JCB250r

I have a 89 IROC Z And I am wanting to lower operating temp. It has the sensor in the front of the intake yellow and black wire and also the temp sensor in the head between #6and 8. fan turns on at 230 degrees to hot, but secondary passenger side does not turn on unless you turn on AC. what sensor do i need to get , also went to Advanced and tried to order the GP sorensen FS6 but they were calling it a fuelm pressure sensor Help me out please>.

ASE doc

The low temp fan is controlled by the ECM and should come on at about 220. The second fan is AC condensor fan and is also used by the ECM as a high temp fan. It should come on from high temp but not til about 240. The ECM uses the sensor at the front of the intake to read ECT. The sending unit in the head is only for the gauge.

Changing the turn on temp of the fans can be done by reprogramming the ECM or you can simply bypass the factory fan control. I have installed a few of the Be Cool fan controllers. They run about $40 and if youre good with wiring, you can use it to activate the fan relays so both fans run together.

To do this you connect the Be Cool fan controller to ground (instead of 12v as indicated in the instructions) then tap into the small green/white wire at each relay with the switched ground from the fan controller. You can now set the fan temp wherever you like.

Remember, the factory thermostat opens at 194 so if you want lower temp youll need to change stat.

JCB250r

My car has the Gauge temp sensor in the drivers side head but on the passenger side it has a lower sensor with a white wire looks like a knock sensor but above it has a single wire sensor with the same connector with a brown wire. I would like to make them turn on at the lower temp. I took my meter and back pinned the sensor in the front and at initial start it had 3.5volts and after it warmed up to 230 the the volts dropped to 1.4 and the passenger fan kicks on but not drivers side.

Ron U.S.M.C.

Try this = http://rodneydickman.com/catalog/pro...roducts_id=233 or this = http://www.mamotorworks.com/corvette-3-138-944.html As far as the FS6 is concerned I beleave its TFS6 . I looked at that switch and it dose not look as if it has the same connection as the stock switch.

ASE doc

It sounds like your fans may be working normally. I apologize for my mistake. The low temp fan is also the AC condensor fan. The fact that it comes on with AC on shows that the fan and relay are fine. It is turned on by the ECM when voltage from the ECT sensor at the front of the engine drops low. From your description, it did this when you were testing. On datastream, using a scanner, I would expect to see this fan commanded on at about 220.

The high temp fan is controlled by the switch in the pass side head. It wont come on til 240 normally. You can make both fans run off the temp switch in the pass side head and can lower temp by using the TFS6. You will need to wire both relay control circuits together. At the relays this is the green and white wire as I mentioned before.

If you simply change to the lower temp switch, only the drivers side fan will run. The ECM will never command the pass. fan on because ECT will never get to 220. You want to make both fans run off the lower temp switch.

JCB250r

Thanks for the info so the passenger side sensor single wire is for the passenger side fan and turns on at 240 and the 2 wire yellow and black in the front of the intake water jacket is what turns on at 230 still to hot for me. What i dont get is all these sensors are single wire for the secondary passenger side. So if i change that It will turn on at a lower temp.

ASE doc

Actually, I think the passenger side fan is the primary, low temp fan and the drivers side is the high temp fan. But no matter really. The point is, it appears that at least your primary fan is working normally. We dont know about the high temp fan because it only comes on at 240 when your engine is close to overheating. You can test the fan and relay by grounding the wire to the temp switch in the passenger side cyl head. This should cause the high temp fan to come on.

The low temp fan is turned on by the ECM according to coolant temp as measured by the sensor at the front of the motor. This is not a switch but a sensor. The coolant temp info that it provides to the ECN is used for injector pulse corrections and other functions. You do not want to try to manipulate fan function by messing with the ECT sensor.

As I said before, you can change fan on temp by installing an aftermarket fan controller as I described above. Or you can modify your fan control wiring so that both fans are controlled by the fan temp switch as I described in my second post. Then you can switch to whatever temp switch you prefer to determine fan on temp.

The factory fan control in the 3rd gen is set to work with the vehicle's emission controls to reduce pollutants. Running the engine at 210 degrees reduces the production of hydrocarbons. The OE determined that the affect on peformance was negligable.

I can understand that you dont like how hot the engine runs. I didnt like mine running that hot either. Several customers have also had this complaint. The BeCool fan controller has worked for a few of them and it allows adjustment of the fan temp just by turning a ****. I have used the lower temp fan switch for others. I myself have ACCEL DFI with programmable fan control. When you decide what to do with your fans, youll want to also change to a cooler thermostat to work with the cooler fan temp. The temp you choose is up to you. Fan on temp should be 20 degrees higher than thermostat temp.

JCB250r

So I finally got to work on my car again and while it was running grounded the passenger side temp wire and both fans turn on. Its almost hot enough down here in the South to leave it like this. what do you think. If not I guess i will get the fs6 sensor 160 to 180 sensor for it.

ASE doc

Get the switch bro. Dont be that guy whos fans toast on him in rush hour traffic 50 miles from home. Good job finding the solution.

JCB250r

I got the switch and both fans turn on at approximately 190 and even in traffic stop and go does not go over 220. Fs6 GP sorensen no longer available. went to Autozone and got the switch for 18.98 Part number 35946. Thanks for the help.

ASE doc

Love it when a thread ends in success.

IROC#1

How do you install the switch? Is it a relay? Any special wiring or is it plug and play?