|
|
|
|
Joined: Feb 2005
Posts: 1
Newbie
|
OP
Newbie
Joined: Feb 2005
Posts: 1 |
I have a 1998 Contour GL with a 2.0L, 4-Cyl, Zytec Engine. The car's coolant gauge read "zero," and the dual radiator fans stopped working altogether after my mechanic changed the radiator coolent (flushed radiator and "winterized" it). I went back to the shop, and the mechanic said that the temperature sensor/sender unit that runs the temperature gauge had gone out. He replaced it. I drove the car home. I noticed that the radiator's dual fans were not working as the radiator temperature gauge's indicator needle was nearly into the red. I took the car back to the same mechanic, and he said that the dual fan (low speed, 5-pronged) relay had gone out. He replaced it. I drove home, and the overheat problem started all over again. I haven't verified that the radiator fan relay has burned out again, but for sure, the dual fans are OFFLINE altogether and not coming on at all-- to keep the radiator temperature down to a normal/non-overheated level. Any troubleshooter eagles out there want to comment on this problem? Pleeeeeeeze! Thanks for Your Help! Doug engshopper888@yahoo.com
|
|
|
|
|
Joined: Oct 2004
Posts: 36
New CEG\'er
|
|
New CEG\'er
Joined: Oct 2004
Posts: 36 |
Best guess is you have a wire connection issue. A bad connection causes high resistance, which in turn results in low voltage to the fan, the fan then draws more amps to compensate which stresses the relay.
Troubleshooting involves measuring the voltage at the fan, if it is low then you trace back towards the source in order to find where the missing volts are. If the voltage at the fan is normal, then you would want to put an ammeter in-line to see how much current is flowing, if the current is too high the fan itself could be bad.
|
|
|
|
|
Joined: Sep 2002
Posts: 1,788
Hard-core CEG\'er
|
|
Hard-core CEG\'er
Joined: Sep 2002
Posts: 1,788 |
Originally posted by big_mack:
Best guess is you have a wire connection issue. A bad connection causes high resistance, which in turn results in low voltage to the fan, the fan then draws more amps to compensate which stresses the relay.
This is not possible. Basic Ohm's Law. E=I X R. Applied voltage (to the circuit) is constant at battery voltage. If resistance in the load circuit increases, current must decrease proportionately.
Quote:
if the current is too high the fan itself could be bad.
This, on the other hand, is correct. A DECREASE in the load resistance will cause a proportionately larger current flow.
Suggest that the low speed resistor circuit be checked. If that dropping resistor opens, the fans will not engage until the upper trigger temp (around 215-220 F ) is reached. The resistor is physically located on the bottom of the radiator shroud. It has been the subject of several in-depth discussions.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
|
|
|
|
|
Joined: Oct 2004
Posts: 36
New CEG\'er
|
|
New CEG\'er
Joined: Oct 2004
Posts: 36 |
Good logic, except a circuit with a motor in it is not purely resistive. If there is enough voltage present the motor will try to start, start-up causes a current spike which stresses components (like the relay) or blows a fuse. If the connection is bad enough, the motor will do nothing even though there is nothing wrong with the motor itself.
|
|
|
|
|
Joined: Sep 2002
Posts: 1,788
Hard-core CEG\'er
|
|
Hard-core CEG\'er
Joined: Sep 2002
Posts: 1,788 |
Originally posted by big_mack:
Good logic, except a circuit with a motor in it is not purely resistive. If there is enough voltage present the motor will try to start, start-up causes a current spike which stresses components (like the relay) or blows a fuse. If the connection is bad enough, the motor will do nothing even though there is nothing wrong with the motor itself.
It's not logic, it's physics.
Any current spike will be limited by any in-circuit resistance.
If a faulty (high resistance) connection is present, the motor cannot draw current adequate. Any inductive reactance would, in this instance, likely be coincidental. In any event, the reactance would add to the load making the total load greater which, according to Ohm's Law, will decrease total current in the circuit.
If the motor is drawing excessive current at startup, it most likely is defective due to seized bearings or a faulty connection between the brushes and the commutator shaft. Shorted windings are another possibility.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
|
|
|
|
|
|
|
