another fan question HELP!

importkiller

Registered User
ok guys i've completed the engine rebuild on my 90 sc she runs great i just have one nagging problem. My damn fan won't come on. i've tested the fan it self it works properly. i've also change both temp sensors. (now my temp guage is working. ( THANKS GREG) now my fan still doesn't come on i unplug the coolant temp sensor fan comes on along with check engine. i also did notice that it doesn't come on when i run my a/c.my question is: WHAT ELSE CAN I CHECK TO FIX IT? that fan issue is the only reason why the car hasn't gone to the painters and on the road.
 
ok just checked my ircm both the wires going to the fan look like the voltage are low b/c test light was very dim. i jumped the wire fan cuts on if this will help?
 
I would try replacing the coolant temp sensor (the one you are unplugging to make the fan come on) but that doesn't really explain why it's not working when you turn to AC/Defroster on, so it could be a problem with the ICRM (relay module).

You could try cutting wire #14 on the module which should turn low speed fan on whenever the car is running. If that works then the relay module is probably okay.

David
 
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David Neibert said:
I would try replacing the coolant temp sensor (the one you are unplugging to make the fan come on) David

i've already changed it twice. so what you are saying #14 should run fan on always. do i hook it up to anything?
 
If the relay is working correctly, breaking the connection on wire #14 turns on the Low speed fan and yes it will stay on (whenever ignition is on) unless you reconnect the wire using a switch or wire in a thermostatic controller and a relay.

I don't have a wiring diagram for running only the low speed fan, but here's one for controlling both the high and low speed fan functions without affecting the EEC's control over the fans if you turn the settings up too high or want the fan to come on with the AC.

fan%20relays.jpg


David
 
that great! just one more question. if i disconnect wire 14. is it possible to have the high speed come on if i were to go 90 mph on the highway :confused:
 
Delta fast response temperature sensor

Take a look at this website: :cool:

http://www.dccontrol.com/

With my MP FMIC i did NOT like the (1) one speed fan.
Maybe this can help with your factory fan.

The Delta variable speed fan control keeps the engine at
a CONSTANT temperature by regulating electric fan speed.
In other words, if the engine temp increases so does the fan speed,
and as the engine cools the fan speed decreases.

I had installed a Hayden temperature sensor and relay
to turn on the fan sooner because
FORD sensor/computer does not turn fan on until 210+. :eek:

The one speed fan would go full blast when engaged
by the Hayden thermal sensor OR nothing, and very noisy.
I did not like the noise from the fan at full blast.

I did not like the engine temperature CHANGING between
medium and low temperature on the gage, due to the way Hayden's temp sensor is set up.
Running the fan full on has got to reduce the fans lifespan.
Engine temperature fluxuation can NOT be good for the HG. :confused:

I just put a Delta Current Control in and it WORKS as claimed.
and is surprisingly quiet. :D

Just set the radiator temp per http://www.dccontrol.com/fk35.htm

Now when I turned off the engine the fan is still turning but very quiet.
(vs full blast). I like the post radiator cooling

However, I wedged the temp probe sensor between the fins and the housing,
as I could not get the probe between the fins.

I think I may put a Delta current control on my tranny cooler fan.

.
 
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that great! just one more question. if i disconnect wire 14. is it possible to have the high speed come on if i were to go 90 mph on the highway

I'm not aware of any reason why the high speed fan would come one if you were doing 90 mph....as far as I know the High speed only comes on when the engine coolant reaches the temp the EEC is programed to turn it on.

David
 
oh i was under the impression that the high speed came on when doing high speed driving. so let me rephrase the question. would the high speed come on @ the set eec temp.
 
The SC fan is a two speed fan that does this through having two seperate sets of windings in the motor.

If you rig it so the low speed fan is on all the time, you don't want the high speed fan to come on. Yes, if the coolant gets to something like 227 degrees the EEC will trigger the high speed fan.

By design, the fan motor is not able to withstand having both windings energized. The current draw will be too high and generate enough heat to melt things. Thus the factory setup is that the low speed fan cuts out when the high speed starts. But by cutting the #14 wire you remove low speed fan control from the EEC.

Dave's drawing that he posted is for people that want to have more control over the fans yet allow the EEC to do what it wants to within reason.
 
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