Today i do my weekly crank it up and let it run a while on my 1083 and for the first time in 2 yrs as soon as it started the trans fans come on blowing like hell and ive never herd them come on at all in 2 yrs . Any thoughts
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Anyone know what triggers transmission cooler fans to come on
- Thread starter chucky
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islandguydon
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Common sense dictates a stuck thermo micro switch, the high temp on is stuck. tap on it, if you can get it in your hands soak in vinegar. That's my humble opinion.
Ronmar
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Actually just looked this up during a discussion I was having yesterday
On an A0, The aux trans fans are controlled by relay K15. Relay K15 is wired in parallel with the engine cooling fan air solenoid so should come on when the main fan clutch engages whenever the coolant temp exceeds 200F.
if your air tanks are full and main switch on(engine off) you should be able to rotate your engine fan easily by hand. Also when you turn the switch off, you should hear the fan solenoid on the passenger side de-energize and release the fan freewheel air. If you cannot Rotate the fan with switch on or dont hear the fan solenoid, you may be missing power from CB22. or the temp sw on the upper rad pipe Or some circuit wiring may be open.
if the fan works as described, maybe K15 is bad as it uses the de-energized contacts to power the aux cooler...
what happens when you switch on the Fan/fording switch?
On an A0, The aux trans fans are controlled by relay K15. Relay K15 is wired in parallel with the engine cooling fan air solenoid so should come on when the main fan clutch engages whenever the coolant temp exceeds 200F.if your air tanks are full and main switch on(engine off) you should be able to rotate your engine fan easily by hand. Also when you turn the switch off, you should hear the fan solenoid on the passenger side de-energize and release the fan freewheel air. If you cannot Rotate the fan with switch on or dont hear the fan solenoid, you may be missing power from CB22. or the temp sw on the upper rad pipe Or some circuit wiring may be open.
if the fan works as described, maybe K15 is bad as it uses the de-energized contacts to power the aux cooler...
what happens when you switch on the Fan/fording switch?
I will look at k15 i was just amazed the fans came on its the first time in 2 yrs its ever happend and the truck was cold when i started it and the fans came on soon as it started and stayed on till i cut the truck offActually just looked this up during a discussion I was having yesterday
if your air tanks are full and main switch on(engine off) you should be able to rotate your engine fan easily by hand. Also when you turn the switch off, you should hear the fan solenoid on the passenger side de-energize and release the fan freewheel air. If you cannot Rotate the fan with switch on or dont hear the fan solenoid, you may be missing power from CB22. or the temp sw on the upper rad pipe Or some circuit wiring may be open.
if the fan works as described, maybe K15 is bad as it uses the de-energized contacts to power the aux cooler...
what happens when you switch on the Fan/fording switch?
Finally got back to truck as soon as i turned key on and fliped master switch on trans fans start blowing instead of starting the truck i got in fuse/relay panel and as soon as i wiggled k-15 the fan stop then come on then stop so i pull the relay and get to looking closely its a 12 v relay and the relay map on the panel calls for 24v so i put 1 in and now no fan blowing and i can turn main eng fan switch on with switch off the fan blade locks direct is that correct ?Actually just looked this up during a discussion I was having yesterday
if your air tanks are full and main switch on(engine off) you should be able to rotate your engine fan easily by hand. Also when you turn the switch off, you should hear the fan solenoid on the passenger side de-energize and release the fan freewheel air. If you cannot Rotate the fan with switch on or dont hear the fan solenoid, you may be missing power from CB22. or the temp sw on the upper rad pipe Or some circuit wiring may be open.
if the fan works as described, maybe K15 is bad as it uses the de-energized contacts to power the aux cooler...
what happens when you switch on the Fan/fording switch?
Ronmar
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My truck had a 12v relay there as well when I got it. I dont have an aux cooler, I noticed it because it was warm... K15 also has to be a 5 pin relay Or your cooler fans will never come on...
under normal conditions when you turn on the main sw, K15 should energize. The fan solenoid air valve(Under passenger dash) should also energize. If there is air in the tanks, That Valve sends air to the fan releasing it’s clutch so you can turn the fan blades by hand. When you turn off the main switch the solenoid valve releases the air from the fan and you can hear it go woosh on the passenger side. No woosh when you switch off the main switch then you either dont have air or that solenoid didn’t energize...
The fan/fording switch doesn’t do anything when the engine is below 200F its purpose is to disengage the fan clutch(Or keep it from engaging)... Below 200F the fan clutch is already disengaged...
I think i put a 4 pin 24 v back in when i looked i didnt see a bottom wire for anything to plug into in k 15 unless it has gotten pushed out of the relay receptical i will look tomorrow and replace with 5 pin 24v thanks for the knowledge there must be some kind of gremlin for them to just start coming on after 2 years of nothing
Ronmar
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Not a gremlin, just that 12v relay coil started to fail after years With 24v applied To it.
4 pin relays have top, bottom left and right. The 5th pin is at the middle of the cross. if you pull K12 to the left of K15 you will see top, bottom left and right connectors On the panel and no center connector. Left and right on the relay are the coil. top is the common connector(Pin30), bottom(Pin87)is where the top connector Completes a circuit to when energized, the center connecter(87A) is where the top connector connects to when the relay is de-energized.
The K15 socket doesn’t have a bottom connection because K15 doesn’t power anything when energized, it only powers the trans cooler fans when it is de-energized.
really silly the way they did this. 5 pin relays fit in all sockets so can be used everywhere, they should have only specced 5 pin relays in 12 and 24v instead of 4 different relay part numbers Spread across various locations...
4 pin relays have top, bottom left and right. The 5th pin is at the middle of the cross. if you pull K12 to the left of K15 you will see top, bottom left and right connectors On the panel and no center connector. Left and right on the relay are the coil. top is the common connector(Pin30), bottom(Pin87)is where the top connector Completes a circuit to when energized, the center connecter(87A) is where the top connector connects to when the relay is de-energized.
The K15 socket doesn’t have a bottom connection because K15 doesn’t power anything when energized, it only powers the trans cooler fans when it is de-energized.
really silly the way they did this. 5 pin relays fit in all sockets so can be used everywhere, they should have only specced 5 pin relays in 12 and 24v instead of 4 different relay part numbers Spread across various locations...
That explains the missing connector for sure i still cant get rapped around 24v vs 12 relay the 12 carrys more amperage/ voltage you would think a 12v in a 24v spot would last forever ! Electrical is by far my weak link on these trucks but im slowly learning one mishap at a time Thank you for your help.
Ronmar
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The 12/24 is the coil rating. If you take an ohm meter and measure the two coils they will have different resistances. basically the two different coils are wound differently to make the same amount of magnetic force From different voltages. So 12v coils with 24v applied Have way to much energy and turn the excess energy into heat. 24v coils with 12v applied have barely enough energy to pull in the contacts and don't always hold the contacts reliably.
in the case of these type relays, the contacts are not all that different between the two types...
coachgeo
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for clarity..... your saying the relays listed as 12/24 have two coils and something inside automatically detect which Voltage and thusly sends the power to appropriate coil?
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No hes saying how the 12 and the 24 are wound diferantly and why if the wrong one used will not function corectly so be sure what relay and how many pins is required is the way i took it.
Ronmar
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Chucky has it right. I was refering to the Coil ratings Of individual relays, either 12 or 24. There are no dual rated ones that I am aware of. 12v and 24v relays are basically the same, they simply have different coils... In fact if you were really hard up for parts, you could probably disassemble a relay and swap in the coil or contractor assembly from another relay... but it is probably just as easy to jumper across the relay socket until y0u can get the correct part...