Fan Motors - a Chilling exposé

General discussion about our beloved Tercel 4WD cars
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3A-C Power
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Post by 3A-C Power » Mon Apr 26, 2004 1:26 pm

Though they used basically the same rad for all AL2x series Tercels, there were 3 different fan motors in the series for North American vehicles, each with a different power level. To summarize from weakest to strongest, in working amperage range:

1: 4.2 - 5.4
2: 5.8 - 7.4
3: 8.8 - 10.8

The strongest one is two times as powerful as the weakest. In a DC motor, the torque is directly proportonal to the current, so twice the amperage gives you twice the torque. I have yet to determine whether they put the torque to use with a more agressive fan, or whether the stronger motors simply ran faster with the same fan.

They were specified according to region, body style, transmission, and presence of air conditioning in the following manner:

..........................USA....Canada
Hatchback
....Manual..............1..........1
........with A/C........1..........2
....Automatic..........2..........1
........with A/C........2..........2
Wagon
....Manual..............2..........1
........with A/C........2..........2
....Automatic..........3..........2
........with A/C........3..........2

In summary, US model fan motors were specified such that being a wagon or having an automatic counted for one step up in power, with these two criterion being superimposed. Canada got the short end of the stick, the wagon counting for nothing except for the case of an automatic with no A/C. No Canadian models got the most powerful motor.

The weakness of the fan motor is multiplied when you increase the core thickness of the radiator, as more pressure is required to achieve the same airflow. Furthermore, more airflow is required to achieve the same cooling rate per unit surface area because the air is passing over more area of fins. So if you increase core thickness without increasing fan power, you have a radiator that requires more airflow than stock but is in fact getting less. Such can be observed in my wagon, in which the temp gauge climbs at idle, but drops rapidly in motion. The climb at idle is to be expected given the lack of airflow, while the rapid drop is a testament to the effect of the extra surface area and coolant flow when given an adequate airflow rate.

My car is a Canadain manual wagon that came without A/C. I added A/C without upgrading the fan motor. In addition, I tow trailers which greatly increases load. I have a fan motor from a US wagon with manual and A/C, so that's a step up from what I've got, but still it's just what I should have given the air conditioning. To provide adequate idle airflow for the triple-core rad, I will have to go beyond the factory specs.

GTSSportCoupe
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Post by GTSSportCoupe » Mon Apr 26, 2004 2:04 pm

Very interesting! That is great to know. My rad is leaking, so I'll have to upgrade it soon. I'll probably go with a large rad out of a Toyota. I've got a Camry fan sitting at home that I might try to adapt. I'm fairly sure it's flow capacity is beyond those of any of the tercels.
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Thereminator
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Post by Thereminator » Mon Apr 26, 2004 3:17 pm

Yeah 3A,I have Ac and when the Rad-Fan starts(wile idleing),the temp drops quickly and is on for about 30 sec.
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takza
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Post by takza » Mon Apr 26, 2004 7:10 pm

I've got an original thin OEM radiator and the only time the rad fan runs is when I'm offroad and idling along. The temp needle will rise just slightly before it runs.

I have heard it mentioned here and there, that the condensor fan can stop running and cause the AC to lose the freon due to overheating.

Wondering if anyone has tried oiling the bearings on the condensor fan????

Or the radiator fan???
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3A-C Power
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Post by 3A-C Power » Mon Apr 26, 2004 9:59 pm

My condenser fan stopped once when my ghetto fan relay installation failed. I had just wedged the wires into the A/C fan relay part of the fusebox and jammed the relay in there instead of installing terminals in the fusebox. My fusible plug blew and refrigerant leaked. I JB-welded the plug and added refrigerant, then it worked again. You can typically get at the motor parts for servicing, so oiling the condenser and rad fan bearing would be a really good idea for making them last. Or we could custom mount the highest amperage 12V DC motor we can find, and make the fan fit it.

Thereminator
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Post by Thereminator » Mon Apr 26, 2004 11:16 pm

Jon is the Amp-Rateing on the motor-unit where you can identify it. I might grab an extra a the yard.
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3A-C Power
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Post by 3A-C Power » Mon Apr 26, 2004 11:50 pm

I don't think so but you can know it given the car it's from, using my handy reference. It's from the Factory service manual actually.

Thereminator
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Post by Thereminator » Tue Apr 27, 2004 12:54 am

So if I find a 2X Wagon with auto and air(like the one they just crushed),It should have the "El Darado" of Fan-Motors? <_<
1984 SR5~Tercel 4wd-6.Spd<br><br>

Fingers
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Post by Fingers » Wed Apr 28, 2004 11:49 pm

Wow, I feel so special that I have the power of cooling on my side (a/c and auto), but my fan never turns off. I guess I could try to figure out why, but since it is summer I will probably not bother for a while. I was planning on swapping out my rad (I am amazed it don't leak, the top is kinda smashed in), but the fins are fine and it hasn't come close to getting hot, even delivering pizzas in 90 deg weather with a/c running full blast. And I am from the world of 'if it ain't broke, don't fix it...'. We'll see when it starts getting around 100+.
86 Tercel Wagon 4WD, 4AC, 3sp Auto. (2) 89 Corolla GT-S, 4AGE. 87 Corolla GT-S, 4AGE, SOLD! 68 Mustang Fastback, 351c.i.=>429c.i., 3 Speed Manual, 10 Year Plan. 66 Mustang GT350, 289c.i., 4 Speed Manual, SOLD!

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3A-C Power
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Post by 3A-C Power » Thu Apr 29, 2004 11:21 am

You probably have a bad connection between the temp sensor and the fan relay. If that connection is broken, the fan is on all the time. My temp sensor is screwed so I unplugged the wire and the fan runs all the time.

Thereminator
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Post by Thereminator » Thu Apr 29, 2004 5:11 pm

I looked at fan-units at the Yard today and even though the cooling system was diferent,the 80's Carolla seems to use the same fan-units.I also looked for an air-filter wingnut(for Carlos) but I think when people look at the carb,the wingnut is the first part to drop to the ground.Then a clean-up comes by with a rake and bye-bye wingnut. <_<
1984 SR5~Tercel 4wd-6.Spd<br><br>

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