T88Rx7

im having some serious fan situation, need some electrical expert help here!!!! i just installed my new motor in the car. as im doing the coolant part my fans dont seem to come on, and my coolant guage isnt going up, but i can read my temps via PFC commander. im not trying to wait till the car reaches 200 some degrees as some people say thats the temps they come on. so i tried this fan mod here http://rx7.voodoobox.net/howto/fanswitch/fanswitch.html and i grounded the 2 wires and the fans still doesnt come on, and i know the fans work because i wired them up direct and they spin. ANY IDEA GUYS!!!!

P.S. I DONT have a datalogit

c00lduke

Do you have the water temp sensor on the the rear iron hooked up? Do your fans come on when you turn your AC on?

T88Rx7

no a/c, the wire is connected to the temp guage sensor above the oil pressure sensor.

redsuns3838

are u sure the fans are getting power?
maybe a connection is bad. bust out the multimeter?

BOTTLEFED

iTrader: (1)

check the thermoswitch on the back of the W/P housing - check the wires and the connector, it can get mixed up with the fuel temp sensor since the connectors are the same (green)

scotty305

iTrader: (2)

If grounding the relays isn't turning fans on, it's possible the relays aren't properly connected to power or ground. Can you hear the relays click when you ground the 'fan mod' wires? Double-check your 60A "COOLING FAN" fuse, and if that doesn't fix things, it's definitely time to get your multimeter.


-s-

T88Rx7

the thermoswitch is working fine, thats how the PFC gets its temp reading, i wouldnt be able to imagine fuel temps going up to 210 F.

When i grounded out the relays i didnt here them click. Im going to have to go out and get a multimeter... damn these electrical systems where to start...lol keep you guys updated, and if you guys have any other ideas please let me know

scotty305

iTrader: (2)

Start by checking your fuses again, most of the relays share the same fuse. If your relays aren't clicking, that's because they're lacking either power or ground. Check all four relays, because they don't all share the same power and ground. If any one of them works, post back here and we can continue to rule things out.


To activate Relay No.1, connect the thin Violet/Pink wire to ground. This relay doesn't have power unless the ignition is the ON position.
Relays No.2 & No.4 are tied together, they'll both be activated with the thin Green/Black wire.
Relay No.3 turns on with the thin Blue/Green wire.


For some more info, and a nifty colored diagram, see this thread: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/2-trigger-cooling-fans-462760/

-s-

BOTTLEFED

iTrader: (1)

actually the PFC reading is from the water temp sensor, not the thermoswitch
as implied by the name thermo"switch" it turns the fans on at a predetermined temp and off at another like a switch
the thermoswitch is the one above the water temp sensor with a green connector

T88Rx7

the pfc does get its coolant ready from the thermoswitch, because when i discoonnect it the temp reading on the commander shows ____ instead of a number reading...

all relays are getting power, with ign on. but when i only ground the relay 1 with the violet/pink wire the fans come on and relay clicks, so that good... which relay is that for? all the other relays dont click when i ground them or turn on the fans, so im guessing the relays are bad or has bad connections.

another question is would you think its safe to instal a on'off switch to relay one by grounding the violet/pink wire thru the switch? reason for me to do this is to get the fans to come on earlier till i get my datalogit.

scotty305

iTrader: (2)

When people say "thermoswitch" they're referring to the one-wire sensor that acts as a thermostatic switch. When the coolant temp is above 108C (226F), the thermoswitch closes, which will increase the fans' speed if they're already on.


When people say "thermosensor" they're referring to the two-wire sensor that acts as a variable resistor. The resistance will change gradually with temperature, allowing the ECU calculate the exact coolant temperature. Now here's the confusing part: the FSM isn't consistent about its labeling of these two devices. Double-check this thread, there are some good descriptions there. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/name-sensors-dealing-coolant-game-594138/





Back to your issue:
Relay No.1 is only controlled by the 'Heater Control Unit,' which is the A/C and fan control switch on the dash. You've gotten it to work, so that proves that your fuses are OK. You should be able to turn the fans on by turning the AC on and the cabin fans. When the 'AC' light is lit, Relay 1 should be activated also. This should function as your 'fan switch' for now.


The relays work in conjunction with each other: by itself, Relay 1 will turn the fans to low speed. Without the other relays, you won't get medium speed. Another thing: the ECU doesn't have any access to Relay 1, so your Datalogit won't turn any fans on at all until you fix relays 2, 3, and 4.



The next thing I would do is check Relay 3 again. Relay 3 is activated by the blue/green wire. The one-wire thermoswitch grounds out the blue/green wire, and that will kick the fans up one speed. Relay 3 won't turn the fans on by itself, so make sure you're activating Relay 1 first.


If the other relays aren't clicking at all, it's possible that they need to be replaced and it's also possible that they have a wiring issue.


-s-

T88Rx7

when i take out the green sensore above the black one, the commander shows no reading, so i guess that would be where it is getting its temp reading from

so your saying i have to ground relay 1 (a/c relay) and ground relay 3 with blue/green wire to see if relay 3 works/ clicks?

also in order to turn on relay 1 via a/c botton i have to have the a/c relay that goes in the front of the car thats is in the black box inline with a few other relays correct?

scotty305

iTrader: (2)

^^Yes, you'll need all the fuses that run the AC and interior blower motors.


You're absolutely correct about the sensor that the PFC is reading from, I just wanted you to know that most people refer to it as the 'thermosensor', and there is something else called the 'thermoswitch.' The 'thermoswitch' has control of Relay 3 (grounds it out when the engine gets above 226F, and increases the fan speed if they're already on). It is one wire, and if yours isn't connected that could be an issue. There are some photos here: https://www.rx7club.com/3rd-gen-archives-73/fc-thermoswitch-fd-447606/

-s-

T88Rx7

yes i would have to get a relay for my A/C for the black box infront of the car, any ideas where i can just get one of these relays? does having the a/c compressor off the car effect the power as a driver to turn the A/C relay number one on via the A/c botton to turn on the fans?

p.s. good find on the thermoswitch upgrade from the FC