Is your AC compressor grounded out? This guide will provide a step-by-step breakdown on how to diagnose this issue accurately and the ways to address it effectively.

Table of Contents
Tools You Will Need
Before you dive into diagnosing or fixing the AC compressor grounded out issue, gather the following tools:
Multimeter: An essential tool for electrical diagnostics. (You can get this AstroAI Multimeter Tester from Amazon now!)
Screwdriver: For opening the casing of the AC unit.
Insulated Gloves: Safety first! Always wear insulated gloves when working with electrical systems.
Wire Strippers: For preparing any wires if needed. (You can use this WGGE WG-015 Professional 8-inch Wire Stripper/wire crimping tool listed on Amazon)
How to Diagnose AC Compressor Grounded Out
Diagnosing a grounded AC compressor is a critical first step in resolving this issue. However, working with electrical components is inherently dangerous, so extreme caution is essential. Here’s a detailed, step-by-step guide on how to go about it:
Turn Off the Power: The first and most crucial step is to turn off all power to the air conditioning unit to prevent any electrical accidents. Locate the circuit breaker that corresponds to your AC unit and flip it to the ‘off’ position. Confirm that the power is off by trying to turn on the AC unit; it should not respond.
Access the Compressor: The compressor is generally located inside the outdoor unit of your AC system. Unscrew the fasteners that hold the unit’s cover in place, and carefully remove it. You will now see the compressor, which typically resembles a large, cylindrical metal object with electrical connections on the top or side.
Prepare Your Multimeter: For this step, you’ll need a multimeter set to measure resistance (Ohms, Ω). If you’re unfamiliar with how to set up your multimeter, refer to the instruction manual. Ensure your multimeter is calibrated and in good working condition before proceeding.
Perform the Grounding Test: Wear insulated gloves for protection. Take one probe of the multimeter and touch it to a clean, unpainted metal area on the compressor’s body. Use the other probe to touch each of the electrical terminals on the compressor one by one. A reading close to zero Ohms indicates that the compressor is grounded out. A higher reading suggests that the issue might be elsewhere.
Steps to Fix the AC Compressor Grounded Out Problem
If your diagnosis confirms that the compressor is grounded out, you’ll likely need to replace it. Repairing a grounded compressor is rarely effective and is not recommended due to the risk of recurrent failure. Here are the detailed steps to replace a grounded compressor:
Order a Replacement Compressor: Based on your AC unit’s make and model, order a compatible compressor. Verify its compatibility by checking the manufacturer’s specifications or consulting with a qualified technician.
Preparation: Just as in the diagnosis step, safety comes first. Turn off all power to the unit at the circuit breaker. Confirm that the power is off as described in the diagnosis section.
Remove Old Compressor: Open the AC unit to access the compressor. Take note of how all wires are connected to the old compressor for easier installation of the new one. Then, use appropriate tools to disconnect the electrical connections and any bolts or fasteners securing the old compressor to the unit. Carefully remove the compressor and set it aside.
Install the New Compressor: Place the new compressor in the exact position where the old one was located. Secure it using the appropriate bolts or fasteners. Reconnect the electrical connections as they were in the old compressor. If you took a photo or made a diagram of the old connections, refer to it for guidance.
Test the Unit: Before sealing the unit, turn the power back on at the circuit breaker and test the AC system. Make sure the new compressor runs smoothly and that the AC unit is cooling efficiently. Once you confirm the unit’s proper function, turn off the power again, and securely fasten the cover back on.
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AC Compressor Grounded: Easy Guide to Identify & Fix
When to Call a Professional
Electrical issues like a grounded out compressor are best left to professionals if you are not comfortable or skilled in handling them. Improper handling can not only damage the equipment but also be dangerous. If you’re not confident about your abilities to diagnose or replace a compressor, there is no shame in hiring a skilled technician to do the job safely and effectively.