HVAC Troubleshoot Guide
Follow the steps below to identify possible issues with your system
❄️ A/C Not Cooling
Thermostat set correctly?
Set to COOL and 3–5° below room temp.
Air coming from vents?
If no airflow: blower, breaker, float switch, or thermostat issue.
Outdoor unit running?
Possible capacitor, contactor, or electrical issue.
Dirty air filter?
Replace filter immediately.
Ice on system?
Turn OFF system, fan ON. Likely airflow or refrigerant issue.
🌬️ Weak / No Airflow
Dirty filter?
#1 cause. Replace filter.
Only some rooms weak?
Duct restriction or imbalance.
Weak everywhere?
Blower, coil, or major duct issue.
💧 Water Leaking
Clogged drain line?
Most common cause.
Ice present?
Frozen coil thawing overflow.
Still leaking?
Possible cracked pan or install issue.
⚡ System Not Turning On
Thermostat blank?
Check batteries, breaker, power.
Breaker tripped?
Reset once only.
Float switch tripped?
Drain pan full or clogged line.
🧊 Frozen System
Ice visible?
Turn OFF system immediately.
Dirty filter?
Common cause of freezing.
Still freezing?
Refrigerant or airflow issue.
🔌 Outdoor Unit Not Running
Thermostat calling?
Check COOL mode.
Disconnect on?
Verify outdoor disconnect.
Humming sound?
Likely bad capacitor.
🔋 Unit Humming / Not Starting
Humming but not running?
Failed capacitor.
Starts after delay?
Weak capacitor.
🔁 Short Cycling
Thermostat location?
Heat/sun exposure affects readings.
Filter clean?
Dirty filter can cause cycling.
Still cycling?
Refrigerant or control issue.
🧠 Thermostat Issues
Blank screen?
Replace batteries.
Unresponsive?
Wiring or control board issue.
🔊 Strange Noises
Rattling?
Loose parts.
Squealing?
Motor/bearing issue.
Banging?
Turn system off immediately.
💸 High Electric Bill
Filter changed?
Dirty filter increases runtime.
Running longer?
Efficiency issue possible.
No changes?
Check utility rates or new appliances.
