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Hello,
so I recently replaced my heater hose and some coolant hoses along with my radiator. Everything seems to be fine while driving. Doesn't run hot, and stays steady temp.
But when I turn my car off, my fans stay on, draining my battery. I've heard a temp sensor could cause to run hot, could it cause to run my fans? Or maybe something elcteical? Help!
1997 accord ex
2.2.
The fans should come on after the engine is thoroughly warmed up to prevent overheating. You should verify that with the engine warmed up and running, that the fans do come on automatically when they are supposed to.
Also see if the fans turn on right away on a cold engine when you first start it, (when they aren't supposed to) this could help troubleshooting by telling you if they are permanently stuck in the closed circuit, running mode of operation.
Try seeing if the fans shut on and off with the vehicle warmed up and running, they should cycle. Also check to see which of the two fans is/are operating, whether its both or just one (condenser fan & radiator fan).
Three things your going to want to look at are, the radiator fan switch, the radiator fan relay and the condenser fan relay. There is also a very rare chance, but not impossible, that there is a short to power between the wires that feed the fans and another 12V wire.
If you have access to a multimeter you can test these three components by checking for voltage and continuity at various places.
The radiator fan switch is located on the outside of the thermostat cover. It for instance can be tested by placing it in hot water and testing for continuity.
The radiator fan switch turns "ON" or closes the circuit between 198-208°F and is "OFF" between 4-13°F
The relays are a little more tricky, you'd need wiring diagrams, for the cost of the relays, I'd just buy replacements and see if it helps.
It can really be any of these things but my guess would be a sticking relay, though unlikely that both fan relays would be faulty, again, let us know the specifics of what fans are turning on and when.
Thanks, I can obviously unplug my relay and they shut off, but back in again when i plug it back in.
they don't start right away, but stay on after they turn on.
It's also not throwing a code.
Originally Posted by Accordian47
The fans should come on after the engine is thoroughly warmed up to prevent overheating. You should verify that with the engine warmed up and running, that the fans do come on automatically when they are supposed to.
Also see if the fans turn on right away on a cold engine when you first start it, (when they aren't supposed to) this could help troubleshooting by telling you if they are permanently stuck in the closed circuit, running mode of operation.
Try seeing if the fans shut on and off with the vehicle warmed up and running, they should cycle. Also check to see which of the two fans is/are operating, whether its both or just one (condenser fan & radiator fan).
Three things your going to want to look at are, the radiator fan switch, the radiator fan relay and the condenser fan relay. There is also a very rare chance, but not impossible, that there is a short to power between the wires that feed the fans and another 12V wire.
If you have access to a multimeter you can test these three components by checking for voltage and continuity at various places.
The radiator fan switch is located on the outside of the thermostat cover. It for instance can be tested by placing it in hot water and testing for continuity.
The radiator fan switch turns "ON" or closes the circuit between 198-208°F and is "OFF" between 4-13°F
The relays are a little more tricky, you'd need wiring diagrams, for the cost of the relays, I'd just buy replacements and see if it helps.
It can really be any of these things but my guess would be a sticking relay, though unlikely that both fan relays would be faulty, again, let us know the specifics of what fans are turning on and when.
The fan relays, radiator fan switch and the radiator fan control module are not a part of the system that throws a code, so you won't have a code for those things.
Have you tried testing the radiator fan switch? It could be faulty, causing it to be "open" or "off" when you first start the car like it should be but when warmed up and "on", sticking in the "on" position causing the fans to stay constantly running even if temperature drops below threshold.
Where is the radiator fan switch? I'm looking. Not sure how to test it.
Duh!! I'm dumb. How do I test it haha
Originally Posted by Accordian47
The fan relays, radiator fan switch and the radiator fan control module are not a part of the system that throws a code, so you won't have a code for those things.
Have you tried testing the radiator fan switch? It could be faulty, causing it to be "open" or "off" when you first start the car like it should be but when warmed up and "on", sticking in the "on" position causing the fans to stay constantly running even if temperature drops below threshold.
Remove the radiator fan switch from the thermostat housing. See below:
2. Suspend switch in a container of water so that the tip of the switch is submerged
3. Insert a thermometer into the water (partially) and heat the water in accordance with the following temperature values:
4. Use a multi-meter on the "Continuity Test" setting to see if there is an electrical connection being made by the switch between the two pins of its electrical connector
Basically when its hot or between 198 and 208, the two pins will be connected and when it is 4-13 degrees lower than the 198-208 range it will be "OFF" and the two pins won't be electrically connected.
*NOTE: I got the temperature values from ALLDATA for my '01 Prelude, not 100% sure if the temps will be the same for your 97 Accord.
The '01 Prelude Radiator Fan Switch Part # is: 37773-P13-004 and for your '97 Accord EX its: 37760-P00-003 so they aren't the exact same switch, you may want to confirm your testing for the right temps, I'll see what I can find.
1. On the thermostat housing (lower radiator hose) is fan thermo-switch A, which turns the radiator fan on at around 199 degrees F when the car is running.
A faulty fan switch A (on the thermostat housing) by itself would not cause the fans to keep running when the car was turned off.
2. The fan switch on the upper radiator hose housing is thermo-switch B, which turns the radiator fan on when the car is off, if the temperature is around 223 degrees F. The Radiator Fan Control Module also acts as a timer and will turned the radiator fan off after a set amount of time.
A faulty fan switch B by itself would not cause the fans to keep running continuously when the car turned off.
3. There is a condenser fan relay and radiator fan relay to run each of the respective two fans. One faulty relay would not cause both fans to run after the car was turned off.
4. The Radiator Fan Control Module controls the power (+) to both the condenser fan relay coil and the radiator fan relay coil. The fan switches control the ground (-) to both the condenser fan relay coil and the radiator fan relay coil.
5. How the mechanical relay works is (a) when relay coil is energized by power and ground then (b) the relay contacts close (think of it like a draw bridge) to power allowed through to the fan.
2. The fan switch on the upper radiator hose housing is thermo-switch B, which turns the radiator fan on when the car is off, if the temperature is around 223 degrees F. The Radiator Fan Control Module also acts as a timer and will turned the radiator fan off after a set amount of time.
A faulty fan switch B by itself would not cause the fans to keep running continuously when the car turned off.
.
It seems then it would most likely be the Radiator Fan Control Module since it acts as a timer. After the car is turned off it is designed to still power the fans momentarily? I've never heard my '99 Accord do it but occasionally I'll hear fans running on a parked vehicle that's turned off.
It seems then it would most likely be the Radiator Fan Control Module since it acts as a timer. After the car is turned off it is designed to still power the fans momentarily? I've never heard my '99 Accord do it but occasionally I'll hear fans running on a parked vehicle that's turned off.
Yes, the earlier model Accords (90 - 93 4th gen, and 94 - 97 5th gen) had a radiator fan control module which also acts as a timer after the car is turned off, if the coolant temperature at the fan switch B (on housing where upper hose connects) is above 223 degrees F on 5th gen Accords. The fan switch (Switch A) on the thermostat housing is not part of the circuit designed to run the fan when the car is turned off; only on.
This is an illustration of the fan circuit on a 97 Accord.
A faulty relay (where the contact side was stuck) can run the one fan if the car was off. The two fan relays are positioned right next to each other on a 5th gen Accord; so, it is easy to swap them to check.
Yes, the earlier model Accords (90 - 93 4th gen, and 94 - 97 5th gen) had a radiator fan control module which also acts as a timer after the car is turned off....
Your 99' Accord does not have that module.
Interesting information - thanks. I always thought it was odd hearing fans running in an unoccupied non-engine running vehicle.
Originally Posted by tech8
It may be a faulty radiator fan control module, which is located behind the glove box.
That does seem most likely. As also stated it's not likely the radiator fan switch as the final connection to the fan(s) is the radiator fan control module. Don't know if the fans are driven directly by a transistor, or more likely a transistor firing a relay - but something that draws more current than usual can cause a relay to stick on mechanically via the contacts. I've seen where physically striking the relay will cause it to release (assuming no voltage to the coil). Worn contacts can cause that too. I think the Op said removing the relay will of course cause the fans to turn off, but when re-inserting them (or it) the fans would not immediately turn on, but would stay on continuously after they turned on.
This is an illustration of the fan circuit on a 97 Accord.
A faulty relay (where the contact side was stuck) can run the one fan if the car was off. The two fan relays are positioned right next to each other on a 5th gen Accord; so, it is easy to swap them to check.
Your post came up while I was posting mine! Answers my question (fans are relay driven) and it sounds like we're on the same page with the relay sticking
In this link, they refer to the radiator fan control module as a fan timer on a 4th gen Accord. On a 5th gen, the module is located behind the glove box, shown in my first post of this thread.
Interesting information - thanks. I always thought it was odd hearing fans running in an unoccupied non-engine running vehicle.
That does seem most likely. As also stated it's not likely the radiator fan switch as the final connection to the fan(s) is the radiator fan control module. Don't know if the fans are driven directly by a transistor, or more likely a transistor firing a relay - but something that draws more current than usual can cause a relay to stick on mechanically via the contacts. I've seen where physically striking the relay will cause it to release (assuming no voltage to the coil). Worn contacts can cause that too. I think the Op said removing the relay will of course cause the fans to turn off, but when re-inserting them (or it) the fans would not immediately turn on, but would stay on continuously after they turned on.
Originally Posted by Stelcom66
Your post came up while I was posting mine! Answers my question (fans are relay driven) and it sounds like we're on the same page with the relay sticking
From reading this I thought the only years that had a fan control module were the 4th gens and the 5th gens. Original poster's car is a 97, so 6th gen.
From reading this I thought the only years that had a fan control module were the 4th gens and the 5th gens. Original poster's car is a 97, so 6th gen.
Fans won't shut off?
