engine overheating cooling fan issues
#1
engine overheating cooling fan issues
hot weather here in saint louis, anyone know how to get both fans on at the same time without the a/c on. my car runs great in reasonable weather, the intercooler is obviously affecting the airflow temp through the radiator. temp climbs to almost overheating on 95 degree plus days and as soon as i turn on the a/c the second fan kicks in, temp comes down. i can do the same thing with the heater on, but darn it gets hot. I need both fans to run without the a/c on. Anyone can help i would appreciate it.
thanks
jim
thanks
jim
#2
Boost Pope
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Option 1: http://www.miata.net/hakuna/parallel...%20wiring.html
The above may potentially blow the fan fuse and/or decrease the life of the fan relay. The "proper" way to do this mod would be to conjoin the control signals for the two relays, however on the 1.6 this is not easily done as the same relay drives both the A/C fan and the A/C clutch. Try option #1 first, and if that doesn't work, I'll draw you a picture of how to modify the harness to install an additional fan relay for the A/C fan.
-OR- just fix whatever is causing the overheating in the first place.
The above may potentially blow the fan fuse and/or decrease the life of the fan relay. The "proper" way to do this mod would be to conjoin the control signals for the two relays, however on the 1.6 this is not easily done as the same relay drives both the A/C fan and the A/C clutch. Try option #1 first, and if that doesn't work, I'll draw you a picture of how to modify the harness to install an additional fan relay for the A/C fan.
-OR- just fix whatever is causing the overheating in the first place.
#3
Option 2 - Post 7 - Oops NB
https://www.miataturbo.net/useful-saved-posts-8/parallel-fan-wiring-instructions-1316/
https://www.miataturbo.net/useful-saved-posts-8/parallel-fan-wiring-instructions-1316/
#9
Boost Pope
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Everything has resistance. Wire, fuses, relay contacts, terminals, they are all resistors.
As current passes through a resistor, there is a voltage drop across the resistor. As current increases, the voltage drop increases. The formula for this is V = I x R (V = voltage drop in olts, I = current in amps, R = resistance in ohms). Any voltage which is "dropped" across the resistance is essentially lost, it is unable to power the load.
I have no idea what the actual numbers are, but let's say that one fan draws 10A, the supply voltage is 14v, and the resistance across the whole fan circuit (fuse, relay, wiring, interconnects) is 200 milliohms (two tenths of an ohm.) In the case of a single fan, 10 x .2 = 2, so from the original 14v supply, the fan is only seeing 12v.
Now, throw a second fan on the line. 20 x .2 = 4, which means that the fans are now seeing only 10v (14 - 4).
Annoyingly, this relationship isn't linear, either. That voltage which is being dropped is generating heat in the conductors and contacts. As the temperature of a conductor increases, so does its resistance. So more drop = more resistance = more drop = more resistance = more drop (...) until eventually a point of equilibrium is reached.
(This is how light bulbs work, incidentally. When cold, they draw many amps. After a few tens of millisecons, as the filament becomes very hot, its resistance shoots up and current drops to the "rated" level. Were it otherwise, light bulbs would simply explode.)
(It's also the basic operating principle behind hot-wire MAF sensors. The air passing over the wire cools it, resistance drops, current increases. Airflow increases, more cooling, less resistance, more current. Airflow drops, less cooling, more resistance, less current.)
Like I said, I'm just pulling these numbers out of the air- could be more, could be less. But that's essentially what's going on.
#10
Joe,
would you post the wiring diagram you mentioned to correctly wire the fans together?
#11
Don't have a specific diagram. I didn't do it.
I Went back to the two fans set up as OEM and decided to pull the AC clutch connection off if I needed more. I didn't need more. Didn't overheat again.
Next time I go to the track I will disconnect the clutch wire and be ready if I need more cooling.
I Went back to the two fans set up as OEM and decided to pull the AC clutch connection off if I needed more. I didn't need more. Didn't overheat again.
Next time I go to the track I will disconnect the clutch wire and be ready if I need more cooling.
#16
Let me explain a bit more. Before the turbo, intercooler, the car would NEVER heat up at all. After the install, and only on hot days do I see the temp gauge rising up too much. Obviously the addition of the intercooler in the front of the radiator is causing either an airflow restriction or just enough heat passes out from it directly into the radiator and the one fan just can't keep up with the additional heat. I can't see any difference in timing or boost or anything to make me think otherwise. Thanks for the help
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