cwylie

I noticed my tune my a/c clutch is just set to run all the time if the a/c is on. I threw an a/c belt recently and I was curious if that might be the cause. Do you all have your set to disable based on tps or rpm?

erick_e

Not sure I understand your question. The a/c clutch is designed to cycle on and off based off of high and low side pressure, but can run constantly. The air conditioning will not work unless the clutch is engaged to spin the compressor.

cwylie

So the current setup in HPtuners looks like never will disengage the a/c compressor regardless of throttle or RPM. Should it be? Is it bad to spin the compressor at fast?

schpenxel

Doubt that caused you to throw a belt. More likely an old/stretched belt and or old tensioner. Yeah, that's factory settings on 2006+. Surprised me too, but is what it is.

Easy enough to change if you'd like.

schpenxel

He's talking about @ WOT I assume. Earlier models turned off the AC while @ 100% throttle.

Or I could be totally wrong.

erick_e

Looks normal, as the BCM actually sends the signal to the ECM to cycle the a/c clutch on and off. The ECM will only allow it, if it meets those requirements otherwise it wouldn't allow the a/c clutch to engage.



Below is a description of how it works.

The A/C system is engaged by selecting any switch on the HVAC control module except the, A/C OFF switch. The A/C switch will illuminate, A/C OFF, when the A/C switch is selected. The HVAC control module sends a class 2 A/C request message to the body control module (BCM) for A/C compressor clutch operation. The BCM must communicate with the ECM in order for the A/C clutch to be engaged. The HVAC system uses a compact variable swash plate compressor. The following conditions must be met in order for the ECM to turn on the compressor clutch from the HVAC control module request:

• BCM will allow A/C operation if the following limits are within normal operating range

- A/C line pressure

- A/C refrigerant low temperature

- Ambient temperature

- Engine coolant temperature

- Battery voltage

• HVAC control module

- OAT temperature more than 1.5°C (35°F)

- Control module operating range 9 and 16 volts

• ECM

- Engine coolant temperature (ECT) is less than 128°C (262°F)

- Engine RPM is more than 0 RPM

- A/C pressure is between 2850 kPa (413 psi) and 204 kPa (30 psi).