AC Fan Control

[BosnianLanos]

Need help from some electronic gurus.

The Lanos has 2 fans behind the radiator, one the actual radiator fan and one the AC fan. I know the Radiator fan kicks in at a certain temperature to keep the car from overheating, but I am unsure if the AC fan ever kicks in if you are not running AC. Making it dead weight.

So, first question. Does the AC Fan on the back of the radiator and condensor turn on if the AC isn't on?

If it does turn on without AC, I'll leave the system alone but if it won't turn on if the compressor is disengaged, I'm planning a little mod.

I was thinking about running a switch to the AC fan from the inside of the cabin so that I can turn on the fan whenever the car needs help with the cooling system, so that I can have both fans running just to cool the radiator. I mean, I don't really need the extra cooling since my car has never even nearly overheated, but I'd like to have backup if I ever need it.

I was thinking, what wiring should I run to operate the AC fan independently of the ECU. Should I run just a switched fused 12 Volt source to it or is there a better way to do it, wiring it through the relay or ECU. It'll be a cool little mod (seriously no pun intended) and it'll keep people wondering what all the little switches are in my car.

[MMamdouh]

both fans kick in regardless of the opreational status of the A/C.

when the A/C is on or the coolant temp is some 93C both fans kick in at low speed mode and if temp. rises to 97C then both fans switch to high speed mode.

here is an article that tells all about cooling fans we have:

The cooling fans are mounted behind the radiator in the engine compartment. The electric cooling fans increase the flow of air across the radiator fins and across the condenser on air conditioner (A/C)-equipped vehicles. This helps to speed cooling when the vehicle is at idle or moving at low speeds.

The main fan size is 320 mm (12.6 inches) in diameter with five blades to aid the airflow through the radiator and the condenser. An electric motor attached to the radiator support drives the fan.
A/C models have two fans - the main fan, and the auxiliary fan. The auxiliary fan is250 mm (9.8 inches) in diameter. Non-A/C models have only the main fan.

A/C OFF or Non-A/C Model

?The cooling fan(s) are actuated by the powertrain control module (PCM) in vehicles with an automatic transaxle or the engine control module (ECM) using a low-speed cooling fan relay and a high-speed cooling fan relay. On A/C-equipped vehicles, a series/parallel cooling fan relay is also used.

?The PCM or the ECM will turn the cooling fan(s) on at low speed when the coolant temperature reaches 93?C (199?F) and high speed at 97?C (207?F).

?The PCM or the ECM will change the cooling fan(s) from high speed to low speed at 94?C (201?F) and turn the cooling fans off at 90?C (194?F).

A/C ON

The PCM or the ECM will turn the cooling fans on at low speed when the A/C system is on. The PCM or the ECM will change to high speed when the coolant temperature reaches 115?C (239?F) or high-side A/C pressure reaches 1882 kPa (273 psi).

The cooling fans will return to low speed when the coolant temperature reaches 112?C (234?F) and high-side A/C pressure reaches 1448 kPa (210 psi).

Engine Cooling Fan Circuit Check - With A/C

Circuit Description:

The engine cooling fan circuit operates the main cooling fan and the auxiliary cooling fan. The cooling fans are controlled by the powertrain control module (PCM)/engine control module (ECM) based on inputs from the engine coolant temperature (ECT) sensor and the air conditioning pressure (ACP) sensor.

The PCM/ECM controls the low speed cooling fan operation by internally grounding the PCM/ECM connector terminal C13. This energizes the low speed cooling fan relay and operates the main cooling fan and the auxiliary cooling fan at low speed as the cooling fans are connected in a series circuit.

The PCM/ECM controls the high speed cooling fan operation by internally grounding the PCM/ECM connector terminal C13 and the PCM/ECM connector terminal C12 at the same time.

This energizes the low speed cooling fan relay, the high speed cooling fan relay, and the series/parallel cooling fan relay resulting in high speed fan operation as the cooling fans are now connected in a parallel circuit.

Diagnostic Aids

?If the owner complained of an overheating problem, it must be determined if the complaint was due to an actual boil over, or the engine coolant temperature gauge indicated overheating. If the engine is overheating and the cooling fans are on, the cooling system should be checked.

?If the engine fuse block fuses EF4 become open (blown) immediately after installation, inspect for a short to ground in the WI ring of the appropriate circuit. If the fuses become open (blown) when the cooling fans are to be turned on by the PCM/ECM, suspect a faulty cooling fan motor.

?The PCM/ECM will turn the cooling fans on at low speed when the coolant temperature is 97 ?C (207 ?F) . The PCM/ECM will turn the cooling fans off when the coolant temperature is 94 ?C (201 ?F) .

?The PCM/ECM will turn the cooling fans on at high speed when the coolant temperature is 101 ?C (214 ?F) . The PCM/ECM will change the cooling fans from high speed to low speed when the coolant temperature is 98 ?C (208 ?F) .

?The PCM/ECM will turn the cooling fans on at low speed when the A/C system is on. The PCM/ECM will change the cooling fans from low speed to high speed when the high side A/C pressure is 1882 kPa (273 psi ) then return to low speed when the high side A/C pressure is 1448 kPa (210 psi ). When the A/C system is on, the PCM/ECM will change the cooling fans from low to high speed when the coolant temperature reaches 117 ?C (244 ?F) then return to low speed when the coolant temperature reaches 114 ?C (237 ?F) .

?The cooling fan circuit can be checked quickly by disconnecting the PCM/ECM connector 2 and grounding the connector terminal C13. This should create low speed cooling fan operation with the ignition ON . By grounding the PCM/ECM connector terminals C13 and C12 and turning the ignition ON , high speed cooling fan operation should be achieved.

MMamdouh

[BosnianLanos]

It still says when the refridgerant reaches a certain pressure that they both go on. I have no freon in my car, so I guess the best way to be sure would be to drive around, put it in park, pop the hood, and see what is spinning.

Damn, I really wanted 3 switches on my dash, if what you say is true (which it probabally is) I'm only down to two.

Thanks a lot for your help.

[BosnianLanos]

My goal is to now wire both fans to a switch so that I can turn them on early to keep the temp down before the ECU ever turns them on at higher temps. I will leave the ECU controls intact, but if the switch is on, they will have more current and therefore operate at a higher speed than they normally would.

This will be cool because I will be able to have my fans on even if the car isn't on. This might help after a long drive.

I don't know why I am stuck on this mod, but usually when I get an idea in my head it goes through one way or the other.

I have a little wiring schematic set up and I will probabally attempt this tomorrow or on Tuesday.

[MMamdouh]

do you mean turning the fans on after you turn off the engine? if that is the case then it is a good idea as the engine keeps on radiating heat to the coolant when it is off yet the cooling fans and water pump are dead.

if you suggest doing that with the car on then you will go too low on the temp. so the ECU will think the engine is cold and it will rich your mixture and accordingly your MPG will be orse and your performance as well.

MMamdouh