^^^ Yup^^^.... Use the relay as the heavy switcher commanded on by by a low amperage power supply..... Your 10 amp fuse! A regular test lamp connected in series to either a power or ground source is enough to trip the relay....
Relays are used to send full power to a particular device while allowing a switch for that device to run significantly smaller wiring. In this diagram, our switch is connected on the "hot" or positive side. The wire to the switch and from the switch to the relay can be much thinner than the power wires. *Note that you can connect the switch input and the power for the relay to the same point, after the proper size fuse, of course.
***Accessory being your supplemental rad cooling fan***
-- Edited by 67Poncho on Thursday 26th of July 2012 01:32:00 PM
installed a 20 amp automatic reset circuit breaker on rad support
searched out a connection on the fuse panel that is alive only when the key is on - marked ACC
connected all the wiring including an underdash switch so that I have control
Then when I fired up the system it blew the radio fuse and the power to the ACC connection. It appears that this ACC connection is powered up thru the 10amp radio fuse.
So my question is where else can I take a power lead off of that is only powered up when the ignition key is turned on?
I am aware that there are sensors available that mount in the rad fins that only turn the fan on when the rad reaches a specified temperature and thus could be connected to an always live terminal. But I wanted to have control.
Anyone familiar enough with the electrical systems that can suggest where to tap into?
Sounds like I'm going to have to consult someone a little more knowledgeable in electrics. I don't understand the concept of the relay. So don't know exactly what to ask for when buying a part.
I do have the fan hooked up as a "pusher".
When I fed the switch directly from an always hot terminal everything appeared to work. Still sounds like I'm missing something.
-- Edited by norontcan on Thursday 26th of July 2012 10:28:00 AM
Pin 30: Heavy 12-14 RED guage wire with proper rated fuse from the battery positive to handle the draw of the coolant fan motor. Pin 85: This will be your switched 12v source to activate the relay. You can put in a little 3amp fuse here at the power source to protect the switch and wiring to the relay. Pin 86: This pin will go directly to ground with a 16-18 gauge BLACK wire. This is required and completes the circuit for the coil in the relay for the contact points. Pin 87: This is usually a 12-14 gauge wire that will go from the relay to one side of the connector on coolant fan motor. The other side of the connector on the motor will go to ground.
-- Edited by 67Poncho on Thursday 26th of July 2012 01:45:13 PM
norontcan wrote: When I fed the switch directly from an always hot terminal everything appeared to work. Still sounds like I'm missing something.
It is just a regular 5 pin relay... Generally a 30amp rating.
It's purpose, in the most general terms I can, is to allow a low current switch and wiring to turn on a "switch" for a heavy amperage drawing device..... The switch being the relay....
To put it an other way, would you want to run heavy wire from your battery, inside to the dash of your car, to a switch and then back out again? Without a fuse at the battery, if anything were to happen to the motor, the wiring will cook all the way to the switch and back out... Plus, if the switch is not heavy enough, it can also melt and catch fire!!!
With the relay, you can have a little toggle switch inside of the car instead of a giant monster of a switch that will be capable of handling the current drag!
And as discussed in an earlier thread with starter issues in our cars, we can use the relay as the high draw switch activated by the ignition switch instead of the ignition switch. The ignition switch becomes the low current switch.... I had this issue with 2 of my cars Sunday past and I had to use a screwdriver to get them to crank... Many GM vehicles have been doing this same thing since the late '90's....
-- Edited by 67Poncho on Thursday 26th of July 2012 01:59:40 PM
also make sure you have the fan set up as a "Pusher" as it's on the frt. of rad. I've set the 52 up this way & have Thermal switch that turns fan on at 200F or I can do it 'manually" with dash switch if I want it on "sooner"
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Some times I wake up GRUMPY, but today I let her sleep in !!!!!!!!BLACKSTOCK Ont.
So let's see if I've got this right. 1) buy a relay 2) wire the keyed hot from the fuse box thru my newly installed dash switch to #85 on the relay 3) ground the relay or will this be done thru the mounting screw when I fasten it to a metal member? 4) run a heavy ( 14 or 16 guage ) from the battery to #30 on the relay but do it thru an in-line fuse or automatic reset circuit breaker.( I have a 20 amp now ) 5) run a 14 or 16 guage wire from #87 on the relay to the appropriate connection on the fan so that fan becomes a "pusher" 6) run a 14 or 16 guage wire from the other fan connection to ground
So, what the relay does is put a lighter draw switch into the main heavier line to the fan? The dash switch allows you to control the power to the switch in the relay?
So let's see if I've got this right. 1) buy a relay 2) wire the keyed hot from the fuse box thru my newly installed dash switch to #85 on the relay 3) ground the relay or will this be done thru the mounting screw when I fasten it to a metal member? 4) run a heavy ( 14 or 16 guage ) from the battery to #30 on the relay but do it thru an in-line fuse or automatic reset circuit breaker.( I have a 20 amp now ) 5) run a 14 or 16 guage wire from #87 on the relay to the appropriate connection on the fan so that fan becomes a "pusher" 6) run a 14 or 16 guage wire from the other fan connection to ground
So, what the relay does is put a lighter draw switch into the main heavier line to the fan? The dash switch allows you to control the power to the switch in the relay?
I'm off to Car Quest to buy a relay.
1..Check.. 2..Check.. 3..Check.. As long as as pin 86 is grounded... Some relays with the metal case will ground through the mounting screw...Not the case here though! 4..Check.. 5..Check.. 6..Check..
A 14guage wire will be better than a 16 if you have, depending on the load that the motor will draw!
I only had black 14 guage wire so I went and bought red 14 guage. Used the red to wire up the fan and black ( less conspicuous ) to wire the switch and relay. Got it all done and it appears to work as intended.
Thanks to everyone for your time and patient guidance. I guess an old dog can still learn a few things.
i was offered a 5 pin relay with a #87 and a #87A terminal. Similar to the one in your blue pic.
So how does this work? 1) with no power thru the switch to the relay 87A is hot - with power to the relay 87 is hot. That is it flips back and forth depending on switch position or 2 ) with power thru the switch both 87 and 87A become hot allowing the use of 2 accessories.
i was offered a 5 pin relay with a #87 and a #87A terminal. Similar to the one in your blue pic.
So how does this work? 1) with no power thru the switch to the relay 87A is hot - with power to the relay 87 is hot. That is it flips back and forth depending on switch position or 2 ) with power thru the switch both 87 and 87A become hot allowing the use of 2 accessories.
Pins 30 and 87A are as one when the relay is de-energized and when the relay is energized, pins 30 and 87 are as one... Yes, you can operate 2 separate devices depending on application, shutting one down or turning it on with the relay pin 87A.
And, just remember, you can operate any relay by either a 12v positive or negative source... In your case, it would have still worked if you had used a switch to ground instead of switched 12v positive. Just reverse the polarity of pins 85 and 86.... This was just the schematic I found at the time!
You have me thinking this morning of a project I will be working on where I will have to piggy back 2 relays and a turn signal flasher... But before I disclose, I will have to make sure it will work!!!
-- Edited by 67Poncho on Friday 27th of July 2012 08:31:21 AM
I only had black 14 guage wire so I went and bought red 14 guage. Used the red to wire up the fan and black ( less conspicuous ) to wire the switch and relay.
Actually, not less conspicuous but proper!!! I am a stickler when it comes to proper wiring colours for battery positive and ground... Nothing and I do mean nothin' chaps my a$$ when I see other peoples wiring under the hood of a vehicle and they have a red wire going to ground and a black or any other colour wire in the book feeding 12v positive! Or, one colour feeding everything! Try and trouble shoot that rats nest!!!
That's why I made RED stick out in bold and in the colour red!!! (lol)
