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10-18-2016, 10:41 AM | #1 |
Drives: Yaris Verso 1.3 2000 automatic Join Date: Nov 2015
Location: Poland
Posts: 33
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Radiator fan doesn't start when the engine gets hot
Hi,
Here are the symptoms: - red temperature warning light starts flashing after some time, usually in city traffic - when the above occurs the radiator fan does not spin - the fan spins when I engage AC (even when the engine is cold) I exchanged FAN N.01 relay switch with HORN relay switch to see if the horn works and it does. When I remove the FAN N.01 relay and connect two pins with a wire as marked in the picture below, the fan starts spinning. relay.png |
10-18-2016, 01:06 PM | #2 |
Drives: Sedan 07 Join Date: Oct 2012
Location: Asia
Posts: 478
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Based on your observations the trigger of the relay (in the wiring) is faulty, but assuming the AC uses the same relay, then more likely the culprit is the thermoswitch than the thermostat.
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10-18-2016, 02:16 PM | #3 |
Drives: Yaris Verso 1.3 2000 automatic Join Date: Nov 2015
Location: Poland
Posts: 33
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Thermoswitch is normally open?
Is it connected directly to FAN N.01 or FAN N.02 relay? |
10-18-2016, 07:35 PM | #4 |
ULTIMATE
Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
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The fan No 1 relay coil is controlled by the AC ECU.
It in turn feeds as one of the triggers for the Fan No 2 relay (and gives the AC ECU the ability to turn the fan on when the engine is not hot). The Fan No 2 relay also has two other triggers in parallel with the AC ECU (so any of the three can turn it on): ECM output CF (cooling fan) and Water temp switch. The fact that bypassing No 1 makes it turn on just tells you that either the ECM output or the water temp switch is the issue.
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10-19-2016, 01:22 AM | #5 | |
Drives: Yaris Verso 1.3 2000 automatic Join Date: Nov 2015
Location: Poland
Posts: 33
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Quote:
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10-19-2016, 12:17 PM | #6 |
Drives: Yaris Verso 1.3 2000 automatic Join Date: Nov 2015
Location: Poland
Posts: 33
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Today I managed to get the fan running when I shorted the wires from Water Temp Switch plug. So it seems the switch is not working. I'm replacing it tomorrow.
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10-20-2016, 01:27 AM | #7 |
Drives: 2009 5-door, 5-speed Join Date: Sep 2011
Location: White Rock BC
Posts: 687
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If you haven't done so, you may want to check your coolant level. Those switches only work when submerged.
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