Wiring advice

[Kooldino]

I have a problem with my car overheating while stopped on occasion.

I'm hoping it could be fixed by flowing more air over the radiator.

The radiator has 2 fans attached to it, one that comes on when the coolant hits a certain temp, and the other comes on when you turn the A/C on, and the car is moving below a certain speed.

I'd like to rewire it somehow so that the A/C fan comes on when it normally would, as well as when the primary radiator fan comes on. How can I do this?

Here are the following cases:

Primary Fan ON, A/C ON, A/C Fan ON
Primary Fan ON, A/C OFF, A/C Fan ON

Primary Fan OFF, A/C ON, A/C Fan ON
Primary Fan OFF, A/C OFF, A/C Fan OFF

[LvR]

Fans are on the same radiator so 2 short wires needed only - connect "color" to "color" on both fans - ie - black to black and red to red ..............?

Result expected - temp reached both fans come on, and if AC is switched on irrespective of temp the fans are also both on.

[Brian Ellis]

Wouldn't it be better to find out the cause of the overheating (possibly a sticky thermostat), and remove said cause, rather than try to botch up a workaround?

[LvR]

Wouldn't it be better to find out the cause of the overheating (possibly a sticky thermostat), and remove said cause, rather than try to botch up a workaround?

I seem to remember a turbo being mentioned elsewhere..........

[cjolley]

1, Tap from the hot wire of the radiator fan through a relay's control circuit to ground.
2, Run a line from hot through the relay's controled curcuit to the hot side of the AC fan.

The AC fan won't care wherther it is getting juice from it's normal circuit or the one controled by the relay, or both.
And the current draw of the relay's control circuit shuldn't have much, if any effect on the radiator fan.

UNLESS a test of the AC fan hot wire shows that it is grounded when the ingnition switch is off, or the fan's oun relay is off. (The former is entirely possible)
In that case what I suggested would produce a short circuit if the AC fan was off and the engine fan came on.
* and so would LvR's so beware!

@Brian: Spoil sport.

Chuck

[Gurm]

This is a criminally poor idea. If your car is overheating, there's a REASON why it's overheating. I, too, would guess the thermostat. Adding more fans is NOT a good solution to the problem.

[cjolley]

Actualy I just assumed he has already tested and/or simply replaced his thermostat already.

Considering it has a turbo and therefore (I also assume) lower compression pistons, it is a puzzle why it would overheat while idling.

Maybe the engine fan's motor is dragging and it is not really spinning up to it's required speed, to move enough air.

[ZokesPro]

This is on your Mazda MP3? The sweet modded machine?

Yeah, I too would check the thermostat, sounds like it's stuck shut. Could be the fluid level that's low.

[Kooldino]

Fans are on the same radiator so 2 short wires needed only - connect "color" to "color" on both fans - ie - black to black and red to red ..............?

Result expected - temp reached both fans come on, and if AC is switched on irrespective of temp the fans are also both on.

So are you saying that I can do this (see pic)?

And you're saying that both will come on whether the AC is on OR if the primary comes on?

What happens in the condition that the AC fan would normally be on along with the primary fan? Would it hurt anything?

[Kooldino]

Wouldn't it be better to find out the cause of the overheating (possibly a sticky thermostat), and remove said cause, rather than try to botch up a workaround?

Well, the thing is that the car is fine while it's moving. I can beat the piss out of it, and it's almost impossible for it to break 200*F. But once it's still at idle for awhile, it's a totally different story.

[Kooldino]

UNLESS a test of the AC fan hot wire shows that it is grounded when the ingnition switch is off, or the fan's oun relay is off. (The former is entirely possible)
In that case what I suggested would produce a short circuit if the AC fan was off and the engine fan came on.
* and so would LvR's so beware!

@Brian: Spoil sport.

Chuck

So to test this, I want to just run a test wire from the + side on the battery to the + side of the fan, while the car is off?

[Kooldino]

This is a criminally poor idea. If your car is overheating, there's a REASON why it's overheating. I, too, would guess the thermostat. Adding more fans is NOT a good solution to the problem.

Well, some say that it's the fact that I can run the car hard, and then the engine bay bakes once I'm idling. Other think I may have a pinhole in my headgasket, which is making the combustion gases heat up the coolant.

[cjolley]

TEST THE LEADS!
If the relays that turn these fans on ground a fan's hot wire when they (the relay) are "off"
then you will short out your car.
It will catch fire and burn up


Ok, maybe not that, but it wouldn't be pretty.

You HAVE replaced the thermostat haven't you?

[Kooldino]

Actualy I just assumed he has already tested and/or simply replaced his thermostat already.

Considering it has a turbo and therefore (I also assume) lower compression pistons, it is a puzzle why it would overheat while idling.

Exactly. I'm baffled too.

Maybe the engine fan's motor is dragging and it is not really spinning up to it's required speed, to move enough air.

Well, i'm running an aftermarket Spal radiator fan, which is very thin (sounds like a Delta 9K CPU fan), and I'm not sure how it compares to the stock fan at moving air.

[Kooldino]

This is on your Mazda MP3? The sweet modded machine?

Yup.

Yeah, I too would check the thermostat, sounds like it's stuck shut. Could be the fluid level that's low.

The fluid isn't low...and I recently changed it as part of my diagnosis. Distilled water, 60/40 with radiator coolant, and a bottle of water wetter for good measure.

I'm wondering if I could just pull the thermostat out completely and run without it for a test.