Ac Unit Will Not Come On

Introduction

It’s a hot day, and your AC unit decides to take a break. An AC unit that won’t turn on can be frustrating and uncomfortable, especially during peak summer months. This problem can stem from simple issues like a tripped breaker to more complex problems within the unit. Ignoring this problem can lead to further damage and increased repair costs, so let’s troubleshoot!

Common Causes of AC Unit Will Not Come On

Here are some common reasons why your AC unit might not be turning on:

• Tripped Circuit Breaker: AC units require a lot of power, and a tripped breaker is a common cause.
• Thermostat Issues: The thermostat might be set incorrectly, have dead batteries, or be malfunctioning.
• Power Switch Off: Sometimes, the outdoor unit’s power switch is accidentally turned off.
• Dirty Air Filter: A clogged air filter restricts airflow, causing the unit to overheat and shut down.
• Overload Protector Tripped: The overload protector can trip if the compressor overheats.
• Frozen Evaporator Coil: Restricted airflow can cause the evaporator coil to freeze, stopping the AC.
• Condenser Fan Motor Failure: If the fan isn’t running, the unit can overheat.
• Wiring Problems: Loose or corroded wiring can disrupt the power supply.
• Refrigerant Leaks: Low refrigerant can prevent the compressor from starting.
• Capacitor Problems: The capacitor helps start the compressor and fan motor. If it’s bad, the unit won’t start.

Symptoms Checklist

Use this checklist to help pinpoint the problem:

• The AC unit is completely unresponsive no lights, no sound.
• The thermostat is on, but the AC isn’t blowing air.
• The AC unit hums but doesn’t start.
• The circuit breaker trips when you try to turn on the AC.
• The air filter is visibly dirty.
• Ice is visible on the indoor or outdoor unit.

How to Fix AC Unit Will Not Come On Step-by-Step Guide

Follow these steps to troubleshoot your AC unit:

1. Check the Thermostat: Make sure it’s set to COOL and the temperature is set lower than the current room temperature. Replace the batteries if necessary.
2. Inspect the Circuit Breaker: Locate the circuit breaker for your AC unit in your electrical panel. If it’s tripped (in the OFF or middle position), flip it all the way to OFF and then back to ON.
3. Check the Outdoor Unit’s Power Switch: Locate the disconnect box near the outdoor unit and make sure the power switch is in the ON position.
4. Inspect the Air Filter: Remove the air filter from your indoor unit and check if it’s dirty. Replace it with a clean filter if needed.
5. Reset the Overload Protector: Some AC units have a reset button on the outdoor unit. Look for a small red or black button and press it.
6. Check for Ice on the Evaporator Coil: If you see ice on the indoor unit’s evaporator coil (usually accessible behind the air filter), turn off the AC and let the ice melt completely. This can take several hours. Ensure the filter is clean after.
7. Inspect the Condenser Fan: Make sure the fan blades are free from obstructions and can spin freely. Turn off the power to the unit before touching the fan.
8. Check for Obvious Wiring Problems: Look for loose or corroded wires around the AC unit and thermostat. If you see any, consult a qualified electrician.
9. Listen for Unusual Noises: If you hear humming or clicking sounds but the unit doesn’t start, the capacitor might be failing. (Further testing required – see below)
10. Test the Capacitor (If Comfortable): WARNING: Capacitors store high voltage even when the unit is off. Only proceed if you understand electrical safety. Use a multimeter to test the capacitor’s capacitance. If the reading is significantly lower than the rating printed on the capacitor, it’s likely bad. (Although not recommended to replace yourself – this verifies component as cause).
11. Allow Unit to Rest: If the unit seems to have overheated, turn it off and allow it to cool down for a few hours before attempting to restart it.
12. Confirm Thermostat Wiring: Open the thermostat and verify the wires are securely connected to the correct terminals. Consult your thermostat manual for the correct wiring diagram.

Fix the Issue Without Buying Parts

Here are some things you can try that don’t require buying anything:

• Reset the System: Turn off the AC at the breaker for 30 minutes, then turn it back on. This can sometimes reset the system and clear minor errors.
• Clean the Outdoor Unit: Remove any leaves, grass, or debris that may be blocking the outdoor unit. Gently rinse the fins with a garden hose (low pressure).
• Inspect Air Ducts: Check visible sections of your air ducts for leaks or damage. Seal any small leaks with duct tape.
• Ensure Proper Airflow: Make sure vents are open and not blocked by furniture or curtains.
• Regular Maintenance: Regularly clean or replace your air filter (every 1-3 months) and keep the outdoor unit clear of debris.

When Replacement Might Be Necessary

If none of the troubleshooting steps work, or if your AC unit is very old (15+ years), it might be time for a replacement. Replacing an AC unit can cost anywhere from $3,000 to $7,000+, depending on the size and efficiency of the unit. Common parts that fail and might warrant replacement of the whole unit due to age/efficiency issues are: the compressor, the fan motor, and the circuit board.

Safety Warning

• Always turn off the power to the AC unit at the breaker before performing any troubleshooting or maintenance.
• Do not touch any electrical components with wet hands.
• If you are not comfortable working with electricity, consult a qualified HVAC technician.
• Be cautious when working near the outdoor unit, as the fins can be sharp.

Tools You May Need

• Screwdriver (Phillips and flathead)
• Multimeter (for testing electrical components – if comfortable)
• Flashlight
• New air filter
• Garden hose (for cleaning the outdoor unit)

FAQ

Here are some frequently asked questions about AC units that won’t turn on:

• Q: Why does my AC unit keep tripping the circuit breaker? A: This could be due to an overloaded circuit, a faulty compressor, or a wiring problem. Consult a qualified electrician.
• Q: How often should I change my air filter? A: Typically, every 1-3 months, depending on usage and air quality.
• Q: Why is my AC unit blowing warm air? A: This could be due to low refrigerant, a dirty air filter, or a malfunctioning compressor.
• Q: Can I fix a refrigerant leak myself? A: No, refrigerant leaks should only be repaired by a licensed HVAC technician.
• Q: What does a frozen coil mean? A: A frozen coil indicates restricted airflow. Check and replace filter. If problems persist call HVAC pro.

Conclusion

Troubleshooting an AC unit that won’t turn on can seem daunting, but by following these steps, you can often identify and fix the problem yourself. Remember to prioritize safety and consult a qualified technician if you are unsure about any part of the process. Hopefully, you can get your AC back up and running quickly, allowing you to enjoy a cool and comfortable home. However, don’t hesitate to call a professional if needed; they have the expertise and tools to diagnose and repair more complex issues.

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