Was thinking about this for dual fan setup: One fan (passenger) turns on when my coolant gets to 220. The other (driver side) is supposed to turn on when the a/c is activated. Actually, that driver side fan does not do that in my car when I flip the a/c switch (bad motor). Anyway, would it notmake more sense to wire both fans up to the fan switch (aka coolant temp sensor in the block) ? I mean, if its hot enough to run the a/c, then wouldn't the fans be running anyway?

Have I gone wrong in my reasoning here? Would anybody with some electrical experience advise me if this can be done?

That way, you get the effect of cooling of both fans instead of one. Also, the passenger side fan (controlled by the fan switch @ block) sits right in front of the radiator (obviously, right?). But (and here is the point) on the opposite side of the radiator is the transmission fluid/oil cooler. So basically, the fan you need to cool your engine has a huge restriction right in front of it and the other fan is useless unless the a/c is on.

Am I right? Or have I miscalculated?

 

If you turn on the A/C before the engine has time to get to the 220*preset fan turn on temp, then the A/C Compressor pressure safety valve will discharge because the freon gas inside the A/C Condensor will get to a very high pressure if not cooled down in time. That's why the fan comes on when the A/C switch is on. It only takes a few minutes before the pressure gets to over 300 psi. I just wired my two fans to come on with the A/C on or fan switch because in the summer, I run my A/C almost everyday and even the first thing in the morning so the fans need to be on even though the engine isn't up to temp yet.

 

here is my setup..

factory cooling system.. 195 thermostat, factory everything.

my drivers side fan comes on at around 227... ecm preset
the passengers side comes on at around 237... fan switch

when my a/c is turned on both fans comes on.. no matter what temp


so what i did is that my normal engine temp is around 220, so no fans are on. but when sitting in traffic for a couple of minutes the temp starts to rise a bit so most likely the drivers side fan might come on when sitting around, and then starts the keep the temp from rising any more, and when really hot outside it needs some help brining it back down and i dont want to see it ever come close to 237. so i wired in a switch.

first i found the passengers relay, once found i looked for the tan wire, after i found that i jumpered into the wire and hook that jumper to the switch. and then to complete the circuit i ran the other wire from the switch and found a good ground.

so now i can turn the passengers fan on at anytime when the car is on.

 

GKK is correct. The AC condensor needs immediate air flow. One thing I always point out with both fans wired is this. You will in fact start to chew up the alternator faster. With 2 fans on and AC comp clutch and blower motor all running at the same time it places a very heavy demand on the charging system. Thats why the engineers don't do it. The alternators on these cars runvery hot under normal demand situations and placing more stress on the charging system will result in much shorter life.

 

ok...so what I am gathering is that you can wire;

a). both fans turn on when the a/c is on.
b.) both fans turn on when temp gets to 220-237
c.) a manual switch to have both fans come on at same time whenever you want.


I have a "cool fan switch" that allows the passenger to come on at 220 (instead of the hotter factory preset).

How can I wire both fans to work via the fan switch (when the temp reaches 220) and so that they both work when the a/c is flipped.

Do I just need to run a single wire that inserts on the (+) leads of both fans? And do I need a fuse between the wiring?

I removed my foglights this weekend to get better airflow this weekend. If I wanted I could run the wires that used to run to the foglights to the fans. That way, I would not have to mess with pulling the wires thru the firewall, and the switch is already on my console (foglight switch).

 

well when the a/c is on both fans should come on!! thats how the factory dual fan setup works..

my drivers fan uses factory preset which when the ecm detects around 227 the fan comes on....

my passengers fan uses the factory settings, the fan switch is stock so the fan will turn on if the temp ever gets to around 237.

all i did instead of buying a fan switch to turn that fan on earlier is i just installed the new switch to turn that fan on anytime i want..

but since you have the the cooler fan switch for the passengers fan and your using the factory setting for the drivers fan you should be ok....

 

Now we are getting somewhere. OK, I have never ever noticed my driver fan working regardless of the temp or whether or not the a/c is on.

Just went downstairs, popped the hood started the car, turned the a/c on. My a/c does not blow cool so I never use it anyway (no $$ for that right now anyway). But anyway, I turned the a/c on. I looked at the fans. Neither one was working.

But I do know that the passenger fan works when it gets to the fan switch temp.

 

ok sounds like you need to fix your a/c..

at first when i turned my a/c on the fans did not come on, i found out why.... it was because the a/c needed to be charged, once charged the the pressure switch had the right pressure and both fans came on.....

since you dont use your a/c much... you can switch wire that fan to the a switch and you will be set...

 

once you find the fan relay for the drivers side fan, should be near the drivers firewall..

you can take the relay off and work with the connector and jumper the proper wires and test things with a voltmeter.

 

gotcha...I figured it had to do with the a/c needing to be charged. Thats a whole differnet beast. I bought this car 4 months ago. It was spirng and I did not need a/c. Its my girlfriends dad's car. Supposedly, the a/c did work not too long ago. So hopefully its just an r-12 charge I need. I've neglected to take it in because I don't wanna be jerked around by a mechanic.

So now the question is, do I wanna run a manual switch for both or just the driver side fan. Since I got the cool fan switch on the other side, I'm tempted to just run that manual switch to the driver side fan. Its too bad that that foglight wiring won't work out. That would have been sooo easy.

 

just wire the drivers fan to a switch. because you already have the passengers fan coming on earlier from the cool fan switch.

what you could do is run the wire to the foglight switch and just just trying different pins on the switch untill the fan turns on when the key is in the ingition on turned to the on position..

that would work!! so you dont have to worry about finding a switch or a place for it...

 

It appears to me that you need to FIRST figure out why your drivers side fan doesn't work at all. That fan is controlled from the ECM. Check your relays, and fusible leaks. If yu dont use your AC, don't worry about it, probably just needs a recharge. Turn-on temp depends on the car and year. Mine was set for on at 226/off at 220. The heavy duty fan switch is set for on at 238F. Too hot for my likes.

Here is what I did. I can set the primary fan turn-on to anything I want, since I do my own chips. Right now set for on 185, off 179.6. But before that I wired in 2 manual fan control switches, one for each fan. Installed a Hayden thermal switch in the rad near the top hose. This is supposed to flip on at 185 off 170. I could use this to turn 1 or both fans on, or I could just turn both on and leave them on.

Now that I do my own chips, I just let the Hayden control the sec fan. If that fails the stock (238) switch should work. I may up the primary fan turn-on, since I just put in a 180 Superstat.
(Was running a 170 thermostat)

You really don't want both fans on alot if you can help it, they do draw lots of power. If you can keep it cool with 1 fan, then you are better off. Also heard they create drag when running as you are cruising down the road. (Myth or fact??) If you use AC alot, then your fans must run, as stated above. No getting around that.

Just my 5cents worth!