1. [Home](/) 2. [Guides](/guides/) 3. Air conditioning through an Ohio summer # Air conditioning through an Ohio summer Southwest Ohio summers are hot and sticky, and your air conditioner has to handle both. Here is how the system works, what keeps it healthy, and what to do when it struggles. ## Key takeaways - An air conditioner removes humidity as well as heat, so a system that is sized correctly and runs in steady cycles feels more comfortable than an oversized one. - Refrigerant is sealed in the system and is not used up. If it is low, there is a leak, and finding it is a job for a certified technician. - A clean filter, a clear condenser and a spring tune-up prevent most no-cool calls. - Bigger is not better. Sizing should come from a load calculation, not from the size of the old unit. - Hot second floors are usually an attic, duct or airflow problem, and there are several ways to fix them. ## How air conditioning handles humid weather Summers in Southwest Ohio are hot, but the humidity is what makes a house feel miserable. An air conditioner does two jobs at once. It lowers the air temperature, and it pulls moisture out of the air. Warm indoor air passes over a cold coil inside the system, gives up its heat, and the water vapor in it condenses on the coil. That water runs out through the condensate drain, and the cooled, drier air goes back through your ducts. The outdoor unit, called the condenser, is where the heat leaves your house. Refrigerant carries heat from the indoor coil to the outdoor coil, and a fan blows it away. If anything in that loop is restricted, whether a clogged filter, a dirty outdoor coil or a low refrigerant charge, the system runs longer and cools less. Humidity matters for the house as well as for comfort. Air that stays damp feels clammy, can smell musty, and can support mold on walls, in closets and in basements. Many health and building sources suggest keeping indoor humidity between 30 and 50 percent. A system that runs in longer, steady cycles removes more moisture than one that blasts on and shuts off quickly. ## Refrigerant basics Refrigerant is not fuel. It circulates in a sealed loop and should last as long as the system does. If your system is low on refrigerant, it has a leak somewhere, and topping it off without finding the leak only buys time. Federal rules require technicians to be certified to buy and handle refrigerant, and the work needs gauges, recovery equipment and proper procedures. This is not a do-it-yourself job, and kits sold for it are not a substitute for a diagnosis. The type of refrigerant matters too. Older systems used a refrigerant that is no longer produced for new use, which can make repairs on a leaking older system more involved. Newer systems use different refrigerants, and the industry continues to change which ones are used in new equipment. If you are weighing a repair against a replacement, ask your HVAC contractor which refrigerant your system uses and what that means for service. Signs of a leak include ice on the copper lines, a hissing sound, oily residue at the fittings, and cooling that gets weaker over weeks rather than all at once. ## Condenser care and the spring tune-up The outdoor unit sits in your yard, and it collects whatever the season throws at it: cottonwood fluff, grass clippings, leaves, pollen and mulch. All of that restricts airflow across the coil. Keep a couple of feet of open space around the unit, trim back shrubs and aim the mower discharge away from it. To clean it, turn the power off at the disconnect box next to the unit first. Then rinse the coil gently with a garden hose from the outside. Do not use a pressure washer, because the aluminum fins bend easily and bent fins block airflow. If the fins are packed with debris, or the fan is not turning, that is a job for a technician. Watch the pad, too. Clay soils across much of the region swell when wet and shrink when dry, and freeze-thaw cycles can shift things. A condenser that tilts or sinks can strain the refrigerant lines and the compressor. A spring tune-up, scheduled before the first run of hot days, is worth more than a call in July when every contractor is busy. A technician should check refrigerant pressures and temperatures, electrical connections, the capacitor and contactor, coil condition, the blower, the condensate drain and thermostat operation. You can handle the filter, the clear space around the unit and a quick check that the drain line is not dripping or backed up. See our [maintenance service](/services/maintenance/) for what a visit typically covers. ## Sizing and SEER2 ratings Many homeowners assume a bigger air conditioner cools better. It does not. An oversized system cools the air quickly, shuts off, and leaves the moisture behind. You get short cycles, a clammy feel, uneven rooms and extra wear on the compressor. Proper sizing comes from a load calculation, often called a Manual J. It accounts for your insulation, windows, which way the house faces, air leakage and the ducts. Square footage alone is not enough, and neither is copying the size of the old unit. Older homes in the region have often had added insulation, new windows or an addition since the original system went in, so the right size today may be different. Cooling capacity is measured in tons, and one ton equals 12,000 BTU per hour. Efficiency is rated by SEER2, which compares the cooling a system delivers over a season with the electricity it uses. A higher number means less electricity for the same cooling, but it is only one factor. Duct condition, installation quality and sizing affect real-world results as much as the label. Our guide to [SEER2 ratings](/guides/air-conditioning-guide/seer-ratings-explained/) explains how to compare systems. ## Common summer breakdowns Most no-cool calls trace back to a short list of causes: - **Dirty filter or blocked airflow.** Restricted air reduces cooling and can freeze the indoor coil. - **Frozen evaporator coil.** Ice on the lines or weak airflow from the vents. - **Clogged condensate drain.** Water backs up, and many systems shut off when a safety switch detects it. - **Failed capacitor or contactor.** The unit hums, or the outdoor fan or compressor will not start. - **Dirty condenser.** The system runs constantly and cools poorly on hot afternoons. - **Refrigerant leak.** Cooling slowly fades and ice may form. - **Thermostat or power problems.** Wrong settings, dead batteries or a tripped breaker. Some checks are safe for you: the thermostat settings, the filter, open vents, and resetting a tripped breaker once. If it trips again, stop. Anything involving refrigerant, or electrical parts inside the unit, belongs to a professional. Capacitors can hold a dangerous charge even with the power off. If the coil is frozen, turn the cooling off and let it thaw rather than running it. For a step-by-step list, read [AC running but not cooling](/guides/air-conditioning-guide/ac-not-cooling/), or schedule [AC repair](/services/ac-repair/). ## Keeping second floors cool Heat rises, and in a two-story house the upstairs also sits directly under an attic that can get far hotter than the outdoor air. Add long duct runs to the farthest rooms, and the bedrooms often end up the warmest part of the house. The fixes usually start with the building. Attic insulation and air sealing around hatches, light fixtures and wiring penetrations reduce the heat that reaches the ceiling. Older houses often have less insulation than current practice calls for. Next comes the ductwork: leaks in an attic duct blow cooled air into the attic, and crushed or undersized runs starve the rooms at the end. If the building and ducts are sound, options include adjusting airflow balance, adding a return upstairs, zoning the system with a separate thermostat for each floor, or adding a ductless mini-split for the room that never cools. Window shades and ceiling fans help at little cost. Read [why your upstairs is hotter than your downstairs](/guides/air-conditioning-guide/upstairs-too-hot/) for how to sort out the cause, and see ductless mini-splits if one room is the problem. ## When to repair and when to plan a replacement A single failed part on a system that has otherwise run well is usually worth repairing. Repeated breakdowns, rising noise, a system that struggles on hot days even after a tune-up, or a leak on an older refrigerant type are signs it is time to start planning. Replacing an air conditioner on your schedule, in spring or fall, gives you time to compare written proposals. Replacing it in a heat wave does not. When you do compare, ask each HVAC contractor how they sized the system, whether they inspected the ducts, which refrigerant it uses and what the SEER2 rating is. If you want an inspection before deciding, you can [contact a contractor](/contact/) to look at your system and your ducts together. ## Frequently asked questions How often should I change my air filter in summer? Check it monthly during cooling season and replace it when it looks gray and clogged. Many one-inch filters need changing every one to three months, and homes with pets or a lot of dust need it sooner. Thicker media filters last longer, but should still be checked. What temperature should I set my thermostat to in summer? Pick a setting that is comfortable and that the system can hold on the hottest days. Raising it a few degrees when you are away saves energy, but very large setbacks can leave the house humid and make the system work hard to recover. Should I cover my outdoor unit? Do not cover it with a solid lid or tarp in summer, and never run it covered. In winter, some homeowners place a breathable cover on top only to block falling debris, but a cover is not needed. Keeping the area clear of leaves and debris is the better habit. Do I really need a tune-up every year? A yearly check before cooling season catches worn capacitors, loose connections, dirty coils and drain problems before they cause a breakdown. It also gives you a record of how the system is aging, which helps you plan a replacement. 6 min read. ### Want us to handle it? Monroe Heating & Air works in Monroe, Franklin, Middletown, Trenton, Springboro, Mason, Maineville, Miamisburg. [Get a quote](/contact/)[Call (513) 540-4890](tel:+15135404890) ### In this guide - [AC running but not cooling: common causes](/guides/air-conditioning-guide/ac-not-cooling/) - [Why your upstairs is hotter than your downstairs](/guides/air-conditioning-guide/upstairs-too-hot/) - [SEER2 ratings explained simply](/guides/air-conditioning-guide/seer-ratings-explained/) ### Related services - [Air Conditioning Repair & Replacement](/services/ac-repair/) - [Tune-Ups & Maintenance Plans](/services/maintenance/) ### Service areas - [Monroe](/areas/monroe/) - [Franklin](/areas/franklin/) - [Middletown](/areas/middletown/) - [Trenton](/areas/trenton/) - [Springboro](/areas/springboro/) - [Mason](/areas/mason/) - [Maineville](/areas/maineville/) - [Miamisburg](/areas/miamisburg/) ### Other guides - [Furnaces and winter heating in Southwest Ohio](/guides/furnace-guide/) - [Heat pumps, humidity and indoor air quality](/guides/heat-pumps-and-air-quality-guide/) ## Call us at (513) 540-4890 or send a quote request and we will take it from there. [Get a quote](/contact/) [Call (513) 540-4890](tel:+15135404890) --- **Monroe Heating & Air** · 101 E Elm Street, Suite C, Monroe, OH 45050 · (513) 540-4890 · inbound@monroeheatingandair.com [Get a quote](/contact/) · [Services](/services/) · [Guides](/guides/) · [FAQ](/faq/)