Chicago summers are brutal. When temps hit 95°F with high humidity in July, a failing AC is not just uncomfortable — it's dangerous for kids, the elderly, and pets. The good news: most failures give you warning signs weeks before they happen.
The 7 Warning Signs
Warm or Room-Temperature Air From the Vents
Your AC is running but the air is lukewarm or barely cooler than the room. Don't just crank the thermostat lower — that won't fix anything and it runs your electric bill up.
- Low refrigerant from a leak — the system can't absorb heat without it
- Dirty condenser coil — the outdoor unit can't release heat if the coil is packed with debris
- Failed compressor — the heart of the AC; if it's out, no cooling happens at all
Grinding, Squealing, or Banging Sounds
A healthy AC runs quietly — a steady hum from the outdoor unit and airflow from the vents. Any unusual sound means a mechanical problem is developing.
- Grinding — motor bearings failing; left alone, the motor seizes
- Squealing — worn belt or off-balance blower wheel
- Banging on startup — loose component or compressor about to fail
- Hissing or bubbling — refrigerant leaking from a line
AC Turns On and Off Every Few Minutes (Short Cycling)
Short cycling — starting, running 2–5 minutes, shutting off, then starting again without reaching your thermostat setting — is one of the most damaging patterns for a compressor. Every cold start puts wear on it.
- Refrigerant leak causing pressure imbalance
- Clogged filter choking airflow, causing overheating and safety shutoff
- Oversized system — cools the thermostat sensor too fast, leaves the rest humid
- Failing capacitor — the component that starts the motors
Electric Bills Spiked Without a Change in Usage
If your ComEd bill this May is noticeably higher than last May and nothing has changed, your AC is working harder than it should. Dirty coils, low refrigerant, or a struggling compressor all force the system to run longer per cooling cycle. A well-maintained AC uses roughly the same electricity year over year under similar weather. A 15–20% or more spike in summer months warrants a tune-up inspection.
Some Rooms Are Much Warmer Than Others
If the first floor is comfortable but upstairs stays 10°F warmer regardless of runtime, you have an airflow or distribution problem. Most homeowners accept this as "just how the house is" — but it almost always gets worse over time.
- Blocked or closed vents cutting off airflow to certain areas
- Failing blower motor that can't push enough air through ductwork
- Duct leaks — conditioned air escaping into attic before reaching the room
- Low refrigerant reducing overall cooling capacity
Water Leaking Around the Indoor Unit
Your AC removes humidity from the air — that moisture drains out through a condensate drain line. Water pooling around the air handler means the drain is clogged or the drain pan is cracked. It's an easy fix caught early — left alone it causes water damage to ceilings and walls, and eventually triggers the safety float switch that shuts the whole system off.
Ice Forming on the AC Unit
Ice on the refrigerant lines or evaporator coil looks wrong — and it is. It means the coil is getting too cold, which happens when airflow is blocked or refrigerant levels are off.
- Turn the system off immediately — running with a frozen coil can destroy the compressor
- Switch the fan to "on" to help it thaw
- Replace the air filter if it's clogged
- Call a technician — the underlying cause won't fix itself
If none of those fix it, the problem is internal and needs a professional diagnosis.
Seeing Any of These Signs?
SAVA provides same-day AC diagnostics across Chicago and suburbs. We check refrigerant, electrical components, coils, and airflow — and tell you exactly what's wrong before touching anything.