ABC's of 80's Cooling Part III - Press Switch

[blarsen]

Sumotoy
I know that some people on here like to give you crap..... I am sorry about that! I installed the pusher fan and LOVE it, its makes the AC cooler and the motor run cooler also..
thanks for all the time you have invested in trying to help the rest of us..
keep up the good work..
later
Bret

 

[clarkrw3]

Mine has been working like a charm....and now that my 80 is my daily driver in the hottest months of Phx we will have a true test.

 

[McDowra]

bump for a great mod, thanks Sumotoy

 

[citadel]

bump again for an awesome mod.... just rewired my fan based on Sumotoy's guidance.... In 106 degree ambient Texas heat the after run lasts about 15- 30 seconds max....

 

[sandcruiser]

everyone still loving this mod? I'm thinking to do it next week.

 

[S.CarolinaFZJ80]

I just finished it up last night. I did the retro-stock install using the CDS relay & fuse ports in the stock fuse box. Kind of a PITA to route all of the wires but a good clean install. I used a 2nd generation 4Runner fan from the junkyard. There are several more fans available if anyone wants one. I can also include the wiring for the pressure switch for those interested.

 

[clarkrw3]

everyone still loving this mod? I'm thinking to do it next week.

YES...very glad I did it

 

[BrotherRob]

Mine worked good for 3 years. Then the fan died, so I upgraded the fan clutch. Works much better now.

 

[sandcruiser]

cool. I've already got the stock aux fan, and the relay hooked up to the compressor clutch, but I have never liked that the fan cuts out when A) the compressor turns off due to being cold enough or B) in the event of an overheat situation.

So I'm just looking at wiring the relay differently such that it will turn on/off w/ the 2ndary pressure circuit.

I like the idea of having the after-run option as well. Seems like a good thing to have.

 

[SUMOTOY]

cool. I've already got the stock aux fan, and the relay hooked up to the compressor clutch, but I have never liked that the fan cuts out when A) the compressor turns off due to being cold enough or B) in the event of an overheat situation.
So I'm just looking at wiring the relay differently such that it will turn on/off w/ the 2ndary pressure circuit.
I like the idea of having the after-run option as well. Seems like a good thing to have.

That should be easy, see post 51. In your case, you just have to change a couple wires to the relay.

First time I've seen this post in a while. Thanks to those that have expressed their appreciation for posting the mod. I've run mine without issue since my post 1. I found the after-run allows a faster at-vent cooling time on hot restarts.

Cheers

Scott J
94 FZJ80 Supercharged

 

[sandcruiser]

my motivation to start the job is that the relay is in a bad place now (stuffed down in the battery box, dangling)-- so I want to move it completely. I also want a manual override/manual on.

So my plan is to wire the fan from fused + and run the ground wire through to relay (30) then from relay (87) to a convenient ground.

Then I'll run fused + to the relay (85) and from relay (86) to an On/Off/On switch in the dash. The top contact on the switch will go to the AC pressure switch and be labeled "auto". The bottom contact will go directly to ground and be labeled "On", the Middle position will therefore be "Off" for water crossings or to kill the after-run if wanted/needed.

I may put the relay in the + wire to the fan. Need to look at how the fan grounds itself. It doesn't make much difference to me- whichever is easiest.

ordered the terminals from CDan.... so I may go ahead and wire everything to test while I wait.

 

[SUMOTOY]

my motivation to start the job is that the relay is in a bad place now (stuffed down in the battery box, dangling)-- so I want to move it completely. I also want a manual override/manual on.

So my plan is to wire the fan from fused + and run the ground wire through to relay (30) then from relay (87) to a convenient ground.

Then I'll run fused + to the relay (85) and from relay (86) to an On/Off/On switch in the dash. The top contact on the switch will go to the AC pressure switch and be labeled "auto". The bottom contact will go directly to ground and be labeled "On", the Middle position will therefore be "Off" for water crossings or to kill the after-run if wanted/needed.

I may put the relay in the + wire to the fan. Need to look at how the fan grounds itself. It doesn't make much difference to me- whichever is easiest.

ordered the terminals from CDan.... so I may go ahead and wire everything to test while I wait.

<edit> Got confused as to your project, since you are using the relay to ground the fan wiring - not feed it power. Most hi amp relays switch the + side of the device, not the negative side. Especially in a motor, since brush wear or burned motor can short to the chassis of the motor. I do not recommend a 12v hi amp relay on the ground circuit of this fan mod.

HTH

Scott J
94 FZJ80 Supercharged

 

[sandcruiser]

nice point.
Ok. +12v to relay to fan to ground.
Makes it easy to add a jumper from 30 to 85 to power the relay.

 

[sandcruiser]

I'm planning to wire this up using the rear heater switch (which already has the little fan icon and everything).

It is a 3 position switch and I want it to function as follows
left alone (middle)= auto... turns on/off w/ the AC pressure switch
left (lo)= fan forced on, to cool the truck w/ AC off
right (hi)=fan off (for water xing or parked in hot sun on hot day)


any electrical gurus out there have observations on how to make it work?
I don't want the LEDs running when the truck isn't running. But I do want them running when the truck is running. And I want the fan to be able to after-run when hot.

Help!?!?

Those LEDs are making the circuit a little too complicated for my brain to grasp.

 

[sandcruiser]

ok, I think I've got it.... anyone care to review and comment before I start wiring?

first: I'm using the stock Rear Heater Switch (RHSW) that was already in my truck. I pulled the rear heater a while back, but the wiring and switch are intact.

here's the RHSW diagram

It seems to use the yellow wire for +12v
then connects (blue/black) to "Hi"
and (blue/yellow) to "Lo"
(black/white)= ground
Those are meant to be ground circuits from the heater fan

My impression is that if I wire it up as follows, it'll work for me

+12v from IGN source to the switch will illuminate the LEDs only when IGN on. So I'll just leave that alone.
Black/white=Ground. I'll leave that alone.
Background lighting--- also left alone, as is.
That just leaves me with the two wires that come from the RH fan relay.

I plan to wire up my Aux fan relay such that it gets power from a fused +12v @ battery
I'll jump 30 to 85 to provide +12v for the relay coil.
87 will go to the Aux fan to power it, then fan will be grounded.

86 (coil on Aux fan relay), will be 2 wires.
The first will go to the pressure switch on the AC circuit, then the (blue/yellow), to rear heater switch.
The second will go to the (blue/black) and directly to the rear heater switch.

When in "Lo", the orange LED will light up and the fan will be on "auto" mode.
When in "Hi" the green LED will light up, and the fan will be 'forced' to be "on".
When the switch is centered, the fan will be off.

When IGN is off, the fan can still run if in "Lo" but the LED won't come on.

To me, this sounds right. But I'm only on my first cup of coffee and distracted by a pretty bird in the tree outside my window... so if you see an issue, please let me know.

 

[SUMOTOY]

ok, I think I've got it....
To me, this sounds right. But I'm only on my first cup of coffee and distracted by a pretty bird in the tree outside my window... so if you see an issue, please let me know.

Looks ok to me after coffee. You do need to run the other side of the pressure switch to ground.

HTH

Scott J
94 FZJ80 Supercharged

 

[sandcruiser]

Scott
thanks for the comment.
Are you sure re: ground?

I'm planning to put 2 wires coming from 86 on the relay. I wire will pass through the px sw to the Rear Heater switch, to ground
the other wire will go to the rear heater sw to ground

I think that will mean that the px switch will close when the pressure is 'correct' and if I also close the rear heater switch, I'll have a clear path to ground.

or, if the heater switch is closed to "hi" then I'll also have a ground path.

I assume that the px switch opens/closes regardless of what is connected, based on the pressure in the AC line. Is that a bad assumption?

 

[SUMOTOY]

Scott
thanks for the comment.
Are you sure re: ground?

I'm planning to put 2 wires coming from 86 on the relay. I wire will pass through the px sw to the Rear Heater switch, to ground
the other wire will go to the rear heater sw to ground

I think that will mean that the px switch will close when the pressure is 'correct' and if I also close the rear heater switch, I'll have a clear path to ground.

or, if the heater switch is closed to "hi" then I'll also have a ground path.

I assume that the px switch opens/closes regardless of what is connected, based on the pressure in the AC line. Is that a bad assumption?

One switch position goes to ground direct, the other position goes to ground via the pressure switch. The pressure switch is 2 pins. One pin will come from your switch "pos 1" the other pin will go to ground. Switch Pos 1 then will use the ground as dictated by the Pressure switch, Switch Pos 2 then will use ground directly (over ride). Pos 0 is no ground/sw ground to relay pin 86

Let me know if I need to fire another pot of coffee

Scott J
94 FZJ80 Supercharged

 

[sandcruiser]

ok, I gave it a try...

putting 12v to pole 85. then running 86 to the blue/black wire does close the relay when the heater switch is pushed to HI.

blue/yellow wire activates the relay when LO.

I was wrong on LED color, by the way-- LO is green, HI is amber. fwiw.

Next step is trying it out w/ the px switch.

Looks like I can use the EFI relay in the stock fuse box. and the fuse for same. it is +12v all the time... just need to figure out which wires to use to activate it. (diesel, thus no need for EFI, but the relay is still there 'cuz it used to be a gasser)

anyone know Max current for the efi relay?

 

[SUMOTOY]

ok, I gave it a try...

putting 12v to pole 85. then running 86 to the blue/black wire does close the relay when the heater switch is pushed to HI.

blue/yellow wire activates the relay when LO.

I was wrong on LED color, by the way-- LO is green, HI is amber. fwiw.

Next step is trying it out w/ the px switch.

Looks like I can use the EFI relay in the stock fuse box. and the fuse for same. it is +12v all the time... just need to figure out which wires to use to activate it. (diesel, thus no need for EFI, but the relay is still there 'cuz it used to be a gasser)

anyone know Max current for the efi relay?

The pressure switch circuit then should be relay (grnd) to pressure switch pin 1, Press switch pin 1 to switch pos 1. Now, when you hit the switch with the pressure switch attached, the pressure switch has a complete circuit to ground.

HTH

Scott J
94 FZJ80 Supercharged