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fan relay info for newbs


Shelby
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lately we seem to have the same old problem new guys can't read diagrams or understand what they see

so heres a quick simple test for the rad fan motors , tools need'd are a volt ohm meter and test lamp,and 4 inch of 14g wire with male ends , and this diagram, key off in these first tests

 

first test for power at the fan mtr connector unplug'd , only one wire will have power(use test lamp)

 

now test with connector plug'd in,, if the motor is good you will have power on two wires the in and power out, this is because the brushes make a connection thru the motor and out,,

 

still only one wire with power the brushes are open and the motor is no good

 

ok you have power to and out of the motor, go to the relays

unplug one relays, install jumper as shown in the pic,, the motor for that connector should turn on and run at a good speed when jumper is incertd

 

if it runs slow, check the ground wire connection #1 it's on the fender near where the relays were attatch'd ,clean terminals and tighten the screw ,

still don't run to speed, remove the jumper from the blk terminal and touch it to a good body ground,, if motor now runs you have a problem in the ground wire from connector to the ground point

 

or the motor it's self has a internal problem " tip" a motor with a poor internal connection will have a small draw while a good motor will have a prety good snap when you ground the jumper

 

after you test the motor to see that they run, it's now time to test the relay operation,

 

on each connector you see one blue wire with tracer,,this is hot with key on , and is the power to operate the relay

 

pluging in the relay and useing the test lamp on the relay close wire,,( green on #1 relay and blk/yellow on the #2 fan control relay )

 

touching the test lamp to the close relay signal wire should make the relay close and the fan run

if eather fan fails to run,,the relay is bad and needs to be replace'd

 

after you test each relay,, redo the test at the thermo swt on the bottom of the rad,, all you do is unplug the thermo swt wire and touch it to a good ground,, if the wire is good the fan for that swt will come on and run at speed

 

testing the thermo swts can get to be a little warm on car,so the best way is to test them in hot water off the car with a thermomiter or temp sensor ,,a working swt will show "0" ohms when close'd and infinity when open, take note of the temp when it goes close'd

 

i hope this info helps a few of you , save a head or head gasket

if you remove the relay from the rubber boot you'l probly see it's all rust'd and corrode'd

 

http://www.26liter.us/gallery/albums/userpics/10009/normal_rad_fan_test.JPG

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Not sure if this is relative, but both our cars have the low temp and high temp triggers to the relay spliced together so that all the fans come on at low temp. Of the 4 cars I've done this to, all 4 ran substantialy cooler after the mod.
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it's reliative in the fact that this mod gives you only one thermo swt working at a time , all fan run funtions are now working off the low temp swt,, the high temp swt is working as a back up in case the low temp swt fails , down side is all fans will run

i personaly like to run the small fan all the time and wire the large fan to the low temp swt and the high temp swt,,this gives a back up in times when the engine needs the extra cooling and has a back up in case the low temp swt fails :wink:

 

thanks for the reply Mark , but i was first trying to get them to test the fans to make sure they run,,they need to do that befor going to other mods on how to turn them on

 

OH one more thing NEVER put toggle swts on fans ,uinless it's only a back up and only on the relay ground signal side

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Alo it's over kill to run all fans all the time, with a properly working clean radiator it's not nessarry to run them all, if it takes all fans runing to maintain cool temps the rad is not working as it should . as i said i like to run the small fan and keep the larger fan on the thermo swt as a back up,,but the thermo swts must be in working order,,as a safty feature you can wire in a on-off swt on the thermo swt ground wire to turn on if and when you want reguardless of coolant temps , but keep the factory wireing there and working for the other fans
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I understand what you're saying, Shelby. I knew all my fans worked but what started the whole thing was a bad high temp switch. We wired it to bypass that switch, and not only did the car now not even want to try and over heat, but it ran cooler at all times- low temps too.

 

 

Since then, I did it to a few more cars and had great results. Cars that once were getting up to 2/3 or 3/4 on the temp gauge now never get above half, ever- even idling in traffic on a 95 degree day.

 

 

Not saying it's the "right" way to do it, but we had good results.

 

 

 

Oh, and you're right about setting things up on toggle switches and such. Two of the cars I've done this mod to, HAD to be done because the factory wiring was thrashed due to having toggles and relays installed. One of them even had a "kit" That was made by TEP I think that was supposed to help. What a POS!. The guys lucky his car didn't burn down from that piece of junk. Not to mention after the mod his car wen't from running regularly at 2/3 on the gauge even with that "kit" to running at 1/2 with the mod I did. It cleaned up the engine bay, helped his cooling, kept his car from catching fire and was free. I'd be scared to see how much one of those "kits" from TEP cost.

 

 

Again,maybe not the "right" way to do it, but better than toggling stuff and re-running wires due to a bad switch. The only real downfall I see is that the fans may pssibly wear out slightly sooner as they are running more than normal, but IMO is a small price to pay to never see my temp gauge above half.

 

 

Of course, the radiator and fans are the important part. For instance my car and Kate's car are nearly identically modded, but hers always runs a tick higher than mine. My radiator and fans are probably in slightly better shape.

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