Help Please!

[bb66]

Hi all, I have a 2010 ss camaro and as soon as I turn on the AC, both cooling fans under the hood come on full blast until I turn the car off (extremely loud). It happens no matter what the outside temp is The temp sensor has been replaced and the gauge is always normal. I've tested the fan relays and they're fine. No error codes come up with a scan either. Does anyone know what could cause this? Any help would be greatly appreciated!

[tbirdtbird]

I am not so sure I would call this a problem.
The fans are coming on to force air not only thru your radiator, but in the case of AC, more importantly, thru the AC condenser, which sits in front of the rad. If there is no air blowing across your condenser, your AC pressures will rise very high, your AC cooling will be very compromised (like almost no cool air at all, and the hi pressure switch on the AC system will shut the AC off, unless you blow the high side AC hose first and lose all your refrigerant.

The condenser's job is to transfer the heat that was absorbed from the cabin to the outside of the car. All AC does is transfer heat from one space to another. So the space outside the car gets hotter while the space inside the car gets cooler.

In short, if this were my car, I would be rather pleased that those fans were coming on. They are supposed to.

[JohnHere]

I agree with the previous comments.

One question, though: Do you recall whether the fans came on like that previously?

[Tim]

Pretty sure both fans kit into high speed when the a/c is turned on.

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.

[bb66]

They didn’t always run full blast like they are now. Also, I have a coworker with the same car and his aren’t running on high.

[ArgosyRV]

I don't know if this applies to your situation, but I have an LT1 swapped 74 Camaro and the fans run on high at startup when the ecm is running/stuck in open loop. I have had this happen and the cause was a bad MAF sensor? in my case it also did not throw any ecm codes for some reason.

[bb66]

It only does it when I turn the ac on, everything works perfectly fine except the fans are on high.

[tony1963]

I would think on a vehicle of that age, the computer should be regulating the fan speed by pulse width modulation of the ground signal to the fan motor.

Using a modern scan tool, I would recommend connecting to that system and see if a fan percentage command, or something like that, is displayed. If it is, then see if it goes directly to 100% and, if it does, you likely have something electronic malfunctioning.

I have also seen systems where the display showed as OFF, LO, MED, HI. Scan tool is your friend.

[bb66]

Do you happen to know where the high pressure switch is located on a 2010 ss Camaro? I see the low side, but can't even find the accumulator.

[Tim]

Other than the posts on the discharge line?


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