AutoCodes – Generic – P1EC9

P1EC9 Code - A/C Compressor Motor Instantaneous High Current

Quick Answer

The AC compressor function is to provide refrigerant flow in the AC refrigerant loop to help cool down the cabin, help dehumidify the air in a defrost mode and help maintain the battery temperature. Common causes include Faulty A/C Compressor Motor, A/C Compressor Motor harness is open or shorted, A/C Compressor Motor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1EC9 indicates A/C Compressor Motor Instantaneous High Current.
Common causes: Common causes include Faulty A/C Compressor Motor, A/C Compressor Motor harness is open or shorted, A/C Compressor Motor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,693

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 25, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1EC9 Description

The AC compressor function is to provide refrigerant flow in the AC refrigerant loop to help cool down the cabin, help dehumidify the air in a defrost mode and help maintain the battery temperature. Rather than a more typical pulley, the A/C compressor uses a 3-phase alternating current, high voltage electric motor to operate. It has an on-board inverter that takes High Voltage direct current from the vehicle's High Voltage Battery and inverts it to alternating current for the motor. The AC compressor shall be activated when any of the three following events occur:
- The customer pushes the AC button
- The HVAC control, in AUTO mode, requests the electric AC compressor on to help in cooling the cabin or removing moisture in the defrost mode
- The High Voltage Battery Thermal System requests the AC compressor on to help maintain the battery temperature
The Hybrid/EV Powertrain Control Module 2 uses values from the A/C refrigerant pressure transducers, A/C refrigerant thermistor, duct temperature sensors, ambient air temperature sensor, passenger compartment temperature sensor, evaporator temperature sensor, battery cell temperature sensors, battery coolant temperature sensors and battery coolant pumps to determine the speed at which the compressor will operate. This speed request message is sent from the Hybrid/EV Powertrain Control Module 2 to the A/C compressor control module via GM LAN message.

OBDII Code P1EC9 - A/C Compressor Motor Instantaneous High Current - AutoCodes.com — P1EC9 Code - A/C Compressor Motor Instantaneous High Current

What does this mean?

What are the Possible Causes of the DTC P1EC9?

Faulty A/C Compressor Motor
A/C Compressor Motor harness is open or shorted
A/C Compressor Motor circuit poor electrical connection

How to Fix the DTC P1EC9?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1EC9 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Information for Specific Makes

P1EC9 Buick — A/C Compressor Motor Instantaneous High Current
P1EC9 Cadillac — A/C Compressor Motor Instantaneous High Current
P1EC9 Chevrolet — A/C Compressor Motor Instantaneous High Current
P1EC9 GMC — A/C Compressor Motor Instantaneous High Current
P1EC9 Saturn — A/C Compressor Motor Instantaneous High Current

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1EC9 Code

1. What does the OBDII code P1EC9 mean?

P1EC9 indicates that the A/C compressor motor is experiencing an instantaneous high current condition, which could damage the system if unresolved.

2. What are the common symptoms of code P1EC9?

Symptoms may include reduced or no air conditioning performance, a loud noise from the A/C compressor, or the A/C system shutting down entirely.

3. What causes the P1EC9 code to appear?

Common causes include a shorted A/C compressor motor, high electrical resistance in the wiring, or a fault in the A/C system's control module.

4. Can I still drive my car with a P1EC9 code?

Yes, but driving with this code may result in no air conditioning and could potentially damage the A/C compressor if the issue is not addressed promptly.

5. How is the P1EC9 code diagnosed?

A technician will use a scan tool to retrieve freeze frame data, inspect the A/C compressor motor and wiring, and measure electrical currents to determine the source of the problem.

6. How do you fix the P1EC9 code?

Repairs may involve replacing the A/C compressor motor, repairing damaged wiring, or reprogramming the A/C control module if it is faulty.

7. Can a blown fuse trigger the P1EC9 code?

Yes, a blown fuse in the A/C system can cause electrical issues that may result in this code being triggered.

8. How much does it cost to fix the P1EC9 code?

Repair costs vary but typically range from $500 to $1,500, depending on whether the A/C compressor motor needs replacement or if it's a simpler wiring or module issue.

9. Can a weak battery cause the P1EC9 code?

A weak or failing battery can sometimes lead to electrical irregularities that might contribute to this code, though it's not the most common cause.

10. Is the P1EC9 code related to refrigerant levels?

Not directly. While low refrigerant levels can cause A/C performance issues, this code specifically refers to an electrical problem in the A/C compressor motor.