Black Beauty

ok...my single fan is setup to run full time...thats how i bought it. instead of playing around with getting it back to stock....can someone please tell me how to rig a switch to my interior...so i can turn it off in the mornings to warm up...and on long trips on freeway. thanks guys. Rick

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Rick
90 Camaro RS 305 TBI
400 small block, Hooker 1 3/4 super comp long tubes, Random Tech Cat, Hooker aero chamber cat back on the way!!
TH700-R4 with Trans-Go shift kit
MacEwen Motorsports White Gauge Overlays
K&N Filter Charger (wooohooo)
GTS Headlight and Taillight covers
5% Limo Tint all around
Classic White Chevy Bowtie sticker on rear window
www.geocities.com/esvalenz

Man if my camaro were a rice-rocket all those mods would give me what...easily 50-60 hp!!!

Tim Burgess

There are three things that normally control the cooling fan in the factory setup. The A/C selector switch (cooling fan on when in the NORM, or MAX positions), the pressure switch on the A/C liquid line (closes above 232 psig), and the coolant fan switch in the passenger side cylinder head, which closes above 238 F (way too high, in my opinion). All of these controls ground the dark green / white wire going to the fan relay, to turn the fan on. If you hook up the fan relay to just your manual switch, you must also make sure to turn the fan on when you use the A/C, or the head pressure at the discharge of the compressor will skyrocket, if there is no air moving across the condenser, & trip the high pressure cutoff switch on the compresser. It would probably be better to hook the system back up to function as it was from the factory, but buy a radiator mounted fan control switch (from Pep Boys) to turn the fan on at a lower coolant temperature, if the A/C is not in use.

Tim

Project 92 RS

I did exactly what ur trying to do. All I did was splice into the Dk. Green wire running to the fan's temp sensor. I ran that new wire into the interior through a grommet in the firewall, then to a basic on/off switch, which I mounted in the ashtray. This is the trick though, you need to run the other terminal on the switch to a ground. I used part of the E-brake mount. This gives you a choice of: 1. In one position, I call this one "on", the fan will stay on all the time as long as the key is in the run position, or 2. With the switch in the other position, I call "off", the fan will work normal. With the switch in either position, both the a/c and defroster work normal. Meaning that even if you had the switch "on" and the a/c on and then decided to turn the rigged switch "off", the fan would stay on because the a/c is on. I did all this because my temp sensor went out and I didn't want to go thru the trouble of replacing it. With this setup you just have to be more observant of your temp gauge. Hope this helps.

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92 RS 25 ann. ed. bone stock.
Many mods to come.

92 RSS

I did this with a dual fan setup. I bought 2 relays (20 or 30amp) and 2 on/off switches and installed them under the cig lighter. There's a little panel there that pops out. And labled them fan #1 and fan #2 with on and off. Works great and looks cool. But don't forget to turn them off.

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92 RS
350
Street & Performance MPFI
TFS heads
Crane Rollers
MSD Digital 6 Plus
24lb injectors
ZZ3 cam
Edelbrock Headers 1 5/8
3" Exhaust
Hi Flow 3" Cat
stock T-5
stock rear 3.08
koni yellow adjustable front
twin turbo glass hood
T-tops
Auto Meter Ultra Lite Series 2 5/8 gauges
Color: Teal Green

Ski89Z28

Black Beauty,
The type of relay that Tim is talking about from PEP BOYS is an adjustable "Hayden" fan relay switch, this is what I have since my 2nd fan sensor broke and I didn't know about it(long story). It can control 1 or 2 fans and you can adjust at what temp, to some degree, you want the fan(s) to turn on and off, this way it eliminates the need for a switch. It also has a wire that you can attach to the AC so when you run the AC the fan(s) will turn on automatically. It comes with instructions and wiring diagrams and is fairly easy to follow. One thing is I would solder all wires cause cripping connectors will rust after awhile and then the fan won't turn on!
If you do use a switch to turn on/off the fan make sure it is rated at 20 amps or more. Also try to run the ground wire (usually black) thru the firewall to the switch the to the chasis ground. This way if this wire would every short to the firewall or chasis it would only make the fans turn on. If you did it the other way, run the +12V line thru the firewall it could short and sparks would be flying and maybe nothing would work!
One last thing the Haydenfan relay cost around $40.00.

Good Luck

Stuart Moss

I disagree with the statement If you do use a switch to turn on/off the fan make sure it is rated at 20 amps or more..

Unless you are switching the fans directly (not using a relay), which should not be done for various reasons, any switch capable of switching 200-300mA (0.2-0.3 amperes) will be just fine. Most toggle switches on the market today can easily switch that amount of current.

A relay only needs about 100 – 300 mA (0.1 – 0.3 Ampere) of current, or about the same current as a small light bulb (a 194 draws about 275 mA as 13.6 V).

A factory electric fan on my ’91 Z28 draws about 21 Amperes at 14.0 volts for a start contidion, and about 8 Amperes at 14.0 volts during a run condition. Since all of this current is handled by the relay, the only consideration upon selecting the current capacity for the switch to turn the fan/relay on/off is the current draw of the relay, almost all of which are well under one ampere.

I personally prefer the minature toggle switches, most of which are rated between 3 and 6 Amperes as 125VAC. They take up a lot less room and look professinoal.

//Stuart

Ski89Z28

Stuart,
Not to flame you but first I've been in electronics for 20 years.

I think you are mixed up on what the relay draws as to compared to the amount of current it can handle.

Next your right that the RELAY draws about .2 - .3 Amps but the fans will draw over 20 Amps on startup.
Now if you read my previous post I put the switch on the ground from the FAN! That means the current going thru the fans will also go thru the switch to ground! That is as you said 21 Amps at startup and a continous current of around 8 Amps. Now with the "HAYDEN" relay you cannot put a switch on the wire that energizes the relay(coil/inductor), which you said and I agree draws .2 - .3 Amps, cause it is encapulated. Therefore, the 20 Amp switch on the fan ground.
Now a lillte schooling on relays. There are 2 currents going into a relay.
1.) The inductor (sometimes called coil)in the relay uses little current like you said, .2 - .3 Amps maybe even less but that is not important. This when current goes thru it will pull or close a switch to another current line for a device, this being the fans. You can use your mini toggles on this inductor circuit ONLY.

2.)Now this circuit for the fans in the relay has a much heavier wire since it will have currents up to 21 Amps, at times, when the above is engerized.

Most people put switches in the path of the current flow from the fans, either the +12V or the ground, since they do not know that much about electronics.
If you do put a switch on the inductor (coil) of a RELAY like you said it is a much smaller current draw. Although a 3 to 6 Amp at 125VAC is okay to use I would always use a switch that is rated to DC currents and Voltages.

One last thing, have you ever seen the relays in our cars for the fans? They are huge! And I bet that the "current capacity", as you put it, is NOT rated at 1 Amp. More like 10 Amps. Just go to a Radio Shack and ask for a 1 Amp rated relay and see how small it is.

Tim Burgess

As Stuart has indicated, it does not make any sense to place a high current capacity switch in series with the fan motor ground, when there is already a relay switching the fan motor load current on the positive side, that may be controlled through a low current path. Also, a switch in the fan motor ground wire would realize an "and" function with the other relay on the positive side of the motor, when, in fact, an "or" function is required. Therefore, a high current switch would not be necessary to control the fan, in any case, in this application.

The Hayden module is actually capable of grounding the coil on the factory relay. If the relay in the Hayden module is removed, a spade terminal may be inserted into the relay coil socket that the module grounds to energize the relay. The wire from the spade terminal may be connected to the ground side of the factory fan relay, and will function in an "or" configuration with the other devices controlling the ground to the coil on the fan relay. I have a module connected in this configuration on one of my Camaros.

Stuart accurately indicated the current draw of a factory relay to be less than an ampere, and the current "capacity" of a "switch" to control it.

A switch with a DC rating is not necessary for DC applications. A switch is typically derated for AC operation over DC. Therefore, the DC current capacity of a given switch with a current rating specified at an AC voltage would exceed the AC current rating.

In any case, the factory relay contacts must be rated at > 21 amperes (not 10 amperes), due to the inrush current of the motor stated.

Also, Pep Boys carries a 180 F non adjustible radiator mounted fan switch that's a bit less expensive than the Hayden adjustible module type.

Tim

Ski89Z28

Tim,
Thanks for trying to clear this up but I was aware of what Stuart was saying about controlling the relay instead onf the fan. And yes in his config the fan ground switch is NOT needed.
I never thought of removing the relay of the Hayden module and using a spade terminal in your config, pretty neat!
I also agree that Stuart accurately indicated the current draw for a relay. However when I posted my first post about the switches Amp rating it was for MY configuration and in that config you needed a >20 Amp rated switch. And I understood that he was saying that I should have used a lower rated switch, which I couldn't in that config.
Now Stuart's and you way is much better, lower current, but I was in a rush and didn't have a manual so I did what I saw was the best and fastest way at the time. Also my whole fan relay system was really screwed up but that is another story.
I hope I didn't ruffle too many feathers. But we are here to tell our stories and learn from others and I learned a little here also.
Thanks
Mike

Tim Burgess

No feathers ruffled.....

Tim