If your air conditioner is running but blowing warm air, you are not alone this time of year. Shoemaker Heating and Cooling LLC, based in Honey Brook, PA at (610) 671-3595, fields this exact call throughout July from homeowners across New Holland, Earl Township, and the Route 23 corridor of eastern Lancaster County. The good news is that warm air from a running AC almost always points to one of a handful of causes, and most are fixable in a single visit.
New Holland sits along a stretch of farmland and older borough housing where many homes had central air added well after original construction. Retrofitted duct systems, undersized equipment, and aging refrigerant lines are common in this market, and each can contribute to the warm air problem homeowners are noticing right now.
The Most Common Reasons Your AC Blows Warm Air
A dirty or clogged air filter is the single most common cause. When airflow across the indoor evaporator coil is restricted, the coil can drop below freezing and ice over. Once that happens, the system stops delivering cold air even though the blower is still running. Shoemaker technicians recommend checking your filter monthly during peak summer use as part of routine AC maintenance.
Low refrigerant is the second most frequent cause, and it always means there is a leak somewhere in the system. Refrigerant is sealed in a closed loop and does not get consumed through normal use. A system running low will struggle to remove heat, cycle longer than normal, and eventually blow room temperature or warm air even with the compressor running.
A dirty outdoor condenser coil can also cause this problem. The condenser releases the heat your system pulls out of your home, and if it is coated in grass clippings, pollen, or debris, it cannot release that heat efficiently. This is especially common in New Holland and Earl Township, where homes near farm fields see more airborne debris settle on outdoor units than homes in denser suburban settings.
Less commonly, a failing compressor, a stuck reversing valve, or a broken contactor can cause warm air output. These are more serious repairs and are usually accompanied by unusual noise, breaker trips, or a system that runs constantly without ever cooling the home.
What to Do Before You Call for Service
- Check and replace the air filter if it has not been changed in the last 60 to 90 days.
- Confirm the thermostat fan setting is on Auto, not On, so the coil gets time to drain condensation properly.
- Look at the outdoor unit for visible ice, debris buildup, or vegetation blocking airflow.
- If you see ice anywhere on the system, turn it off completely and let it thaw for several hours before running it again.
- Do not continue running a system that is blowing warm air. Continued operation on a low refrigerant charge or a frozen coil can damage the compressor, which is the most expensive component in the system to replace.
According to ENERGY STAR, regular filter changes and annual professional maintenance are the two most effective ways homeowners can prevent airflow related cooling failures before they start.
Why This Happens More in Peak Summer Heat
July puts more strain on a residential AC system than any other month. Systems run longer cycles, condensers work harder to shed heat into already hot outdoor air, and any marginal component or low refrigerant charge that survived spring gets pushed past its limit. A system that cooled adequately in May or June can start blowing warm air in July simply because the outdoor temperature and runtime demands have both increased.
For homeowners across New Holland, Earl Township, Leola, and Blue Ball who are dealing with warm air right now, same day diagnostic appointments are available through Shoemaker’s emergency HVAC service. Our team also services the surrounding Lancaster County communities as part of our expanded service area covering Chester County and eastern Lancaster County.
Full details on repair, replacement, and tune up services are available on our air conditioning services page.
Frequently Asked Questions
AC Blowing Warm Air in New Holland, PA
The most common causes are a dirty air filter restricting airflow, a low refrigerant charge from a leak, a dirty outdoor condenser coil that cannot release heat properly, or a frozen evaporator coil that is temporarily blocking cold air. A failing compressor is a less common but more serious possibility. Shoemaker can diagnose the exact cause on a single visit.
Yes. A clogged filter restricts airflow across the evaporator coil, which can cause the coil to freeze. Once ice builds up, cold air stops moving through the vents and the system may blow room temperature or warm air until the ice melts. Replacing the filter and letting the coil thaw resolves many of these calls without a service visit.
Signs include warm air from vents, hissing or bubbling sounds near the indoor unit, ice on the copper refrigerant lines, and longer cooling cycles that never quite reach the thermostat setting. Refrigerant does not get used up in a properly sealed system, so low levels almost always mean a leak that needs to be located and repaired, not just topped off.
No. Continuing to run a system that is low on refrigerant or has a frozen coil can damage the compressor, which is the most expensive component to replace. Switch the thermostat fan setting to Auto, turn the system off, and call for service. If the coil is frozen, give it several hours to thaw before a technician arrives.
Yes. Shoemaker Heating and Cooling serves New Holland, Earl Township, Leola, Blue Ball, and the surrounding Route 23 corridor in eastern Lancaster County, along with all of Chester County. Call (610) 671-3595 to schedule diagnostic service.