Why Your Cincinnati AC Keeps Breaking Down, and How to Fix it

We need our air conditioning in Cincinnati’s hot and humid summers to stay comfortable, but our weather puts ACs under stress. A broken AC unit is, unfortunately, common, but can often be fixed with some simple troubleshooting.

Here are some of the most frequent issues we see here at Jansen Heating & Cooling, the probable causes for each, and what you can do on your own before calling an air conditioning contractor.

The AC won’t come on

Possible causes:

• Tripped circuit breaker
• Faulty thermostat
• Loose wiring or bad capacitor

Troubleshooting:

1. Check the breaker box for a tripped switch.
2. Ensure the thermostat is set to “Cool” and the temperature is lower than the room temp.
3. Inspect the AC shut-off switch (should be near the unit).
4. If the AC is still unresponsive, the capacitor or control board may need repair.

Warm air is coming out of your vents

Possible causes:

• Incorrect thermostat settings
• Clogged air filter
• Refrigerant leak
• Dirty evaporator or condenser coils

Troubleshooting:

1. Set the thermostat to “Cool” and Auto (not “Fan”).
2. Replace or clean the air filter.
3. Clean the outdoor unit’s condenser coils.
4. If you suspect the refrigerant is low (you hear a hissing sound or the coils are frozen), call an HVAC technician.

The air flow seems weak

Possible causes:

• Clogged air filter
• Blocked or leaking ducts
• Blower motor issue

Troubleshooting:

1. Check the filter and replace if it is dirty.
2. Open all supply and return vents for better circulation.
3. Inspect your ductwork for leaks or blockages.
4. If the blower motor isn’t running, it may need professional servicing.

AC runs constantly or turns on and off rapidly (short cycles)

Possible causes:

• Dirty air filter
• Oversized or undersized unit
• Inappropriate thermostat placement

Troubleshooting:

1. Replace dirty air filters to improve airflow.
2. Check if the thermostat is near a heat source (sunlight, lamp) and relocate if needed.
3. If the AC frequently turns on and off within minutes, the unit may be oversized or have a faulty compressor.

Water is leaking from the air conditioner

Possible causes:

• Clogged condensate drain line
• Frozen evaporator coil
• Low refrigerant levels

Troubleshooting:

1. Clear the drain line with vinegar or a wet/dry vacuum.
2. Check for frozen coils (if they are frozen, turn off the AC and let them thaw).
3. If leaking continues, a professional may need to check for low refrigerant.

 Odd noises

• Loud buzzing/humming could be an electrical issue or failing capacitor
• Rattling usually means loose parts, or a fan blade issue
• Hissing is caused by a refrigerant leak
• Clicking indicates a faulty relay switch

Troubleshooting: 

1. Tighten any loose screws or panels.
2. Call a professional AC repair company if the noise is persistent or related to electricity or refrigerant.

The AC freezes up

Possible causes:

• Dirty air filter restricting airflow
• Low refrigerant levels
• Faulty blower fan

Troubleshooting:

1. Turn off the AC and let the ice melt before restarting.
2. Replace dirty filters and clean the evaporator coil.
3. If freezing continues, a technician should check your AC’s refrigerant level.

If the issue persists

The good news is, many problems can be solved by changing the air filter or doing a little cleaning. But if the issue doesn’t go away, an HVAC professional from Jansen Heating & Cooling can diagnose and fix deeper problems.

To avoid breakdowns at inconvenient times (like in the summer), be sure to schedule a spring tune-up with your HVAC contractor.

If you join Jansen’s Maintenance Club, you’ll get a reminder when it’s time, and other benefits like priority service, discounts, service documentation (in the event that you want to sell your home), longer system life and more.