[Mk2] [NA] RAD FANS on all time.

[Zeppozen]

1991 3SFE Rev1

both Fans on all time.

Just changed Rad , complete with sensor.

Fans still on.
OK there is a remote possibility that both sensors are duff. ( how do i test )

but more likely to be other fault from what i have read on here.

Any ideas ?

NO aircon.

[Donato]

Did the car have air-con at some point?

There is an air-con connection in the frunk where it's re-gassed. If that's removed the radiator fans are on constant. It's a possibility of a wire being caught or cut.

[shinny]

Just changed Rad

I read the title and that was going to be my first question!

complete with sensor.

That's almost certainly the issue! The aircon and non-aircon sensors are different. Put the wrong one in and your fans behaviour will be inverted.

If your fans were working correctly before the rad swap then swap your old sensor into the new rad

NO aircon.

both Fans

Odd... generally, non-aircon cars had one fan and aircon cars had two. (What matters is how it came out of the factory - not whether you've stripped the aircon out since)

[Zeppozen]

wow quick reply.
Thank you.

rad fans on all time before on old rad and old sensor.

Rad fans on all time on new rad and new sensor it came with.

1991 rev1 3 3SFE. absolutely no idea if it ever had aircon or its history from new.

How can i tell difference aircon sensor from none aircon sensor ?

Im sure i saw a diagram for aircon on frunk fuse box, but thats prob standard issue all cars. ( must check to see if relay in there).

what is "re gassed " ?

would buy correct rad sensor but obviously dont know what type to buy now LOL.

re broken wire ..so i take it thatany fault in control system will default to rads on.

Defo twin fans and standard wire / plugs for such.

[shinny]

Ways to tell if the car originally had aircon:
1) A/C and ECO buttons above the interior fan switch
2) A/C lines (see the filling points above the PAS fluid reservoir - http://www.mybluemr2.co.uk/Rev3/Aircon/4.jpg)
3) Two rad fans

The other thing to do is take a multimeter to the old sensor:
a) If it's a complete disconnect between the pins then it's a switch from a non-aircon car.
b) If it's got zero resistance then it's a switch from a non-aircon car which is stuck on.
c) If it reads anywhere in between then it's the sensor from an aircon car.

I would expect you'll find case (a) and you need to order a sensor from an aircon car. I'm not sure if this is different for the earlier cars compared to the rev3 I did it for.

[Zeppozen]

ahh.

Thank you for this.

I will have a look. ( i defo have no A/C switches on interior )

Try test of old switch.

POWER STEERING ?? what is that ...i have old school raw feel partially assisted

I spend a while going through this discussion which goes so deep into the diagnosis my brain hurt but did give insight of your advice.

http://www.mr2.com/forums/threads/55907 ... diagnosing

Had a mild brain wave to replace sensor with normal type on most cars and just run a seperate live to it and fans creating a simple thermostatically controlled system. ( i.e taking A?C part out of loop )

an aside. I was going to put Halfords advanced anti freeze in, but just seen it is now Organic. confused on which to put into car now . Organic or non organic.
But thats another subject.

Thank you again.

[Peter Gidden]

3S-FE will not have had a/c.

Sounds like temp switch in rad is unplugged or has failed. Or temp sensor from a/c car has been fitted instead of a non a/c switch.

[shinny]

3S-FE will not have had a/c.

Sounds like temp switch in rad is unplugged or has failed. Or temp sensor from a/c car has been fitted instead of a non a/c switch.

I was about to correct you, but looking back over the BGB for the non-aircon system you are absolutely right! The temperature switch does the reverse to what I thought it did.

http://shinny.co.uk/toyota/MR2_SW_1993_ ... /radel.pdf

My money is still on it having the non-aircon part in. What car was the donor radiator from?