Is wiring dual fans together up to the fan switch on the passenger side of the block so they come on at the same time a bad idea?

i hear the driverside fan only comes on when the ECM tells it to. Can u wire up that fan to the passenger one so it goes on according to what fan switch you have in the passenger side of the block? so they both run at once?

 

I'd use a heavy duty relay and appropriate wiring. Switch the relay through the ground using the fan switch and you'll be OK.

 

The passenger fan's fan switch should override the ECM based driver side fan anyways. With my stock chip and 200° fan switch, it should in theory start the passenger fan at 200° and then start the driver side at 223°.

But it doesn't. The driver side will always run with the passenger side.

 

I have dual fans that were professionally wired last year to come on at 220 on the temp gauge. Two Delco relays were put in by the installer. I monitored them just yesterday and they work perfect. Although I have factory A/C I still need a compressor but the wiring was set to accommodate the A/C related switch as well.

 

The A/C would run both fans at the same time regardless of the fan switch so yes, it is safe. The fan switch is also tied to the A/C fan request input. If a lower then ECM temp fan switch is used, the secondary fan will run and also ground the A/C fan request input making the ECM switch on the primary making both fans run without any wire hacking or, adding an aftermarket fan controller. Kind of expanding on what Reid stated, really, I guess.

This was not the case for 87-older dual fan setups, which you don't have.

 

Don't mean to hi-jack this thread, but what about us that have an 89 ?? (1989 IROC 5.7 stock).

My car, while driving runs (according to the gauge) at 160, when I stop, it goes up to 240 then comes right back down to 160. It has a 180 thermostat. When I have my a/c on it runs a steady 160 and needless to say both fans are running. This going up and down is frustrating when I'm going through a drive thru or something.. I'd like to run both fans, but afraid I'll burn one of them up continuously running or something not hooked up right.. The IROC's I've had in the past didn't have this problem.. any advise would be appreciated.. Stone

 

A simple 200/185° fan switch will solve what you're asking. At that point you would have the same setup as I do. (180° thermostat and 200/185° fan switch)

So in the winter time with Defroster off, your fans won't turn on until 200°. Good for heat. At that point both will turn on. In summertime, the same thing would happen unless you have the A/C on and the coolant temp is below 200°, in which case it would turn on your fans anyways.

What is happening right now is that your car will not turn on until the stock fan on temps. (223° for driver fan and 235° for passenger fan)

 

Cool (no pun intended), where can I find the 200/185 fan switch ? And to clarify, it goes on the passenger side head in the motor, right? Stone

 

If your temp climbs 80 degrees at a stop, you have another issue entirely imo than just not having the fan come on....my guess is your secondary fan isn't even turning on. You need to verify that your temp switches aren't stuck open which can cause a problem. I've always thought it goofy for GM to design one fan then the other to turn on. They should have come up with a better method at the time. If you want to run both fans and have 3 speeds for them, assuming your cooling system is in good working order, I can help you out. I just built a 3-speed harness for a member and I can put one together to allow you to run both fans at low, medium or high speed. PM me if you want info/pics.

 

Both fans do come on.. visually saw them, radiator and fluid are in good condition. I'm wondering if the gauge is accurate. Either way, I'd feel better if I could run both fans. The idea of the fans being variable speed is cool, I just want to try to keep my IROC as original as I can (except for my seats, they're 01 Trans Am seats and I LOVE them lol)
I'm in the hospital right now battling Leukemia, and my girlfriend is having to drive my car to work (100 miles round trip because her car is in the shop, and she's freaking out when the gauge starts to climb while she's in bumper to bumper traffic, we're in Virginia so it's a little warm out these days).. Thanks again.. Stone

 

Hypertech makes a 200/185 fan switch. I got mine from Summit. They're about $40. Part number 4028.

Correct. Passenger side between the 6 and 8 cylinder.

Stonehenge > Leukemia!

 

Reid, ran into a problem today. Outside temp was 94, was driving,a/c not working, tops off. Came to a stop light and temp rose from (A) to (B) then I got out of the car and saw both fans OFF. I tried to turn them ON by putting my a/c to MAX, nothing.. then Norm and still nothing so I left it OFF. I looked at my gauge and as soon as it got off (B) BOTH fans came ON. The temp rose to (C) and quickly dropped back down to (B), at which time the 2nd fan shut off. The temp went down to (A) and the drivers side fan shut off..

I was reading another thread and the guy stated that the primary fan is controlled by the ECM, and the secondary fan comes on with the fan switch located on the passenger side of the block. Is this correct..???? Stone

 

Primary fan with ECM and Secondary fan with fan switch, the other person was correct.

Take a look through my signature. It should show what to check if the fan(s) don't come on with A/C request.

 

Shouldn't AC use override both?

 

[quote=

Take a look through my signature. It should show what to check if the fan(s) don't come on with A/C request.[/quote]


Wow, what a great read. I really appreciate the help.. When I pulled into that gas station and saw my temp go past 230 and neither fan was ON, it was kind of disheartening. Then when I couldn't turn them on with the a/c I figured something bad was about to happen, not to mention ~ I was in the middle of a monsoon.. stone

 

It should. If a person is low on refrigerant and the system is cycling rapidly (and everything else is working properly), you could see a scenario where the fans

a) don't have enough high-side pressure to turn on the passenger fan
b) the driver side fan will be on/off for 15 seconds. So if the A/C cycles on while it's waiting it's 15 seconds during the off phase and then the A/C cycles off, it wouldn't trigger the fan on.

Could be a relay.