P06A1: Variable A/C Compressor Control Circuit Low

Variable-displacement A/C compressors change their swash-plate stroke via an electric control valve: a PWM current sets the crankcase pressure and thus the output. Where the engine module drives this valve (Ford's 'EVDC' compressors 2013–2019), it monitors the circuit; where the climate control module drives it (Hyundai, VW/Audi, GM), faults appear in that module instead. CARB requires monitoring only where the A/C affects engine control. P06A1 means the control valve circuit is too low – a short to ground, or the driver sees ground potential with the output off; shorted coil turns are another cause. No manufacturer document available to us names P06A1 itself; the description follows P06A0 and the Ford EVDC system. The compressor then delivers no controlled output.

Medium severity. Can I keep driving?Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.

Symptoms

A/C cools weakly or not at all
Code stored

Most likely causes

Valve control wire shorted to ground (chafing at compressor or engine)
Shorted turns in the control valve
Moisture or corrosion in the compressor connector
Engine module driver faulty

What to check, in order

Start with the simplest. You can tick off each step.

Check the oil level and condition before anything else
With the connector unplugged, check whether the signal wire is making contact with ground.
Check the solenoid valve's connector
Compare commanded and actual angles in live data
Test the solenoid valve and its filter, if it has one
Check the engine timing if there is chain noise

Good to know

Repair difficulty: medium

What each character of P06A1 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
6: Control modules and outputs
A1: Specific fault in that system

Frequently asked questions

Can I keep driving with code P06A1?

Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.

What causes code P06A1?

The most common causes are: valve control wire shorted to ground (chafing at compressor or engine); shorted turns in the control valve; moisture or corrosion in the compressor connector.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.