Help with wiring radiator fan
Blink_32
04-17-2002, 07:45 AM
So, the wiring harness on the side to the fan got mangled. Before that though the fan would never come on no matter how hot the coolant temp got. So what I would like to do is hard wire a switch to the leads on the fan.
.
Its a 91 Escort Pony 1.9l
.
3 wires coming off of the fan. I found out which wires need to be hooked up to pos and neg for the fan to turn in the correct direction but I was using the battery terminals. That caused the wires to get excessively hot. Would grounding out to the chassis prevent too much current from flowing there-by preventing the wires from getting to hot? Or would I need to wire some other component inline to prevent this?
.
Its a 91 Escort Pony 1.9l
.
3 wires coming off of the fan. I found out which wires need to be hooked up to pos and neg for the fan to turn in the correct direction but I was using the battery terminals. That caused the wires to get excessively hot. Would grounding out to the chassis prevent too much current from flowing there-by preventing the wires from getting to hot? Or would I need to wire some other component inline to prevent this?
replicant_008
04-17-2002, 05:38 PM
Quick Tip:
Generally, the radiator fan is hooked to a fan relay. A relay is an electrical switch which is activated by another electrical circuit. In a radiator fan this activation circuit is usually by a temperature switch or from the PCM.
Caution:
A separate switch can be useful but is usually used as an override to some sort of temperature control. The use of override is used for instance when you want the fan to activate when the temperature switch has yet to activate (ie you turn it on before doing a drag switch run).
If no temperature control is active, the fan will not activate unless the operator notices a temperature variation. If this is overlooked then the radiator fan may not be activated and overheating may occur.
In your case, it doesn't sound like either the switch is missing or the PCM defective just the wiring to the fan. I'd suggest that you obtain a copy of a wiring diagram or a workshop manual (try the public library) and hook up the temperature control and relay. A workshop manual will tell you how to check the switch and the relay (usually with a voltmeter or test light).
A couple more tips, if the coolant is getting too hot, try checking the thermostat. And if the coolant gets too hot, one way to try to cool the coolant (this is strictly a limp home for short distance option) is to close all the air vents into the cabin, wind the windows down, turn off the a/c and turn the heater to full HOT. The heater gets its heat from the coolant so when you turn it on you effectively create an auxilary radiator. Only problem is that if it's a hot day, the last thing you want to do is roast in the car.
Detailed discussion:
The radiator cooling fan is only needed when engine temperature rises above a predetermined level -- or when there is an increased load placed on the cooling system (as when running your air conditioner). The rest of the time, running the fan would be a waste of electrical energy so it is turned off. Electrical energy being supplied by the battery or the alternator - producing charge from the alternator uses power and effectively uses more fuel so hence it's off when not needed. And it's also additional noise.
At highway speeds, there is usually enough airflow through the radiator that a fan isn't needed. So the fan usually only operates when the vehicle is sitting in traffic, driving at slower speeds or at high duty applications. These would include climbing steep terrain (particularly at altitude where the air is less dense and cools less), towing, very heavy loads or running the air-conditioning.
On older applications, the electric fan is controlled by a temperature switch located in the radiator or engine. When the temperature of the coolant exceeds the switch's rating (typically 195 to 235 degrees F ie 80 to 110 degrees C), the switch closes and energizes a relay that supplies voltage to run the fan. It works the opposite way from a oven temperature switch.
The fan then continues to run until the coolant temperature drops back below the opening point of the switch. Most electric fans are also wired to come on when the A/C is on. Many vehicles also have a separate fan for the A/C condenser (dual fan systems). One or both fans come on when the A/C is on.
In newer vehicles with computerized engine controls, fan operation is regulated by the engine control module (the computer that runs the fuel injection, ignition etc). Input from the coolant sensor, and in many cases the vehicle speed sensor too, is used to determine when the fan needs to be on.
CAUTION: Many electric fans are wired to come on anytime the engine is above a certain temperature, regardless of whether the engine is running or not. This means the fan may come on after the engine has been shut off. So keep your fingers away from the fan at all times unless the battery or fan motor wires have been disconnected.
CHECKING THE FAN
Four things can prevent a fan from coming on when it should: a bad temperature switch or coolant sensor (or problem in the switch or sensor wiring circuit); a bad fan relay; a wiring problem (blown fuse, loose or corroded connector, shorts, opens, etc.); or a failure of the fan motor itself. Only the latter would require replacing the fan motor.
One way to check the operation of the fan motor is to jump it directly to the battery. If it spins, the motor is good, and the problem is elsewhere in the wiring or control circuit. Another check is to test for voltage with a voltmeter or test light at the fan's wiring connector. There should be voltage when the engine is hot and when the A/C is on.
Generally, the radiator fan is hooked to a fan relay. A relay is an electrical switch which is activated by another electrical circuit. In a radiator fan this activation circuit is usually by a temperature switch or from the PCM.
Caution:
A separate switch can be useful but is usually used as an override to some sort of temperature control. The use of override is used for instance when you want the fan to activate when the temperature switch has yet to activate (ie you turn it on before doing a drag switch run).
If no temperature control is active, the fan will not activate unless the operator notices a temperature variation. If this is overlooked then the radiator fan may not be activated and overheating may occur.
In your case, it doesn't sound like either the switch is missing or the PCM defective just the wiring to the fan. I'd suggest that you obtain a copy of a wiring diagram or a workshop manual (try the public library) and hook up the temperature control and relay. A workshop manual will tell you how to check the switch and the relay (usually with a voltmeter or test light).
A couple more tips, if the coolant is getting too hot, try checking the thermostat. And if the coolant gets too hot, one way to try to cool the coolant (this is strictly a limp home for short distance option) is to close all the air vents into the cabin, wind the windows down, turn off the a/c and turn the heater to full HOT. The heater gets its heat from the coolant so when you turn it on you effectively create an auxilary radiator. Only problem is that if it's a hot day, the last thing you want to do is roast in the car.
Detailed discussion:
The radiator cooling fan is only needed when engine temperature rises above a predetermined level -- or when there is an increased load placed on the cooling system (as when running your air conditioner). The rest of the time, running the fan would be a waste of electrical energy so it is turned off. Electrical energy being supplied by the battery or the alternator - producing charge from the alternator uses power and effectively uses more fuel so hence it's off when not needed. And it's also additional noise.
At highway speeds, there is usually enough airflow through the radiator that a fan isn't needed. So the fan usually only operates when the vehicle is sitting in traffic, driving at slower speeds or at high duty applications. These would include climbing steep terrain (particularly at altitude where the air is less dense and cools less), towing, very heavy loads or running the air-conditioning.
On older applications, the electric fan is controlled by a temperature switch located in the radiator or engine. When the temperature of the coolant exceeds the switch's rating (typically 195 to 235 degrees F ie 80 to 110 degrees C), the switch closes and energizes a relay that supplies voltage to run the fan. It works the opposite way from a oven temperature switch.
The fan then continues to run until the coolant temperature drops back below the opening point of the switch. Most electric fans are also wired to come on when the A/C is on. Many vehicles also have a separate fan for the A/C condenser (dual fan systems). One or both fans come on when the A/C is on.
In newer vehicles with computerized engine controls, fan operation is regulated by the engine control module (the computer that runs the fuel injection, ignition etc). Input from the coolant sensor, and in many cases the vehicle speed sensor too, is used to determine when the fan needs to be on.
CAUTION: Many electric fans are wired to come on anytime the engine is above a certain temperature, regardless of whether the engine is running or not. This means the fan may come on after the engine has been shut off. So keep your fingers away from the fan at all times unless the battery or fan motor wires have been disconnected.
CHECKING THE FAN
Four things can prevent a fan from coming on when it should: a bad temperature switch or coolant sensor (or problem in the switch or sensor wiring circuit); a bad fan relay; a wiring problem (blown fuse, loose or corroded connector, shorts, opens, etc.); or a failure of the fan motor itself. Only the latter would require replacing the fan motor.
One way to check the operation of the fan motor is to jump it directly to the battery. If it spins, the motor is good, and the problem is elsewhere in the wiring or control circuit. Another check is to test for voltage with a voltmeter or test light at the fan's wiring connector. There should be voltage when the engine is hot and when the A/C is on.
Blink_32
04-18-2002, 07:31 AM
While the information you posted is correct in terms of TROUBLESHOOTING a malfunctioning fan and explaining how the whole cooling system works, it does not help me one bit. I already knew all of this.
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If you go back to my actual question all I want to do is hook up the fan to a manual switch. I know that at driving speeds the air flow is enough to keep temps down so the fan never comes on. Shoot, unless I'm stuck in stop and go traffic the temp never rises above C in this car. When I tested the wires to see which were Pos, Neg the temporarily spliced in wires got excessively hot. To me that means too much current (or amperage) was going through them.
.
How would I cure this problem? I am aware how to hook up a simple 2 position switch, but I want to make sure that the wiring or the switch does not get fried from too much current. How would I go about wiring it up for that purpose? Do I need a relay? A fuse wouldn't help because that just prevents X amount of amps from traveling through the wiring, I need to reduce the amount between the Pos teminal on the battery and to the fan but I don't know what component would do that.
.
If you go back to my actual question all I want to do is hook up the fan to a manual switch. I know that at driving speeds the air flow is enough to keep temps down so the fan never comes on. Shoot, unless I'm stuck in stop and go traffic the temp never rises above C in this car. When I tested the wires to see which were Pos, Neg the temporarily spliced in wires got excessively hot. To me that means too much current (or amperage) was going through them.
.
How would I cure this problem? I am aware how to hook up a simple 2 position switch, but I want to make sure that the wiring or the switch does not get fried from too much current. How would I go about wiring it up for that purpose? Do I need a relay? A fuse wouldn't help because that just prevents X amount of amps from traveling through the wiring, I need to reduce the amount between the Pos teminal on the battery and to the fan but I don't know what component would do that.
Tireburner
04-29-2002, 01:37 PM
Under the air intake tube is the thermal fan switch. It is in the water tube. two wires, (if I remember correctly) the wire colors are green/red and black/white. By touching the wires together (provided you have the right switch, and everything else is working properly) the electric fan will kick on (ignition must be on). You can wire a switch off of those two wires, or as I see in most cases of the fan not kicking on, replace the sensor.
Thyclenny
03-26-2010, 02:41 PM
Earth Hour 2010 comes about on Saturday 27 March and can be a worldwide call to action to each and every man or women, just about every small business as well as each and every neighborhood across the world.
It is known as a call to stand up, taking responsibility, for getting engaged and also steer the best way in direction of a eco friendly foreseeable future.
Are going to you take part?
It is known as a call to stand up, taking responsibility, for getting engaged and also steer the best way in direction of a eco friendly foreseeable future.
Are going to you take part?
Intuit
03-26-2010, 10:45 PM
I don't think he meant any insult Tireburner.
Basically what he's suggesting is, locate the hi and low fan relays, and wire in a 3-position switch (off, low, hi) that will charge the coil(s) and activate the relay(s). Using that method, you won't have to deal with any current related issues.
I have a '94 1.9L sedan model and the fan rarely runs except for when the compressor is run. So I had it for about 3 years before I ever heard it on "wind tunnel" speed. Prior to then, only heard it on low and moderate speeds.
Despite that all I've heard folks discuss is a high and low relay. Don't know if maybe the two combined create the third speed. Don't know if one wire at the fan is meant to serve as high, and the other as low only; or if the third wire is for monitoring fan rotational speeds. (like personal computers) But a schematic would shed some light on those Qs....
Basically what he's suggesting is, locate the hi and low fan relays, and wire in a 3-position switch (off, low, hi) that will charge the coil(s) and activate the relay(s). Using that method, you won't have to deal with any current related issues.
I have a '94 1.9L sedan model and the fan rarely runs except for when the compressor is run. So I had it for about 3 years before I ever heard it on "wind tunnel" speed. Prior to then, only heard it on low and moderate speeds.
Despite that all I've heard folks discuss is a high and low relay. Don't know if maybe the two combined create the third speed. Don't know if one wire at the fan is meant to serve as high, and the other as low only; or if the third wire is for monitoring fan rotational speeds. (like personal computers) But a schematic would shed some light on those Qs....
Intuit
03-26-2010, 10:50 PM
BTW, playing around with the horn relay and volt meter, is a great way to gain a better understanding of how relays work. (at least for me - had to do this while tapping in an alarm system)
denisond3
03-27-2010, 09:16 AM
But the fan in a 91 would be a two speed fan. The 3 leads to the motor are Ground, Winding 1, and Winding 2. On the low speed only the two leads would be involved, gnd. and one of the others. Same for high speed. And they shouldnt get warm´though if you had connected the wires for the two windings together they might. Would also burn out the brushes fairly quick. Mine has never come on for the high speed - probably because my a.c. is no longer working, so there isnt so much heat load under the hood.
Im assuming that some day I will have to replace the low speed and high speed fan relays - and I know there is a really good How-To on doing that. I even have the replacement relays in hand. At that time I will also add a switch to make the fan run, since the non-working a.c. means turning that on wont make the fan come on.
Im assuming that some day I will have to replace the low speed and high speed fan relays - and I know there is a really good How-To on doing that. I even have the replacement relays in hand. At that time I will also add a switch to make the fan run, since the non-working a.c. means turning that on wont make the fan come on.
denisond3
03-27-2010, 09:22 AM
As far as an ECO friendly future - Having an Escort that gets 40 mpg on the highway is part of my eco-ness. My pickup truck gets 25 mpg on the open road - its a jeep with the 2.5L four cyl. and a 5 speed. And I dont use a.c. in my cars.
The last (& only) new vehicle I ever bought was my 1968 BMW R69S, which I still have. It gets about 40 mpg. All of my other cars were bought dead AS-IS and fixed up by me. End of eco-ness.
The last (& only) new vehicle I ever bought was my 1968 BMW R69S, which I still have. It gets about 40 mpg. All of my other cars were bought dead AS-IS and fixed up by me. End of eco-ness.
Intuit
03-27-2010, 10:17 AM
But the fan in a 91 would be a two speed fan.
Ah, it's a 91. I guess they at some point added a speed for the later years.
One thing I meant to mention, is that a bad motor or motor with bad bearings may draw too much current. If there is a bad or corroded connection or damaged wiring that will also cause the connection or wiring to become hot.
Ah, it's a 91. I guess they at some point added a speed for the later years.
One thing I meant to mention, is that a bad motor or motor with bad bearings may draw too much current. If there is a bad or corroded connection or damaged wiring that will also cause the connection or wiring to become hot.
Davescort97
03-28-2010, 11:35 PM
As far as an ECO friendly future - Having an Escort that gets 40 mpg on the highway is part of my eco-ness. My pickup truck gets 25 mpg on the open road - its a jeep with the 2.5L four cyl. and a 5 speed. And I dont use a.c. in my cars.
The last (& only) new vehicle I ever bought was my 1968 BMW R69S, which I still have. It gets about 40 mpg. All of my other cars were bought dead AS-IS and fixed up by me. End of eco-ness.
denisond3: An immense amount of energy is required to manufacture a new car. Thanks for being green by keeping an older one running. I commend you.
The last (& only) new vehicle I ever bought was my 1968 BMW R69S, which I still have. It gets about 40 mpg. All of my other cars were bought dead AS-IS and fixed up by me. End of eco-ness.
denisond3: An immense amount of energy is required to manufacture a new car. Thanks for being green by keeping an older one running. I commend you.
AzTumbleweed
03-29-2010, 07:06 AM
Several years ago my radiator was clogged and my hi-speed fan came on when the temp gage got to the red. I don't have my manual in front of me but I was thinking that the single speed fan was for cars without A/C. I would do what a poster above said. Disconnect the temperature sensor and hook your toggle switch in to that. If it doesn't work then you probably need a new fan relay. As far as the warm wires go. Since they are what the factory put in it then certainly they would be of sufficient gage. As many of you know the hi-speed wire on the heater motor also gets warm. On my car I have a set of 100 watt halogen lights and I use a Chrysler headlight relay that I bought at NAPA. If you want to install your own relay you can buy one and make sure it'll handle the amount of amps that the cooling fan will reguire. I installed a circuit breaker at the battery where the power to my relay comes from. If there are actually two seperate relays then are they interchangable? If saw swap the wires around.
mightymoose_22
03-30-2010, 04:38 PM
You guys must not have noticed that this is an 8 year old thread... I'm sure the car is history by now.
AzTumbleweed
03-31-2010, 08:54 AM
You guys must not have noticed that this is an 8 year old thread... I'm sure the car is history by now.
Thanks for the info. I hadn't noticed. We've been wasting our time. :frown:
Thanks for the info. I hadn't noticed. We've been wasting our time. :frown:
stango95
04-07-2010, 05:45 PM
any suggestions on my ac in not coming on and the cooling fan is not coming on I replaced resistor in blower motor that is running perfect the 40 am fuse in engin box is good but put a teter on it and no power coming to fuse in engine is there another relay prior to that box like a circuit breaker 98 forst escort se 4 door
Selectron
04-08-2010, 12:46 PM
I don't have wiring diagrams for the '98 but it should be wired very similar, if not identical to, the '97. I assume that's the 40 amp Cooling Fan fuse that you've checked and at which you've found no voltage. It's fed from the 100 amp Main Fuse, but since that also feeds the fuel pump, if you have a running engine then the Main Fuse must be good.
You are checking for voltage correctly, eh - one lead of the tester to a known good ground point and then probe the fuse with the tester tip. If the fuse is still in the socket then it should have 12 volts on both legs, or if you pull the fuse and probe the empty socket then it should have 12 volts on one leg only. These are the power distribution diagrams for that section of the wiring:
'97 Escort power distribution - 01 (http://i180.photobucket.com/albums/x64/Selectron/Escort/97-power-distribution-01.png)
'97 Escort power distribution - 02 (http://i180.photobucket.com/albums/x64/Selectron/Escort/97-power-distribution-02.png)
You are checking for voltage correctly, eh - one lead of the tester to a known good ground point and then probe the fuse with the tester tip. If the fuse is still in the socket then it should have 12 volts on both legs, or if you pull the fuse and probe the empty socket then it should have 12 volts on one leg only. These are the power distribution diagrams for that section of the wiring:
'97 Escort power distribution - 01 (http://i180.photobucket.com/albums/x64/Selectron/Escort/97-power-distribution-01.png)
'97 Escort power distribution - 02 (http://i180.photobucket.com/albums/x64/Selectron/Escort/97-power-distribution-02.png)
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