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electric fan switch wiring

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xj88superjeep

NAXJA Forum User
Location
NJ
Does anyone know if the positive lead for switching on the fan with the air on is the same wire that switches it on for the defrost? I am gonna be wiring up an adjustable e-fan control, and it says to jump into the same positive as the air conditioner, but I still want it to run when I use the defrost too. So is there a wiring guru that can help me sort it out before I start so I am not stuck with trial n error... I got the Hayden 3651 with the threaded temp switch that plugs right in where the factory switch is, but has it's own relay with an adjustable tstat/fan control. It does not help that they included the instructions for a DIFFERENT model, and I cant find a writeup on it. Should I relocate the location of the temp switch to somewhere else like the lower rad hose? I appreciate that most of you probably just use a toggle switch, but if there is anyone who has rewired the factory wiring to an aftermarket unit, could you share your wisdom?

THANKS! :worship:
 
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Yellow wire into the thermal switch (radiator temperature switch on the drawing) is power with the ignition on, the grey wire out from the switch is to the relay and actuates the relay.
The power to the relay from the A/C and defrost is a "T" with a diode so the power doesn't go the wrong way back into the A/C circuit. No problem.
Just wire in your switch to the connector before the OEM thermal switch.
 
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Thanks a billion 8mud! This should make easy work of the upgrade! You get full credit when I do my full tech write up of my cooling system upgrades. I have an all new stock cooling system that works great, and I am putting together an extreme duty cooling upgrade that renix guys with closed systems, AND open system guys can do. My goal is never going over 200 degrees in any conditions! Not in traffic, not at a stop light, not towing, never. That is while still using a stock rad, and a clutch fan/stock e-fan configuration! I want to show that we don't need fancy three and four row radiators with three Tarus fans with toggle switches on the dash to stay cool. (I'm not bashing those who have done the e-fan upgrades, because those work too)
 
hubs97xj said:
I tapped into the trigger wire for the Compressor itself- whenever the compressor kicks on, the fan kicks on.
Click to expand...

Is that using an aftermarket fan control, or did you just wire some type of fan upgrade to it? Dose it still come on with the defrost? The (wrong) instructions do say to tap into that wire, but I want to make sure it will still work when in defrost mode. I'm guessing it would, but I don't want to guess wrong.
 
Actually, if I do what 8mud says, I don't even have to bother the ac/defrost, because that will still work as the factory setup, and I am just jumping in before the factory temp switch with an adjustable temp switch to get the fan to come on sooner... true?
 
The difference between a/c and defrost modes has to do with the mixing doors and vents in the cabin -- there is no difference in compressor operation.

I tapped into the wiring at the compressor (same as hubs97xj) when installing a control unit similar to yours. I would use whatever wire is easiest to get to.
 
What I am wondering is this:

If I don't disrupt any of the factory wiring, I can skip splicing into the ac wiring because that will still function from the existing relays. So, the only thing my adjustable control unit will do is splice into the ignition signal wire prior to the factory switch, and splice into the existing fan connector while still leaving all original connections intact, circumventing the factory preset switch and triggering the fan at a cooler temp while not interfering with the operation of the factory ac/defrost relay. Am I crazy, or is this headed in the right direction?
 
xj88superjeep said:
with three Tarus fans with toggle switches on the dash to stay cool. (I'm not bashing those who have done the e-fan upgrades, because those work too)
Click to expand...


Make sure you have those wired right.At start up those fans pull as high as 90amps a piece!!:scared:
 
Then yes, I would leave the factory wiring in place, skip wiring to the compressor, and splice into the fan connector as you suggest, A convenient place to tap into ignition-on wiring such as the Hayden relay unit is the fuel pump ballast resistor (assuming the '88 has one). That is what I used when I installed a Hayden override control in my '93. There may be other equally handy spots on the '88.
 
I installed the Flexalite 31165 variable speed controller . In the instructions, it says to connect to the wire that triggers the compressor to kick on, so that whenever the compressor is running (AC or defrost), the controller signals my electric fan to run. One wire connection to the pigtail off the back of the compressor- all other wiring left intact.

I misunderstood your original post. I thought you were adding an electric fan, not just trying to force the aux fan on sooner. Just to clarify, are you wanting to keep the stock wiring connected to the fan, and use the controller to kick the fan on earlier?
 
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OK, as I was waking up this morning the little light bulb went on, and I said to myself, "Self, you better be careful with the wiring and make sure that if the factory temperature relay closes the circuit while the fan is already running, you get double power to the fan, because something bad will happen!" Since I am going to try to jump into the same ignition source as the factory relay, it really shouldn't matter if both circuits are closed because it is still the same power source, right? The only worry I have is the power lead going to the new control unit straight from the battery. I am sure this is just to power the unit itself, and does not lend any power to the fan, but hope someone could reassure me. Thanks!
 
I think you have it slightly backwards. The power lead straight from the battery to the new control unit is switched by a relay in the control unit and then goes directly to the fan. Current to power the relay in the control unit is provided by the ignition source. This is represents a minuscule current draw which is switched by the coolant sensor.

In any event you will have no problem with the parallel power sources to the fan. As stated above, I did the same thing with a Hayden unit about nine months ago except I got the unit with the probe that sticks into the radiator core. The existing factory wiring turns the fan on when the a/c comes on and the Hayden unit turns the fan on as the coolant temperature rises. There is no conflict when both sources provide current to the fan at the same time.
 
Pelican said:
I think you have it slightly backwards. The power lead straight from the battery to the new control unit is switched by a relay in the control unit and then goes directly to the fan. Current to power the relay in the control unit is provided by the ignition source. This is represents a minuscule current draw which is switched by the coolant sensor.

In any event you will have no problem with the parallel power sources to the fan. As stated above, I did the same thing with a Hayden unit about nine months ago except I got the unit with the probe that sticks into the radiator core. The existing factory wiring turns the fan on when the a/c comes on and the Hayden unit turns the fan on as the coolant temperature rises. There is no conflict when both sources provide current to the fan at the same time.
Click to expand...
Ahhhh! I feel my brain growing! Thank you for clearing that up! I will be running the wiring tomorrow, and I will let you guys know how it went. This is just a small step in the upgrades I have planned, but as you guys know, keeping the air flowing through the fins is paramount when you are talking "heat exchange"

Kudos to Pelican and 8Mud... :worship:
 
have 88xj ac doesnt work anyway, can i just go around all that and run wire from temp switch to e-fan? right now i pulled a different plug apart that has power and have the fan going whenever the rigs running. kinda wierd though i turn on the key and fan kicks for a second and then goes off until i start the rig, but it works.
 
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