sensor you would use. I wouldn't think you would have both a sensor in the intake manifold water part and the Breeze switch. Looking at the schematic for the Flex-a-lite adjustable temperature control Mark uses, it's intended to also actually switch the fan on and off, plus shows an override switch. In the simplest terms, you could wire that switch to complete the ground circuit for the GRN-FAN THERMO SWITCH. But I'm not sure if it needs +12V to operate. If so, you may need to ditch the RF cooling fan function and just provide +12V to the Flex-a-lite controller and wire as their schematic shows. Personally I've used the intake manifold water part for a sensor and the RF wiring on both SBF builds and it works fine. The adjustable aspect of the Breeze part is interesting, but you can get manifold sensors in different heat ranges and the job gets done.

    As for a manual override switch with the RF harness, you just need to piggy back onto the GRN-FAN THERMO SWITCH and provide another path to ground on the instrument panel.

    Yes it's all a bit confusing. Two different RF harness versions and an aftermarket controller that maybe isn't 100% compatible with either. But hope that helps.
    Last edited by edwardb; 01-17-2017 at 09:00 AM.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

  4. #4
    Senior Member
    Join Date
    May 2014
    Location
    Burlington, WI
    Posts
    689
    Post Thanks / Like
    Blog Entries
    1
    The Breeze Adjustable Thermostatic Fan Switch kit does have its own sensor probe that you insert into the cooling fins and a fan switch allowing you to raise or lower the set point. After I absorb what you've laid out here, which makes sense, I will reach out to Mark to see whether he agrees that maybe my current set up is redundant, and possibly not necessary. Either way, I am now committed to using his kit, so I'll make it work.

    Considering I always planned to have under-dash override fan anyway, and now understand how simple the current RF system is (read "rookie"), I may have passed on the kit. Next build. At times I seem to make some things more complicated than they need to be. ? Read "rookie" again.

  5. #5
    Senior Member
    Join Date
    May 2014
    Location
    Burlington, WI
    Posts
    689
    Post Thanks / Like
    Blog Entries
    1
    I reached out to Mark and he was very helpful. Along with your (Paul & CraigS) advise I was able to track down the culprit. After re reading the RF wiring harness instruction manual I found that the harness provides 2 locations to run the electric fan using a thermostat switch. I apparently didn't read this clearly when I first ran the front engine harness wires. I missed what a 3rd green wire in the front harness was for and subsequently used it for something člse. I was essentially grounding the thermostat switch wire.

    Tip: if you're not certain what a wire is for or how to connect it...don't ignore it.

  6. #6
    Senior Member lahrs37's Avatar
    Join Date
    Jul 2014
    Location
    Philadelphia
    Posts
    377
    Post Thanks / Like
    I am literally in the middle of installing the breeze adjustable thermostatic fan switch. edwardb - if I am understanding you correctly, the green wire can basically be capped off because it is not needed for this application, right? That was my initial thought. The fan gets its power from the fused 12v blue wire. It is activated by the the switch which is in turn triggered by the temperature reading from the probe in the radiator. That is it. It is pretty much a closed system. There will be a completely different circuit for the temperature gauge - but that has nothing to do with the operation of the fan.
    5.0 HO from a '93 Mustang, SVE heads, Trickflow stage 1 cam, Trickflow Street Burner intake manifold, T-5 w/mid shift, IRS
    Delivery 9-10-16, First Start 12-28-16, First Go-Kart 2-18-17
    Build thread: http://thefactoryfiveforum.com/showt...MK4-8951-Build

  7. #7
    Senior Member edwardb's Avatar
    Join Date
    Feb 2011
    Location
    Lake Orion, Michigan
    Posts
    10,544
    Post Thanks / Like
    That of course explains why you were hearing the cooling fan relay clicking every time you connected the battery, discussed in a different thread. Electricity is funny that way. Glad you were able to get it worked out.
    Last edited by edwardb; 01-18-2017 at 08:39 AM.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

  8. #8
    Senior Member edwardb's Avatar
    Join Date
    Feb 2011
    Location
    Lake Orion, Michigan
    Posts
    10,544
    Post Thanks / Like
    Quote Originally Posted by lahrs37 View Post
    I am literally in the middle of installing the breeze adjustable thermostatic fan switch. edwardb - if I am understanding you correctly, the green wire can basically be capped off because it is not needed for this application, right? That was my initial thought. The fan gets its power from the fused 12v blue wire. It is activated by the the switch which is in turn triggered by the temperature reading from the probe in the radiator. That is it. It is pretty much a closed system. There will be a completely different circuit for the temperature gauge - but that has nothing to do with the operation of the fan.
    In simple terms (e.g. how the RF harness was designed to work) you can't cap the green wire. Grounding that wire is what closes the cooling fan relay which in turn provides the +12V to the blue wire. Maybe ThickCobra can explain how Mark said to hook up his adjustable thermostatic fan switch. I haven't installed one so have no personal experience. Somehow that switch opening and closing has to get into the RF harness.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

  9. #9
    Senior Member
    Join Date
    May 2014
    Location
    Burlington, WI
    Posts
    689
    Post Thanks / Like
    Blog Entries
    1
    Quote Originally Posted by lahrs37 View Post
    I am literally in the middle of installing the breeze adjustable thermostatic fan switch. edwardb - if I am understanding you correctly, the green wire can basically be capped off because it is not needed for this application, right? That was my initial thought. The fan gets its power from the fused 12v blue wire. It is activated by the the switch which is in turn triggered by the temperature reading from the probe in the radiator. That is it. It is pretty much a closed system. There will be a completely different circuit for the temperature gauge - but that has nothing to do with the operation of the fan.
    As Mark explained to me, his kit takes all of the RF cooling fan wiring out of the picture. As his diagram shows, you need a 12v power supply either directly from the fuse box per his diagram or use another power source, he suggested the heater wire, if your not installing a heater. Alternatively, use the RF cooling fan wiring, dk blue, and incorporate the dk green thermostat switch wiring. As you know, without using the dk green thermostat wire, you have no power to the dk blue cooling fan wiring.

    I haven't quite figured out how to do it, but I'll be working on it today. You are fortunate that you are just starting it. My wiring is all done, but doesn't work, so I'll be revisiting all my wiring on this area. You can reach out to Mark if you need more guidance. I hope this helps.

  10. #10
    Well Used Member boat737's Avatar
    Join Date
    Feb 2016
    Location
    So. Bay (So. Calif.)
    Posts
    872
    Post Thanks / Like
    I have the Breeze (flexalite) adjustable fan sensor, but wired it differently than his instructions. The instructions say to run the 12v fan power through the switch, but that adjustable sensor does not need +12v positive to work. It's just a heat sensitive mechanical (I assume anyway) switch. It's an ON-OFF, so I just used the green fan thermo switch wire that was on the front harness at the radiator to ground through that sensor. I also have the thermostat housing sensor wired to the green fan thermo switch wire that was in the engine harness hooked up as well. Both of those green wires are in the same circuit. Either wire when grounded will run the fan. Either switch will ground the circuit, just like if you run a toggle switch to ground. In theory you could have as many switches to ground as you wanted, and any one of them would run the fan, and it wouldn't matter if they were all grounded, or just one. Bottom line, I just used that sensor as a grounding switch and not a power switch.

    I suppose the biggest difference in using the switch to either ground or to run power, is that by grounding (and using the RF wiring and relay) the fan will run with ignition off (until it cools sufficiently). By using that sensor as a power switch, you can wire it to have the fan off with the ignition off (the fan will only run with ignition on.)
    Last edited by boat737; 01-18-2017 at 10:04 AM.
    If Brute Force doesn't work, you're not using enough of it.
    Basic Stuff: MK4 Complete Kit #8439, Wilwood's, 17" Halibrands. Extra Stuff: Stainless brake and fuel lines, Breeze cooling, Battery mount, SS Roll Bar. Old Fart Stuff: Heater, Seat Heaters, Footbox Fresh Air, Stereo, Keyless ignition, Power Steering, Hyd Clutch.
    Young & Dumb Stuff: 427w Dart, TKO600, 3 link Moser M9/Ford 9", 3.5:1, Eaton TruTrac Posi. Graduation Thread

  11. #11
    Senior Member lahrs37's Avatar
    Join Date
    Jul 2014
    Location
    Philadelphia
    Posts
    377
    Post Thanks / Like
    Quote Originally Posted by ThickCobra View Post
    Alternatively, use the RF cooling fan wiring, dk blue, and incorporate the dk green thermostat switch wiring. As you know, without using the dk green thermostat wire, you have no power to the dk blue cooling fan wiring.
    I thought that the blue wire was powered and the green was ground. Here is a picture from the instructions:

    My understanding is that the dk blue wire comes from the fuse box and connects to the fan switch. When the switch is activated by the probe it turns on the circuit. The power then flows from the fuse box, through the dk blue wire, through the fan switch, to the fan motor, and then finally to chasis ground. I don't see where the dk green wire would come into it.

    boat737 - I think I get what you are saying too. Though it's possible that I am enough of an electrical noob that I am messing this up big time.
    5.0 HO from a '93 Mustang, SVE heads, Trickflow stage 1 cam, Trickflow Street Burner intake manifold, T-5 w/mid shift, IRS
    Delivery 9-10-16, First Start 12-28-16, First Go-Kart 2-18-17
    Build thread: http://thefactoryfiveforum.com/showt...MK4-8951-Build

  12. #12
    Well Used Member boat737's Avatar
    Join Date
    Feb 2016
    Location
    So. Bay (So. Calif.)
    Posts
    872
    Post Thanks / Like
    Quote Originally Posted by lahrs37 View Post
    I thought that the blue wire was powered and the green was ground. Here is a picture from the instructions:

    My understanding is that the dk blue wire comes from the fuse box and connects to the fan switch. When the switch is activated by the probe it turns on the circuit. The power then flows from the fuse box, through the dk blue wire, through the fan switch, to the fan motor, and then finally to chasis ground. I don't see where the dk green wire would come into it.

    boat737 - I think I get what you are saying too. Though it's possible that I am enough of an electrical noob that I am messing this up big time.
    Just to be sure, you do have the newer RF harness? That has a front harness (or at least mine does) green switch-grounding wire, as well as the sending units & elec. choke harness green switch-grounding wire. Funny, I just checked my RF schematic, and it does not show the front harness green wire, only the sending units harness shows the green wire. But I had a green wire both those harnesses.

    Anyway, I just ran both those green wires through the sensor switches (one to the Breeze/flexalite radiator sensor, and the other to the thermostat housing sensor), so either one will ground and turn on the fan. I hooked the blue wire up directly to the fan motor, and grounded the other wire coming out of the fan motor.

    Tell you what, just put a test light between the blue wire and ground, and then take that green engine harness wire (and/or the front harness green wire, not the horn wire though, that's green too) and touch it to ground. That should light the test light, with the ignition on or off. Then we know for sure you have the later style RF harness.
    If Brute Force doesn't work, you're not using enough of it.
    Basic Stuff: MK4 Complete Kit #8439, Wilwood's, 17" Halibrands. Extra Stuff: Stainless brake and fuel lines, Breeze cooling, Battery mount, SS Roll Bar. Old Fart Stuff: Heater, Seat Heaters, Footbox Fresh Air, Stereo, Keyless ignition, Power Steering, Hyd Clutch.
    Young & Dumb Stuff: 427w Dart, TKO600, 3 link Moser M9/Ford 9", 3.5:1, Eaton TruTrac Posi. Graduation Thread

  13. #13
    Senior Member lahrs37's Avatar
    Join Date
    Jul 2014
    Location
    Philadelphia
    Posts
    377
    Post Thanks / Like
    Quote Originally Posted by boat737 View Post
    Tell you what, just put a test light between the blue wire and ground, and then take that green engine harness wire (and/or the front harness green wire, not the horn wire though, that's green too) and touch it to ground. That should light the test light, with the ignition on or off. Then we know for sure you have the later style RF harness.
    I will do just that tonight.
    5.0 HO from a '93 Mustang, SVE heads, Trickflow stage 1 cam, Trickflow Street Burner intake manifold, T-5 w/mid shift, IRS
    Delivery 9-10-16, First Start 12-28-16, First Go-Kart 2-18-17
    Build thread: http://thefactoryfiveforum.com/showt...MK4-8951-Build

  14. #14
    Senior Member edwardb's Avatar
    Join Date
    Feb 2011
    Location
    Lake Orion, Michigan
    Posts
    10,544
    Post Thanks / Like
    Quote Originally Posted by lahrs37 View Post
    I thought that the blue wire was powered and the green was ground. Here is a picture from the instructions:

    My understanding is that the dk blue wire comes from the fuse box and connects to the fan switch. When the switch is activated by the probe it turns on the circuit. The power then flows from the fuse box, through the dk blue wire, through the fan switch, to the fan motor, and then finally to chasis ground. I don't see where the dk green wire would come into it.
    boat737 - I think I get what you are saying too. Though it's possible that I am enough of an electrical noob that I am messing this up big time.
    Very important to understand which wiring harness you have, as I said in my first post. Probably by now most are the newer version. But some of the older posts on this subject, plus even some suggestions received now on the forum, may not recognize the difference. The light bulb test suggested is a good one to confirm what you have. If the newer version, the circuit won't work without one of the dark green wires being grounded to turn on the fan.

    Based on boat373's post confirming the Breeze adjustable switch is mechanical only and doesn't need power, connecting it up should be really simple. Dark blue wire to the fan. Dark green wire to the Breeze (Prestolite) fan switch. Other side of switch to ground. Switch closes, fan runs. Seems like it should be that easy.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

  15. #15
    Senior Member
    Join Date
    May 2014
    Location
    Burlington, WI
    Posts
    689
    Post Thanks / Like
    Blog Entries
    1
    Quote Originally Posted by lahrs37 View Post
    I will do just that tonight.
    Just curious, did you install the Breeze kit and are you set?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Brown County Customs

Visit our community sponsor