Your home’s air conditioner is an essential appliance that keeps you cool and comfortable during the hot summer months. However, if your AC compressor stops working, it can lead to some serious discomfort. That’s why it’s important to know how to check if your AC compressor is working properly. There are a few simple steps you can follow to troubleshoot the problem.
First, check to make sure that the AC unit is turned on and that the thermostat is set to a cool temperature. If the unit is on and the thermostat is set correctly, but the air coming out of the vents is still warm, then the next step is to check the compressor. The compressor is usually located outside of your home, and it’s the part of the AC unit that actually cools the air. To check the compressor, simply turn off the AC unit and then turn it back on. If the compressor starts up and runs for a few minutes, then it’s probably working properly.
However, if the compressor doesn’t start up or if it runs for only a few seconds before shutting off, then there may be a problem. There are a few things that could cause the compressor to malfunction, such as a faulty capacitor, a bad contactor, or a refrigerant leak. If you’re not comfortable troubleshooting the problem yourself, you should call a qualified HVAC technician to take a look.
Verifying Power Supply to the Compressor
Before troubleshooting the compressor itself, it is imperative to confirm that it is receiving adequate power supply. Here are some comprehensive steps to verify the power supply:
1. Check the Circuit Breaker Panel
Begin by inspecting the circuit breaker panel to identify the breaker responsible for powering the AC unit. If the breaker has tripped, reset it and observe if the compressor starts operating. If the breaker trips again, it may indicate a faulty compressor or a short circuit in the wiring, warranting further investigation.
2. Examine the Disconnect Switch
Locate the disconnect switch, typically situated outside near the AC unit. Confirm that the switch is in the “ON” position, allowing power to flow to the compressor. If the switch is off, turn it on and check if the compressor initiates operation.
3. Inspect the Contactor
The contactor is an electromagnetic switch that controls the power supply to the compressor. Remove the front panel of the AC unit and locate the contactor. Check if the contactor is receiving power at the incoming terminals. If power is present, use a multimeter to test the outgoing terminals for continuity. A lack of continuity signifies a faulty contactor.
Inspecting the Capacitor
The capacitor is a key component in the AC compressor, responsible for starting and running the motor. A faulty capacitor can prevent the compressor from starting or operating efficiently, leading to cooling issues. To inspect the capacitor, follow these steps:
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Turn Off Power to the AC Unit
Ensure the AC unit is completely powered off at the electrical panel before proceeding.
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Locate the Capacitor
The capacitor is typically mounted near the compressor, enclosed in a cylindrical or rectangular housing.
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Check for Physical Damage
Examine the capacitor for any obvious damage, such as dents, cracks, or leaks. If any physical damage is found, the capacitor should be replaced.
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Measure Capacitance
Using a multimeter set to the capacitance setting, measure the capacitance between the terminals of the capacitor. Compare the measured value to the specified capacitance rating indicated on the capacitor. If the measured value is significantly lower than the specified rating, the capacitor is likely faulty and should be replaced.
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Replace Faulty Capacitor
If the capacitor is found to be faulty, it should be replaced with a new one of the same capacitance rating and voltage. When replacing the capacitor, ensure the polarity is correct by matching the markings on the capacitor with the terminals on the AC unit.
| Capacitor Inspection Checklist |
|---|
| – Turn off power to the AC unit |
| – Locate the capacitor |
| – Check for physical damage |
| – Measure capacitance |
| – Replace faulty capacitor |
Checking Compressor Contacts and Wiring
Inspecting the compressor contacts and wiring is crucial for ensuring proper AC functionality. Here’s a detailed guide:
Visual Inspection
Begin by visually examining the compressor for any visible damage or corrosion on the contacts or wiring. Look for loosened connections, frayed wires, or burned components.
Electrical Testing
Use a multimeter to test for electrical continuity and voltage. Disconnect the power source and set the multimeter to the appropriate voltage setting. Connect one probe to a compressor contact and the other probe to the corresponding wire terminal. A reading of zero ohms indicates continuity, while a non-zero reading indicates a break in the circuit.
Capacitor Testing
The capacitor plays a vital role in starting the compressor. To test it, disconnect the power and discharge the capacitor by touching both terminals with an insulated screwdriver. Use a multimeter set to the capacitance setting. Connect one probe to each terminal and observe the reading. A reading within 10% of the capacitor’s rated value indicates a healthy capacitor. If the reading is significantly lower or higher, it may need replacement.
Other Considerations
In addition to the above steps, consider the following:
- Check for proper grounding of the compressor and electrical system.
- Inspect the circuit breaker or fuse associated with the AC unit for any trips or blown fuses.
- Ensure that the refrigerant lines are properly connected and sealed.
By thoroughly checking the compressor contacts and wiring, you can diagnose and resolve any issues that may be affecting the performance of your AC system.
Listening for Compressor Noise
When an AC compressor is functioning, it will produce a humming or chattering sound. This sound is typically indicative of the compressor’s motor running and pressurizing the refrigerant. Conversely, if you notice an absence of this noise, it can be a sign that the compressor is not operational.
To check for compressor noise effectively, follow these steps:
- Turn off all other appliances in the house to minimize background noise.
- Stand near the outdoor AC unit.
- Listen for a humming or chattering sound.
- If you hear no noise, proceed with further troubleshooting steps to determine the cause.
Troubleshooting Compressor Noise Absence
If you do not hear any compressor noise, it could indicate one of the following issues:
| Problem | Possible Causes |
|---|---|
| Faulty Compressor | Internal damage, electrical failure |
| Capacitor Failure | Provides power to the compressor |
| Low Refrigerant Levels | Insufficient refrigerant pressure |
| Electrical Wiring Issues | Connections may be loose or damaged |
| Thermostat Malfunction | Not sending power to the compressor |
If you suspect any of these issues, it is recommended to contact a qualified HVAC technician for further diagnosis and repairs.
Feeling the Compressor for Vibration
If your air conditioner is not cooling as well as it used to, one possible cause could be a malfunctioning compressor. The compressor is the heart of the air conditioner, and it is responsible for circulating the refrigerant throughout the system. If the compressor is not working properly, it can cause the air conditioner to lose its cooling capacity.
One way to check if the compressor is working is to feel it for vibration. When the compressor is running, it will vibrate slightly. If you place your hand on the compressor and feel no vibration, it is likely that the compressor is not running.
Here are some additional tips for feeling the compressor for vibration:
- Turn on the air conditioner and let it run for a few minutes.
- Place your hand on the compressor.
- You should feel a slight vibration.
- If you do not feel any vibration, the compressor may not be running.
- If you are unsure whether or not the compressor is running, you can check the electrical panel to see if the circuit breaker for the air conditioner has tripped.
| Causes of Compressor Vibration | Solutions |
|---|---|
| Loose bolts or screws | Tighten the bolts or screws. |
| Damaged or worn bearings | Replace the bearings. |
| Bent or misaligned shaft | Straighten or align the shaft. |
| Unbalanced refrigerant charge | Adjust the refrigerant charge. |
| Damaged or worn compressor | Replace the compressor. |
Monitoring Refrigerant Pressure
Measuring refrigerant pressure is crucial for assessing the health of your AC compressor and refrigerant system. Here’s a step-by-step guide:
1. Safety Precautions
Always wear protective gear (gloves, safety glasses) and keep children and pets away during the process.
2. Choose the Right Gauge
Use a manifold gauge set with two gauges: one for high-pressure (red) and one for low-pressure (blue) refrigerant.
3. Connect the Gauges
Attach the high-pressure gauge to the service port on the discharge line of the compressor (usually closest to the condenser) and the low-pressure gauge to the service port on the suction line (usually closest to the evaporator coil).
4. Position the Gauges
Position the gauges vertically with the dials facing you. Ensure they are securely fastened to prevent leaks.
5. Open the Valves
Slowly open the valves on both gauges. The pressure readings will start to stabilize within a few minutes.
6. Interpreting the Readings
The expected pressure readings for your refrigerant type and system design should be available in the unit’s manufacturer’s literature. These readings may vary depending on the ambient temperature and system load. As a general guideline, the:
| Refrigerant Condition | High-Pressure Range (psi) | Low-Pressure Range (psi) |
|---|---|---|
| Undercharged | Below recommended range | Below recommended range |
| Properly Charged | Within recommended range | Within recommended range |
| Overcharged | Above recommended range | Above recommended range |
If the pressure readings are significantly out of range, it may indicate a refrigerant leak, compressor malfunction, or other system issues. Consult a qualified HVAC technician for further diagnosis and repairs.
Diagnosing the Start Relay
Checking the Relay with a Multimeter
Using a multimeter enables an accurate assessment of the start relay’s electrical integrity. Begin by setting the multimeter to the “ohms” or “continuity” function. With the power supply disconnected, access the relay terminals and touch the multimeter probes to the relay coils. If the relay is functioning correctly, the multimeter will display a low resistance value, typically below 100 ohms.
Testing the Relay with a Jumper Wire
A jumper wire can be used to bypass the start relay and test the compressor directly. Locate the terminals on the contactor that correspond to the start relay. Use insulated pliers or a jumper wire to connect these terminals. If the compressor starts, the start relay is likely faulty and needs to be replaced.
Visual Inspection
A visual inspection can reveal signs of damage or wear on the start relay. Check for burn marks, loose connections, or any physical damage to the casing. Discoloration or corrosion on the terminals can also indicate a potential problem.
| Symptom | Possible Cause |
|---|---|
| No power to the compressor | Faulty start relay |
| Compressor hums but doesn’t start | Start relay not engaging |
| Compressor runs intermittently | Intermittent start relay failure |
Troubleshooting the Thermostat
If your air conditioner is not cooling, one possible culprit is the thermostat. Here are some steps you can take to troubleshoot the thermostat:
- Check if the thermostat is set to “cool” mode.
- Make sure the thermostat is set to a temperature lower than the current room temperature.
- Check if the thermostat is properly connected to the AC unit.
- Clean the thermostat terminals.
- Replace the thermostat batteries.
Advanced Thermostat Troubleshooting
8. Check the thermostat’s wiring
The thermostat may not be receiving power if the wiring is faulty. To check the wiring, you will need to use a multimeter.
Set the multimeter to the “continuity” setting and touch the probes to the terminal screws on the thermostat. If the multimeter does not beep, then the wiring is faulty.
| Terminal | Wire Color | Function |
|---|---|---|
| C | Blue or Black | Common |
| R | Red | 24-volt power |
| W | White | Heating |
| Y | Yellow | Cooling |
| G | Green | Fan |
Examining the Circuit Breaker or Fuse
Safety precautious should be taken when inspecting the circuit breaker or fuse, ensure the power supply to the AC unit is turned off before proceeding. Locate the electrical panel, typically in the basement, garage, or a utility closet. Inspect the circuit breaker or fuse associated with the AC unit, which will have a label indicating its purpose.
- Circuit Breaker: Identify the circuit breaker that is tripped. Flip the breaker to the “on” position and observe if it remains on. If it immediately trips again, there may be an electrical fault in the AC system.
- Fuse: Inspect the fuse for any visible damage, such as a broken wire or blackened filament. Replace the blown fuse with a new fuse of the same amperage rating.
If you have checked the circuit breaker or fuse and both are functioning correctly, the problem may lie elsewhere in the AC system. It is recommended to contact a qualified HVAC technician for further troubleshooting and repairs.
Additional Troubleshooting Tips
If the circuit breaker or fuse appears to be in order, consider the following additional troubleshooting steps:
| Issue | Possible Cause | Solution |
|---|---|---|
| AC Unit Not Turning On | Power outage Loose electrical connections Faulty thermostat |
Check for power Inspect and tighten electrical connections Replace or reprogram the thermostat |
| AC Blowing Warm Air | Dirty air filter Frozen evaporator coil Low refrigerant levels |
Clean or replace the air filter Defrost the evaporator coil Call an HVAC technician for refrigerant check |
| AC Making Noise | Loose belt Bearings going out Damaged compressor |
Tighten the belt Lubricate or replace bearings Call an HVAC technician for compressor diagnosis |
Seeking Professional Assistance
If all troubleshooting efforts fail, it may be necessary to seek professional assistance. HVAC technicians possess the expertise, tools, and experience to diagnose and resolve complex AC compressor issues accurately and efficiently.
Hiring a qualified technician ensures:
- Accurate diagnosis and repair
- Warranty on parts and workmanship
- Peace of mind knowing the system is functioning optimally
| Signs of AC Compressor Malfunction | Possible Causes |
|---|---|
| Unusual noises (grinding, rattling, squealing) | Faulty compressor bearings, worn-out components |
| Warm or cool air blowing from vents | Low refrigerant levels, faulty compressor valve |
| Increased energy consumption | Inefficient compressor operation, faulty wiring |
| AC unit short-cycling (turning on and off frequently) | Oversized or undersized compressor, refrigerant leaks |
| Burning smell | Overheated or damaged compressor |
How to Check if AC Compressor Is Working
The AC compressor is the heart of the air conditioning system, and it is responsible for compressing and circulating the refrigerant. If the compressor is not working properly, the AC unit will not be able to cool your home effectively. There are a few simple steps you can take to check if your AC compressor is working.
1.
Check the power supply. Make sure that the AC unit is plugged in and that the circuit breaker is not tripped. If the unit is not receiving power, the compressor will not be able to operate.
2.
Check the refrigerant level. A low refrigerant level can cause the compressor to overheat and shut down. You can check the refrigerant level using a refrigerant gauge.
3.
Check the condenser coils. The condenser coils are located on the outside of the AC unit, and they help to cool the refrigerant. If the coils are dirty or blocked, the compressor will have to work harder to cool the refrigerant, which can lead to overheating and shutdown.
4.
Check the capacitor. The capacitor is an electrical component that helps to start the compressor. If the capacitor is faulty, the compressor will not be able to start.
5.
Check the contactor. The contactor is an electrical switch that connects the compressor to the power supply. If the contactor is faulty, the compressor will not be able to receive power.
If you have checked all of these things and the compressor is still not working, you may need to call a qualified HVAC technician to diagnose and repair the problem.
People Also Ask
How do I know if my AC compressor is bad?
There are a few signs that may indicate that your AC compressor is bad, including:
- The AC unit is not cooling your home effectively.
- The AC unit is making a strange noise.
- The AC unit is leaking refrigerant.
- The AC unit is tripping the circuit breaker.
How much does it cost to replace an AC compressor?
The cost to replace an AC compressor can vary depending on the make and model of the unit, as well as the labor costs in your area. However, you can expect to pay between $800 and $2,500 for a new compressor.
Can I replace an AC compressor myself?
Replacing an AC compressor is a complex task that requires specialized tools and knowledge. It is not recommended that you attempt to replace the compressor yourself unless you are a qualified HVAC technician.
