AFCO Heat Exchanger Help!

[rjm-1]

Hey guys, I'm trying to figure out exactly which wires to tie a switch into in order to turn the fans on and off without affecting the operation of the circulating pumps. I really don't want to pull the whole front end off again if I can help it. Ideally I'd like to cut into the ground wires and utilize a switch under the dash.

I know there are two black wires and two grey wires that are grounded to the top of the radiator support. But I can't see which ones are for the fans only (if either of them).

Can someone tell me exactly which wires to cut into so I can turn my fans off when I don't want them to run? :??:

 

[Van@RevanRacing]

Cutting into or splicing the ground to the fan (black) or the ground to the relay (grey) will accomplish your ability to control the fans with a switch.

Van

 

[rjm-1]

Thanks for the reply Van! So connecting the two blacks (tied together) to a switch to ground will control the fans only and let the pumps work whether the switch is on or off?

Cutting into or splicing the ground to the fan (black) or the ground to the relay (grey) will accomplish your ability to control the fans with a switch.

Van

 

[rjm-1]

Okay, Just ran a test to put a switch in between the black ground wires on the top of the radiator support and ground. Worked perfectly. Pumps still run and fans are controlled by the switch. Now to find a place to put the switch inside the car!

Thanks for the help Van!:banana:

 

[brandonflood123]

not to thread jack, but is there a possible way to hook up kinda like a turbo timer to the fans and stuff, so after you turn the car off it will keep the fans running for a short period of time to keep cool?

 

[Black Sex]

Could you add a thermostatic switch for that?

 

[KRS]

I think you would be safer switching the relay ground rather than the fan ground, less curent draw on the relay wires.

 

[rjm-1]

I already cut into the black wires. I could swap them to the relay ground if it really makes a difference.

Van, can you weigh in?

I think you would be safer switching the relay ground rather than the fan ground, less curent draw on the relay wires.

 

[SCGallo2]

I ran a bypass switch, 12V trigger to the relays, to energize the pump and fans on demand, even with the ignition off. I mounted it inside the center console on the e-brake adjustment access cover and had easy access to a 12V source in that location.

 

[BROK3N-SVT]

There is a write up in the how-to section for puting the pump on a switch. I did this before I even had a H/e. When I installed the H/E, and flipped my switch it already worked for the fans and pump. Anyways, why wouldn't you want the pump to run off the switch?

 

[Van@RevanRacing]

I already cut into the black wires. I could swap them to the relay ground if it really makes a difference.

Van, can you weigh in?

You can do it either way however the fan motor doesn't have any current draw with the ground switched off because the fan has an open circuit. The fan can't draw current or amperes without load. They only draw when the ground circuit is complete.

 

[KRS]

The concern is the current draw when the fan is on, the fans probably draw somewhere in the range of 10-15 amps each. You would therefore need to run a switched ground circuit to support double that for two fans and a heavy duty toggle switch that would support switching a minimum 30 amp load. The best way to do it is to switch the relay, that is actually what relays are made for.

 

[rjm-1]

Both van and KRS seem to make good points. Not having an electrical background, not sure which way to go? I plan on using a small button rocker switch. Not sure what it is rated for, but probably no more than 15 amps. Should I get a higher rated switch? Or go with using the relay grounds? And if I use the relay grounds, what rated switch do I need?

Thanks for all the input!

 

[Van@RevanRacing]

Just go with the relay grounds. No sense arguing over it. There is no inrush current regardless of which ground is seized for switching which by the way is about 9 amps per fan inrush. (that's at start up, operating is less)

Look at it like a light switch in your house. When the light is on you have current flowing and the electrical company is billing you. When the light is off you have NO current flowing and the electrical company is NOT billing you.

Same basic principle here. Fans not drawing current, Fans not taxing your charging system.

 

[KRS]

I wasn't trying to argue, just a discussion over the best way to do it. You told him how to do it, I'm just saying which is the better of the two ways. Again this isn't about the circuit when it is not energized, it's about when it is energized. The same amps flow on the ground side of the circuit as flow on the positive side of the circuit.

The relay is an electric switch, for comparison purposes you could compare it to the solenoid on your starter motor (bit of an extreme comparison). The relay is designed to switch a high load with a lighter duty switching circuit.

There are always several ways to do things that will work, I think forums are great because you draw on so many people with different backgrounds. Cheers

 

[Van@RevanRacing]

I wasn't trying to argue, just a discussion over the best way to do it. You told him how to do it, I'm just saying which is the better of the two ways. Again this isn't about the circuit when it is not energized, it's about when it is energized. The same amps flow on the ground side of the circuit as flow on the positive side of the circuit.

The relay is an electric switch, for comparison purposes you could compare it to the solenoid on your starter motor (bit of an extreme comparison). The relay is designed to switch a high load with a lighter duty switching circuit.

There are always several ways to do things that will work, I think forums are great because you draw on so many people with different backgrounds. Cheers

No argument. You have your way of how you would do it and I have my way of doing it. Both are viable options with degradation IMO to any of the components.

 

[Van@RevanRacing]

I wasn't trying to argue, just a discussion over the best way to do it. You told him how to do it, I'm just saying which is the better of the two ways. Again this isn't about the circuit when it is not energized, it's about when it is energized. The same amps flow on the ground side of the circuit as flow on the positive side of the circuit.

The relay is an electric switch, for comparison purposes you could compare it to the solenoid on your starter motor (bit of an extreme comparison). The relay is designed to switch a high load with a lighter duty switching circuit.

There are always several ways to do things that will work, I think forums are great because you draw on so many people with different backgrounds. Cheers

No argument. You have your way of how you would do it and I have my way of doing it. Both are viable options without degradation IMO to any of the components.

 

[ZX6Ray]

Van's credibility vs. some random internet one-upper... Hmmm that's a tough one!

VAN FTW!

 

[KRS]

Van's credibility vs. some random internet one-upper... Hmmm that's a tough one!

VAN FTW!

Go back and read what I posted! Van suggested two methods to do it and I responded with what I felt was the better of the two methods. Do you know any electrical engineers, ask them how they would switch a circuit with a relay in it (they'd switch the relay +).

PS - really mature post!

 

[ZX6Ray]

Too warm out to play hockey? lol