In the Chicago area, you're asking your car's climate system to handle extremes. July temperatures above 90°F put real demand on your A/C compressor and condenser. January temperatures well below zero test your heating system, defroster, and every rubber component.

A climate system that's been properly maintained handles both. One that's been neglected tends to fail at the worst moment — a heat wave with no A/C, or a January morning with no defroster.

Here's what a year-round maintenance approach looks like.

Spring  — preparing for A/C season

Check refrigerant : If your A/C didn't cool well last fall, don't wait until a 90-degree day to find out it still doesn't. A refrigerant pressure check tells you if the level is adequate. If it's low, a leak check should be done before recharging — otherwise you'll lose the refrigerant again and be back in the same situation.

Run the system : Turn on the A/C for 10–15 minutes and confirm it's blowing cold. Listen for unusual noises — particularly grinding or squealing when the compressor clutch engages, which points to a compressor problem. Check that the air volume from the vents is what you'd expect.

Change the cabin air filter : A clogged cabin air filter reduces airflow through the evaporator and makes the A/C less effective. If it hasn't been changed in a year or you can't remember when it was changed, spring is a good time to do it. It's typically a 10–15 minute job.

Summer — running the system hard

During summer, the A/C runs under its heaviest load. If a problem was developing slowly, summer heat is often when it becomes obvious.

Watch for sweet smell : A musty smell from the vents in humid weather typically means mold or bacteria on the evaporator — more common in cars that are left with the A/C off for extended periods in humidity. An aerosol treatment can address mild cases; in worse situations, a full evaporator treatment is needed.

Monitor cooling performance : A system that cools inconsistently — cold then warm, or only cold at certain RPMs — points to refrigerant pressure problems, a cycling switch, or compressor issues.

Fall — transitioning to heat season

Test the heater : Turn on the heat before it's cold enough outside that you actually need it. Confirm it warms up to a reasonable temperature within a few minutes of driving. If the engine reaches normal operating temperature (check your temperature gauge) but heat is weak, investigate — it may be a clogged heater core or a blend door issue.

Check the rear defroster: Rear defrost uses an electrical element grid on the glass. Test it specifically — it's separate from your HVAC system. If sections aren't clearing, individual grid elements may be broken and can often be repaired with a conductive repair kit.

Windshield washer fluid: Switch to a winter formulation before temperatures drop below freezing. Summer fluid freezes in the lines and reservoir. This is a two-minute change that prevents a genuine visibility hazard.

Winter — peak demand on heat

Front defroster: Your front defroster uses the HVAC system (often with A/C compressor engaged to dehumidify the air, which is why the A/C button should stay on in defrost mode). If it's slow to clear, the climate system may need attention.

Watch for temperature gauge behavior: An engine that takes excessively long to warm up in cold weather, or a temperature gauge that sits lower than normal, can indicate a thermostat that's stuck open. The heater will also underperform with a stuck thermostat.

At ProAuto, we service A/C and heating systems year-round. We handle both R-134a and R-1234yf refrigerants and do full system diagnostics rather than just recharging and hoping.

ProAuto | 6100 W Dempster St, Morton Grove, IL 60053 | (847) 232-7777

Serving Morton Grove, Skokie, Niles, Glenview, Northbrook, Evanston, Wilmette, Winnetka, Des Plaines, and Park Ridge.