Rad Fan Off

[eric sakai]

I keep A/C is on all the time. I was told that's why radiator fan is also on all the time.

But if car is going 50 mph for some time, shouldn't the air speed keep the radiator temperature down so the radiator fan does not come on?

I'm thinking the radiator core is old and not able to keep the radiator temperature down unless fan is on.

Thank you.

[theflea42]

If I'm not mistaken. one of the fans will always be running when the A/C is running. The other fan will kick on and off as necessary.

[Moto-Mojo]

Funny you ask this today. I'm tuned and the fans come on earlier (lower temp than stock) than they used to. I did notice today that they run at a low speed all the time, until it gets hot. Then they kick into high. I'm in CA and it was only about 52 degrees here today.

Nothing wrong with my core that I know of.

[gtstorey]

Originally Posted by Moto-Mojo

Funny you ask this today. I'm tuned and the fans come on earlier (lower temp than stock) than they used to. I did notice today that they run at a low speed all the time, until it gets hot. Then they kick into high. I'm in CA and it was only about 52 degrees here today.

Nothing wrong with my core that I know of.

It pretty easy to get the fan settings wrong when changing them in the tune. They might not be setup just right. No good reason for them to be running at low speed all of the time. Just adding wear to them.

[CamaroCracka]

From what I understand, a fan is always on when the AC is on. My Silverado is the same way. There is a thread where NotA45 explains how the three relays work to bring the fans on in stages.

[1JEWLDSSRS]

Originally Posted by CamaroCracka

From what I understand, a fan is always on when the AC is on. My Silverado is the same way. There is a thread where NotA45 explains how the three relays work to bring the fans on in stages.

Agreed as well.

[Mouse330]

Camaro has dual fans, A primary fan and a secondary fan. The primary fan is responsible for normal cooling operation, The secondary fan will kick in when the AC is activated or the engine temperature exceeds a certain threshold around 221 low 235 high. The fans are pulse width modulated(PWM) through the PCM in % duty cycle.

[1JEWLDSSRS]

Originally Posted by DarylKidd

Thanks for the info, I will keep it in mind.

^^^^ lol,

[acammer]

There is a painful amount of mis-information in this thread.

1. Fans are always on with air conditioning - false. There are two conditions the engine monitors and uses to decide when to run the fans - coolant temperature and air conditioning system pressure. From factory, the SS cars will turn the fans on low at 221*F of coolant temperature, or 1,350kpa of AC pressure. Fans will move to high speed at 228*F of coolant temp or 1,850kpa of AC pressure.
   
   Now, AC pressure on any sort of day where you need AC is typically going to keep the fans busy most of the time when the car is not moving, and with enough airflow through the condenser will cycle less at cruising speeds. But, simply turning the AC on does not mean you will always get fans.
   
   
2. Fans run independently of one another - false. The fan circuit is controlled by three solenoids. Each fan has a solenoid that can send it power 12v power, and the third solenoid switches the fans from series to parallel operation.
   
   On low, the fans are both powered by 12v from a single solenoid, and run in series. On high, the fans are split into parallel, and each received 12v independently. This scheme accomplishes two things. First, it provides a low and a high speed for operation. Secondly, it provides redundancy in the system so that if one of the solenoids should fail you will still have 1 fan that remains operational.
   
   
3. Fans are pulse width modulated - false. Per the explanation above, the fans are not pulse width modulated, but have discrete switched 12v control. This can also be validated in the tune under System > Hardware > Fan Type where you'll find Discrete is set, not any of the PWM options.

Hopefully that clears up some misinformation.

[Mouse330]

Yes sir you are right, I was going off memory of a typical GM cooling fan operation. Its a 3 relay system not solenoid like you are saying.

The engine cooling fan system consists of 2 electric cooling fans and 3 fan relays. The relays are arranged in a series/parallel (S/P) configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans receive positive voltage from the cooling fan relays which receive battery positive voltage from the underhood fuse block.


In low speed operation, the ECM applies ground to the coil side of the cooling fan low speed relay. This energizes the coil and applies voltage directly to the right cooling fan through the switch side of the low speed relay. The right cooling fan is connected in series to the left cooling fan through the de-energized series/parallel (S/P) cooling fan speed control relay. The series circuit operates both fans at low speed.


In high speed operation, the ECM applies a ground to the coil side of the cooling fan low speed relay, the S/P cooling fan speed control relay, and the cooling fan high speed relay. When energized, the high speed fan relay applies voltage directly to the left cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the S/P speed control relay provide ignition voltage and a direct path to ground for the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.

[0stones0]

Originally Posted by acammer

There is a painful amount of mis-information in this thread.

1. Fans are always on with air conditioning - false. There are two conditions the engine monitors and uses to decide when to run the fans - coolant temperature and air conditioning system pressure. From factory, the SS cars will turn the fans on low at 221*F of coolant temperature, or 1,350kpa of AC pressure. Fans will move to high speed at 228*F of coolant temp or 1,850kpa of AC pressure.
   
   Now, AC pressure on any sort of day where you need AC is typically going to keep the fans busy most of the time when the car is not moving, and with enough airflow through the condenser will cycle less at cruising speeds. But, simply turning the AC on does not mean you will always get fans.
   
   
2. Fans run independently of one another - false. The fan circuit is controlled by three solenoids. Each fan has a solenoid that can send it power 12v power, and the third solenoid switches the fans from series to parallel operation.
   
   On low, the fans are both powered by 12v from a single solenoid, and run in series. On high, the fans are split into parallel, and each received 12v independently. This scheme accomplishes two things. First, it provides a low and a high speed for operation. Secondly, it provides redundancy in the system so that if one of the solenoids should fail you will still have 1 fan that remains operational.
   
   
3. Fans are pulse width modulated - false. Per the explanation above, the fans are not pulse width modulated, but have discrete switched 12v control. This can also be validated in the tune under System > Hardware > Fan Type where you'll find Discrete is set, not any of the PWM options.

Hopefully that clears up some misinformation.

+1

[acammer]

Originally Posted by Mouse330

Yes sir you are right, I was going off memory of a typical GM cooling fan operation. Its a 3 relay system not solenoid like you are saying...

You're spot on - relay is a much more appropriate term. You went on to describe the system well. It's not complicated, and it's natural redundancy is simple but effective.