aquillen
09-11-2019, 10:13 AM
This probably represents high end of power draw for a Subaru fan setup, but the 4 bangers may well use just as much for their fans. These are a pair of used 2002 Outback LL Bean donor fans which I completely rebuilt, installing new bearings and recut/trued the commutators, so I believe they are good representative motors for this test. I'm posting this because another member asked what my max fan current draw was, so why not list the info I gathered just in case someone else could use this.
Both fan motors are rated 120 Watts, so 10 amperes each is the rating. But the fan blades, atmospheric pressure, etc., determine actual power draw at max operation, and from testing at 12 volts, the draw is somewhere below 10 amperes for each motor. At a full 14.5 volts with running engine and a charged battery it is quite likely one or both would pull up there at 10 amperes but I didn't test that.
There are two fans - main fan and sub fan, the two fans are controlled together by the ECU - both run at the same speed. The main fan has 7 blades and each blade is a bit more narrow than the wider blades on the sub fan, of which there are 5.
Although they can be wired for up to 4 different speeds, the service documents shows 3 speeds are used. Speeds are selected by the ECU. One ground wire is always connected. Looking at just the main fan, a second ground is connected when the ECU energizes relay F31 which increases the speed capability depending on the ECU control of fan relays #1 and #2. Fan relay 1 enables partial speed, Fan relay 2 enables additional speed. (NOTE: The test procedure in the manual uses the wiring in a different configuration to test the motors, but the ECU determines fan speed via the 2nd ground relay and the two Fan relays.)
Voltage measured with Fluke87, current with Wavetek CT233 clamp on meter.
Battery voltages were applied at 2 inches from the fan motor's local connector plugs (chopped off connector pigtails not yet wired to car circuits). Since mid speed is determined by the ECU and I don't happen to know whether it does this by using both ground -or- both 12V leads, I only list the low and high speed current tests here. In any event mid speed will be somewhere between the low and high current draws.
Refer to the drawing below.
(5 amperes at Main fan slow speed) - F17 pin numbers:
4 - Gnd
1 - 12.3V
(7.4 amperes at Main fan high speed) - F17 pin numbers:
4 - Gnd
3 - Gnd
1 - 12.0V
2 - 12.0V
(6. amperes at Sub fan slow speed) - F16 pin numbers:
4 - Gnd
1 - 12.2V
(9.0 amperes at Sub fan high speed) - F16 pin numbers:
4 - Gnd
3 - Gnd
1 - 11.9V
2 - 11.9V
This is my project's schematic, adapted from the 2002 Outback factory drawings:
https://res.cloudinary.com/aq007/image/upload/v1568211574/818C-3.0_W9_FANS_k1okpr.jpg
Both fan motors are rated 120 Watts, so 10 amperes each is the rating. But the fan blades, atmospheric pressure, etc., determine actual power draw at max operation, and from testing at 12 volts, the draw is somewhere below 10 amperes for each motor. At a full 14.5 volts with running engine and a charged battery it is quite likely one or both would pull up there at 10 amperes but I didn't test that.
There are two fans - main fan and sub fan, the two fans are controlled together by the ECU - both run at the same speed. The main fan has 7 blades and each blade is a bit more narrow than the wider blades on the sub fan, of which there are 5.
Although they can be wired for up to 4 different speeds, the service documents shows 3 speeds are used. Speeds are selected by the ECU. One ground wire is always connected. Looking at just the main fan, a second ground is connected when the ECU energizes relay F31 which increases the speed capability depending on the ECU control of fan relays #1 and #2. Fan relay 1 enables partial speed, Fan relay 2 enables additional speed. (NOTE: The test procedure in the manual uses the wiring in a different configuration to test the motors, but the ECU determines fan speed via the 2nd ground relay and the two Fan relays.)
Voltage measured with Fluke87, current with Wavetek CT233 clamp on meter.
Battery voltages were applied at 2 inches from the fan motor's local connector plugs (chopped off connector pigtails not yet wired to car circuits). Since mid speed is determined by the ECU and I don't happen to know whether it does this by using both ground -or- both 12V leads, I only list the low and high speed current tests here. In any event mid speed will be somewhere between the low and high current draws.
Refer to the drawing below.
(5 amperes at Main fan slow speed) - F17 pin numbers:
4 - Gnd
1 - 12.3V
(7.4 amperes at Main fan high speed) - F17 pin numbers:
4 - Gnd
3 - Gnd
1 - 12.0V
2 - 12.0V
(6. amperes at Sub fan slow speed) - F16 pin numbers:
4 - Gnd
1 - 12.2V
(9.0 amperes at Sub fan high speed) - F16 pin numbers:
4 - Gnd
3 - Gnd
1 - 11.9V
2 - 11.9V
This is my project's schematic, adapted from the 2002 Outback factory drawings:
https://res.cloudinary.com/aq007/image/upload/v1568211574/818C-3.0_W9_FANS_k1okpr.jpg