Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Regulating The Air Conditioning (A/C) Compressor
The air conditioning (A/C) compressor is controlled by the engine control module (ECM) (4/46) on request from the climate control module (CCM) (3/112) via the controller area network (CAN). When the engine control module (ECM) receives a signal from the climate control module (CCM) to activate the air conditioning (A/C) compressor, the engine control module (ECM) grounds the circuit for the relay coil for the A/C compressor. See also: AIR CONDITIONING (A/C) RELAY
The relay (2/22) closes the circuit between the integrated relay/fusebox in the engine compartment and the clutch for the air conditioning (A/C) compressor (8/3). The air conditioning (A/C) compressor which has a variable cylinder displacement is always running during normal driving. Displacement in the compressor is regulated by a solenoid which is controlled by the engine control module (ECM).
The engine control module (ECM) regulates the solenoid (displacement) in relation to the driver's and vehicles' different driving styles. Starting the engine, moving off and acceleration means more regulated displacement so that the A/C compressor has less possible effect on engine torque. The climate control module (CCM) controls all functions in the climate control module which are related to the vehicle interface with the driver and passenger. I. E. the climate control buttons on the dashboard environment panel.
The climate control module (CCM) transmits information to the engine control module (ECM), which determines what must be prioritized. For example, the air conditioning (A/C) compressor in certain extreme cases is switched off completely, regardless of the climate control module (CCM) request. This is to prevent negative engine performance and to protect the air conditioning (A/C) system. As well as the information from the climate control module (CCM), the engine control module (ECM) controls the air conditioning (A/C) compressor based on the information from:
- Air conditioning (A/C) pressure sensor (high pressure side) (7/8)
- the throttle position (TP) sensor (6/120)
- the engine coolant temperature (ECT) sensor (7/16).
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.