fj40 carb cooling fan...do you run yours? (4 Viewers)

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I can get the measurements, maybe tonight. I just had the air cleaner off Saturday, maybe I can get the measurements without removing it. Quit bumping Eddy...........
 
If I can get my stubby fat fingers in there.

Monday bump for Eddy's bump.
 
Fast Eddy said:
I have a full schematic of the controller. The operation of the earlier type is different than the later one in my '78 and the earlier circuit is much simpler.
Click to expand...

Care to share that full schematic? ;) Always interested in something I don't have!
 
I'd share it if I knew it was correct. There is one diode, one cap and one transistor I need to id and I need to verify the pinout and orientation of the other transistors. There are four total.

Once I get the correct sensor, if it works, it will be easy to verify the other components. I'm going to bite the bullet and buy one from $OR.
 
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So Eddy, I checked the resistance last night as soon as I got home with the engine warm. No resistance. Checked the engine with my temp gun and it was 130 - 150 degrees. Let it cool down and .... no resistance. Gee, I'm guessing my sensor is toast?
 
Fast Eddy said:
I'd share it if I knew it was correct. There is one diode, one cap and one transistor I need to id and I need to verify the pinout and orientation of the other transistors. There are four total.

Once I get the correct sensor, if it works, it will be easy to verify the other components. I'm going to bite the bullet and buy one from $OR.
Click to expand...

I don't have a later Carb Fan Module or I would help you verify it. I may use the solid state timer from Waytek to power my fan. I bought one last week and have been playing with it.
 
Mine doesn't seem to be working. I could send it to someone to play with if they'd like.
 
myquestoyota said:
So Eddy, I checked the resistance last night as soon as I got home with the engine warm. No resistance. Checked the engine with my temp gun and it was 130 - 150 degrees. Let it cool down and .... no resistance. Gee, I'm guessing my sensor is toast?
Click to expand...

After reading through the book pages that were posted about this thermosensor I came to the conclusion that your sensor is either bad, or your meter isn't working. However, you also did not get it hot enough to turn on the fan according to the manual. All the following assumes the thermosensor is actually a NTC (Negative Temperature Coefficient ) thermister ie as temp goes up resistance goes down

The thermistor reading is supposed to be 2.0 K (2000 ) to 3.8 K (3800) ohms when it's temp is 194 F to 230 F degrees . You have to heat it up to at least 194-230 degrees before it will read the 2 K to 3.8K . So put it in cooking oil and set it on the stove with a candy thermometer and get it above 194 degrees and see what it reads.

Since the test in the Toyota manual shows that you ground the thermosensor input to test the fan , logic (and assuming it's a NTC thermister) would indicate that the resistance of the thermosensor COLD would be very high. Probably in the 100K ohm range at 75 F degrees.

Now I know next to nothing about thermomisters built in the 70's, but if they act like ones built today, you should have had readings like this: At 75 F 100K ohms, at 150 degrees your reading should have been around 18,000 ohms. If your meter can read those values and it did not, your sensor is probably bad...

If we can find the range of values a working Toyota thermosensor has, I can locate a replacement that hopefully won't cost $100.00...
 
I am going to take mine off and play with it. Would cooking oil work better than water? I am pretty sure my meter is fine but interested in some input for testing it. It was kind of awkward testing it under the hood and I realize I was not near hot enough to have it turn the fan on. When I reinstall I may find a hotter place for it, probably by just bending the mount to get the sensor closer to the manifold.
 
Coolerman said:
The thermistor reading is supposed to be 2.0 K (2000 ) to 3.8 K (3800) ohms when it's temp is 194 F to 230 F degrees . You have to heat it up to at least 194-230 degrees before it will read the 2 K to 3.8K . So put it in cooking oil and set it on the stove with a candy thermometer and get it above 194 degrees and see what it reads.

Since the test in the Toyota manual shows that you ground the thermosensor input to test the fan , logic (and assuming it's a NTC thermister) would indicate that the resistance of the thermosensor COLD would be very high. Probably in the 100K ohm range at 75 F degrees.
Click to expand...

Great info. Where'd you read that? I mean, which manual? I've been looking without any luck.

Coolerman said:
If we can find the range of values a working Toyota thermosensor has, I can locate a replacement that hopefully won't cost $100.00...
Click to expand...

I've got one on the way from SOR. They're "only" $47 with tax and shipping and hopefully a bracket. I'm not above a zip tie though.

We will have a nice graph by Saturday. :)

myquestoyota said:
I am going to take mine off and play with it. Would cooking oil work better than water? I am pretty sure my meter is fine but interested in some input for testing it. It was kind of awkward testing it under the hood and I realize I was not near hot enough to have it turn the fan on. When I reinstall I may find a hotter place for it, probably by just bending the mount to get the sensor closer to the manifold.
Click to expand...

Water will be violently bubbly and steamy at the temps you need. Oil will be hot, but it will just sit there.

Once we have data from a working sensor, you will be able to adjust the "on" temperature by adding a resistor to the circuit board. As time permits I'll probably try to make a full copy of the timer/relay so the "on" temp and the duration can be adjusted.
 
Okay, so submerging my sensor in hot oil won't damage it? I mean if I do get some resistance when it is cold. I still need to peek at my circuit board also.
 
For sure, I have one I use when deep frying...everything!:beer:
 
myquestoyota said:
Okay, so submerging my sensor in hot oil won't damage it? I mean if I do get some resistance when it is cold. I still need to peek at my circuit board also.
Click to expand...

In oil is the way the manual says to test it. You will never get water to go over 212 degrees. ;)
 
I didn't have a thermometer handy, but the earlier sensor seems to be a switch. No connection when at room temperature and very low or no resistance when heated and it finally pops open.

Unfortunately this means that my relay/timer is bad. :(
 
Now I am scared to hook up all my stuff..................
 
Fast Eddy said:
I like the idea of the fan moving the hot air around and hopefully out the vents.
Click to expand...
Could be way off-base here, but , the fan should blow DOWN--away from the manifolds so the temp change does not impact the metal integrity- thinking the fan direction should be pointing at about the angle of the exhaust manifold gasket(this is assuming the fan is located in the front left of the engine compartment)--If it's blowing(pointing) out the hood vents, it would be reduced cooling, and potentially blowing straight on the heated metal of the manifolds(bad)
 
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