North American Turbocoupe Organization



driver side fan not coming on
Jmantooth Offline
Junior Member
#1
ok, so the passenger fan comes on when the AC is on and when the temp gauge gets hot.  The driver side fan does not come on at all.  I think the temp sensor is working as it should due to the passenger fan coming on when the car gets hot and the AC is off.  Should I be looking at the IRCM fan relay as the reason for the driverside fan not coming on?
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88 Turbo Coupe Offline
Member
#2
Did you run 12 volts directly to the motor, to check the fan itself?
88 TC
5 Speed
Custom 2.75" stainless steel mandrel exhaust, cross drilled rotors (KVR), 245 50 ZR Eagle F1 GS-D3 (front & rear). This tire works amazing with the PRC. Wet or Dry! Lowered 1.75 inches
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Jeff K Offline
Administrator
#3
^^^^ Exactly

Jump the fan directly to the battery to see if it runs. All DC brush motors are considered wear items and will eventually fail. New motors are available for around $30 or so and easy to replace.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Jmantooth Offline
Junior Member
#4
Yes, I did run 12v to the fan directly. and It does work. I replaced the IRCM and the driver fan still will not come on. the Passenger fan comes on when it gets hot and when the AC is on. It will cycle on and off with the AC off and stay on so long as the AC is on.
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JT Offline
Posting Freak
#5
The driver's side fan is an auxiliary fan. It will only turn on if the engine temperature exceeds somewhere around 220F and/or if the A/C head pressure exceeds somewhere around 310PSI.

You can test the driver's side fan by jumping the high-side pressure switch connector while the key is on to simulate high a/c head pressure.
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88 Turbo Coupe Offline
Member
#6
You can also disconnect the passenger fan and watch the temp gauge to see if the aux fan (driver side) turns on. Just don't let the motor over heat.

I believe that fan was designed for extremely hot days with the motor under heavy load. I rarely have seen mine turn on with the temp gauge going in the upper top section of the gauge. So much so I wired in a relay so it would turn on when the main fan (passenger side) turned on. I did this for extra cooling.

It worked well and the motor actually ran too cool (something you do not want). So I installed a switch so I could turn it on when the car started running a bit hotter. The running hot issue was resolved with a new temp switch, then a new thermostat and finally what worked 100% was a new thermostat housing with new thermostat.
88 TC
5 Speed
Custom 2.75" stainless steel mandrel exhaust, cross drilled rotors (KVR), 245 50 ZR Eagle F1 GS-D3 (front & rear). This tire works amazing with the PRC. Wet or Dry! Lowered 1.75 inches
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Jeff K Offline
Administrator
#7
Check your ECT resistance or output voltage vs temperature to see if it is within spec.

There is a recent post by Rob H where this was discussed in detail.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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JT Offline
Posting Freak
#8
What is being used to determine the engine is "hot"? The factory gauges are not precise.

Unless the engine is running abnormally hot, the auxiliary-driver's side fan normally doesn't run for engine temperatures. It's possible it's not working, given the statement it doesn't turn on with the A/C on, but the A/C has to be working hard enough to trigger the auxiliary fan.

Edit: It's possible the circuit is not working and the engine is hot. So if you think there's a problem, it is good to investigate as we can't check engine temperature from here. But just saying that in the last 10+ years, my auxiliary fan has never turned on. It does work. The engine simply doesn't get abnormally hot nor does the A/C request it due to a/c head pressure and that's sort of typical. You won't often see the auxiliary fan operate under normal conditions.
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Jeff K Offline
Administrator
#9
^^^ Same here...... my aux fan (driver side) has never run during the 20 years and 110K miles I have owned my TC, and that includes 2 trips from Wisconsin to Dallas in August with ambient temps over 100 deg F and AC on running an 80+% duty cycle to cool the interior down. I know it works, as it briefly runs during the KOEO self test as expected, and I have a switch and indicator light on the dash (switch in parallel with the high side AC pressure switch) just in case I ever needed to run it if my main fan (pass side) ever fails.

To the OP..... if you run the KOEO self test, both fans should briefly run. If either doesnt run when commanded on a code will be set. PCM looks for the voltage drop in the electrical system due to the high inrush current as the fan motor spools up. Also, the main fan (pass side) should run continuously during the KOER self test. Might want to have a close look at the IRCM electrical connector looking for damaged / corroded / pushed out pins.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Jmantooth Offline
Junior Member
#10
Ill try a KOEO test and report back.
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