Air Conditioning Repair in Des Plaines and the Chicago Suburbs

AC running but blowing warm air

This is the call we get most often on the first hot stretch of the season. The indoor blower is moving air, so the house sounds like it is cooling, but the air at the registers is close to room temperature. That points at the outdoor side of the system: a condenser that is not starting, a failed run capacitor, a tripped breaker or blown fuse at the disconnect, a contactor that is not pulling in, or a system that has lost refrigerant charge.

A quick check you can safely make before calling: confirm the thermostat is set to cool with a set point below room temperature, look at the breaker panel and the outdoor disconnect, and check whether the filter is clogged. Beyond that, the outdoor unit carries line voltage and the capacitor stores a charge even with the power off, so diagnosis belongs with a technician.

Frozen evaporator coil and ice on the lines

Ice on the indoor coil or on the copper line outside is a symptom, not the problem itself. A coil freezes when it gets too cold for the amount of air passing over it — either airflow dropped or the refrigerant charge is low. A dirty filter, a closed-off return, a failing blower motor or a blocked coil all cut airflow; a leak drops the charge.

Running the system while it is frozen can damage the compressor, so the right first step is to switch the thermostat to off and set the fan to on, which thaws the coil using indoor air. Once it is clear, the underlying cause still has to be found, or it will freeze again within a day or two.

Electrical faults: capacitors, contactors, fan motors and boards

Electrical components fail more often than anything else in a residential air conditioner. A weak run capacitor is a common cause of a condenser that hums but will not start, or one that starts and trips the breaker. Contactors pit and stick, condenser fan motors seize or lose bearings, and control boards fail in ways that show up as intermittent operation.

We test under load rather than by appearance, because a capacitor can measure fine at rest and still collapse on startup. Where we find a component drifting out of tolerance, we tell you and let you decide whether to change it now or watch it.

Thermostat and control problems

Not every cooling complaint is the air conditioner. A thermostat with dead batteries, a bad connection at the sub-base, a miswired common wire after a smart-thermostat swap, or a stuck relay can all stop a cooling call from ever reaching the condenser. So can a tripped condensate float switch, which is designed to shut the system down when the drain pan fills.

We verify the call for cooling at the equipment before condemning parts. If the thermostat turns out to be the problem, it is usually a straightforward replacement or rewire rather than a repair to the air conditioner itself.

Refrigerant and leak diagnosis

Refrigerant is not consumed. A system that is low on charge has a leak somewhere — at a coil, a fitting, a service valve or the line set. Adding refrigerant without finding the leak means paying for the same repair again next season, so we look for the leak and give you the location and the cost of fixing it.

If your system uses R-22, be careful about how you approach this. R-22 has been phased out of production, supply comes from recovered and stockpiled material, and pricing reflects that. On an older R-22 system with a leak, adding refrigerant should be treated as a temporary measure to get through a specific situation, not a repair, and we cannot promise a leak will hold or that the refrigerant will stay available or affordable. When the leak is in a coil or the system is well into its second decade, we lay out the replacement option alongside the repair and let you compare the two.

Short cycling, weak airflow and uneven cooling

A system that starts and stops every few minutes is usually reacting to something: a restricted filter, an oversized unit, a dirty condenser coil, low charge, or a thermostat mounted where sun or a supply register hits it. Short cycling wears out compressors and leaves the house humid because the system never runs long enough to dehumidify.

Weak or uneven cooling between floors is more often a duct and airflow problem than an equipment problem. We measure temperature split and check static pressure, return capacity and blower performance before recommending anything, because replacing equipment does not fix an airflow restriction.

What a diagnostic visit actually includes

We start with what the system is doing, not with a parts list. A typical visit includes checking the thermostat call, verifying voltage and control power, testing the capacitor and contactor under load, inspecting the blower and filter, measuring temperature split across the coil, checking the condenser coil and condensate drain, and taking refrigerant readings where the symptoms point that way.

You get the findings in plain language, the options that make sense, and the price before the repair begins. If the honest answer is that the repair is not worth it on a system near end of life, we will say so and show you what replacement looks like instead.

• Thermostat call and control voltage verified at the equipment
• Capacitor, contactor and fan motor tested under load
• Filter, blower and return airflow checked
• Temperature split measured across the evaporator coil
• Condenser coil, disconnect and condensate drain inspected
• Refrigerant readings and leak investigation where symptoms indicate it

Repair or replace

Age plus repair history is the practical test. A system in its first decade with a single failed component is almost always worth repairing. A condenser in its mid-teens that has needed a capacitor one summer and a fan motor the next, or one that is leaking refrigerant, is a different calculation — especially if it uses a phased-out refrigerant.

When it is close, we give you both numbers and let you decide. There is no pressure either way, and we will repair equipment we would not personally choose to keep if that is what you want to do this season.