How to Troubleshoot Common HVAC Issues Before Calling a Professional in Delaware County

Quick Answer for Homeowners: Before calling an HVAC technician in Delaware County or the greater Philadelphia area, check these basics: replace a dirty air filter, reset a tripped circuit breaker, verify your thermostat settings, clear blocked vents, and inspect the condensate drain for clogs. Most HVAC no-heat or no-cool calls are resolved at this first-check level. If these steps don’t restore normal operation, the issue is likely mechanical,  refrigerant, electrical, or a failing component, and you’ll need a licensed professional.

Your heat stops working at 11 PM on a January night in Havertown. Or your AC refuses to cool in the middle of an August heat wave that’s pushing the feels-like temperature past 100°F. Before you panic and call anyone, there are a handful of things you can check yourself in about 15 minutes that might save you a service call entirely, or at least give a technician accurate information when you do call.

This guide walks through the most common HVAC problems that come up in Delaware County homes, what causes them, what you can safely check yourself, and where the line is between DIY and “please send a pro.”

Start Here: The Checks That Solve 40% of HVAC Calls

It sounds almost too simple, but the four most common reasons an HVAC system seems broken are things you can fix yourself in minutes.

The first is the air filter. A clogged filter doesn’t just reduce airflow; it can cause the evaporator coil to freeze solid, make the system overheat and shut itself off, or spike your energy bill by 15% or more. Check your filter. If it’s gray and you can’t see the filter material anymore, replace it. Standard 1-inch filters should be swapped every one to three months, more often if you have pets or anyone in the home with allergies.

The second is the circuit breaker. HVAC systems draw significant amperage, especially at startup. A momentary power surge can trip the breaker without any other damage occurring. Go to your electrical panel, look for a tripped breaker (it’ll be in the middle position rather than fully “on”), and reset it. Also check the disconnect switch on the wall next to your outdoor unit; it sometimes gets accidentally switched off.

The third is the thermostat itself. Confirm it’s in the right mode (heat or cool), that the fan is set to “auto” rather than “on,” and that the temperature setpoint actually calls for conditioning. A thermostat set to 68°F in a 70°F house isn’t going to do anything. If you have a smart thermostat, check the app, sometimes schedules or vacation modes get activated accidentally.

The fourth is vents and registers. Walk through every room and make sure supply and return vents are open and unobstructed by furniture, rugs, or curtains. Closing too many vents actually increases system pressure, which can cause its own set of problems.

Your AC Is Running But Not Cooling

This is one of the most common calls during a Philadelphia-area summer, and there are a few distinct causes.

If airflow feels weak at the registers, go back to the filter first. Restricted airflow is the leading culprit. After that, check whether the indoor air handler’s access panel is fully closed. Most systems have a safety switch that cuts the unit off if the panel is open or not seated properly.

If airflow seems fine but the air coming out just isn’t cold, look at the outdoor condenser unit. Is it running? You should hear the fan spinning and the compressor humming. If the outdoor unit is off while the indoor air handler is running, you likely have an electrical issue: a failed capacitor, a tripped high-pressure switch, or a wiring problem.

Also, look at the refrigerant lines running into the outdoor unit. If you see ice forming on the copper lines or on the indoor coil, the system is either low on refrigerant or has a serious airflow restriction. Turn the system off immediately and let it thaw. Running the system with a frozen coil can burn out the compressor, which is an expensive failure. After thawing (this can take a few hours), replace the filter and try again. If it freezes again, you have a refrigerant leak that needs professional attention. Refrigerant handling requires an EPA Section 608 certification and is not a DIY repair.

One more thing worth doing: gently rinse the exterior of the condenser unit with a garden hose. Grass clippings, cottonwood seeds, and debris build up on the condenser coils overthe summer and reduce the unit’s ability to expel heat. Don’t use a pressure washer; you’ll bend the fins. A regular hose does the job.

Your Furnace or Heat Pump Won’t Heat

For gas furnaces, start by checking whether the system is attempting to ignite. Most modern furnaces have an electronic igniter, a small glow plug you can often see through the sight glass on the front of the furnace. If it glows orange but the gas doesn’t ignite, or if the furnace tries three times and then locks out, there’s a mechanical issue that needs a tech. Look for a flashing LED error code on the control board. Many furnaces display a blink pattern that directly corresponds to a diagnostic code in the owner’s manual.

Check the gas valve is open (the handle should be parallel with the gas line, not perpendicular). If other gas appliances in your home are working, gas supply isn’t the problem.

For heat pumps specifically, remember that they work differently than furnaces. When outdoor temperatures in Delaware County drop below about 35-40°F, a heat pump’s efficiency drops and the backup electric heat strips should kick in. If your home is cold and you don’t see an “auxiliary heat” or “emergency heat” light on the thermostat, the backup heating element or the board that controls it may have failed. This is definitely a call for a technician.

If you have a boiler system, check the pressure gauge. Most residential boilers should operate between 12 and 25 PSI. Very low pressure can prevent the system from circulating hot water to the radiators or baseboard heaters. Some boilers have an auto-fill valve; others need to be manually filled. Your owner’s manual will tell you how to do this safely.

If you live in Delaware County and your system isn’t responding to any of these checks, the team at Boyle Energy is a solid first call. They’ve been handling heating and air conditioning repair in this area since 1937 and offer service plans that can prioritize your call. Reach them at 610-897-7580. It’s worth calling early in the season before the backlog builds.

Diagnosing Strange Noises

HVAC systems talk to you, and once you know the language, the sounds are actually useful.

Banging or clanging when the system starts or runs usually means something mechanical is loose inside a blower wheel that’s come off balance, a loose panel, or in worst cases, something breaking apart inside the compressor. Turn the system off and call a tech.

Squealing is almost always a belt or a bearing. Older systems use a belt-driven blower; newer ones use direct-drive motors with bearings. Either way, squealing means friction and wear, it won’t get better on its own.

Clicking repeatedly at startup without the system coming on usually points to a failed capacitor on the outdoor unit. Capacitors are the component that gives the compressor and fan motor the electrical “jolt” to start. They commonly fail in older systems and are a relatively straightforward replacement for a technician.

Rattling that only happens for the first minute after startup is often just the metal ductwork expanding as warm air passes through it, that’s normal. Rattling that continues is worth investigating, typically a loose panel, screw, or debris inside the system.

Water Leaking From Your Indoor Unit

If you see water pooling around your air handler or furnace, the condensate drain is almost certainly clogged. As your AC runs, it pulls moisture from the air that moisture drips into a drain pan and flows out through a plastic condensate line. Algae and mold love this damp environment, and the line can clog completely within a season.

Most systems have a float switch in the drain pan that shuts the system off when the pan fills with water (this is why your AC suddenly “stops working” on a humid day). Locate the end of the condensate drain line, it usually exits through a wall or into a floor drain and check whether it’s draining freely. You can try using a wet/dry shop vac to suction the clog out from the drain end.

To prevent this from happening monthly, pour a diluted white vinegar solution (about one cup) into the condensate line access point on the air handler. It kills algae without damaging the PVC piping.

Short Cycling: When Your System Keeps Turning On and Off

If your system runs for two or three minutes, shuts off, and then starts again repeatedly, that’s called short cycling. It’s hard on compressors and dramatically increases wear. Common causes include a dirty filter restricting airflow (start there), a refrigerant leak causing the low-pressure safety switch to trip, an oversized system that cools the space too quickly before proper dehumidification occurs, or a failing thermostat that’s giving false temperature readings.

Short cycling isn’t something to ignore. Each startup cycle draws the most electrical current and puts the most stress on the compressor. If changing the filter doesn’t resolve it, have the system inspected.

Uneven Temperatures Room to Room

Delaware County homes, particularly older ones in neighborhoods like Havertown, Drexel Hill, and Springfield, often have ductwork that was sized for a different era of equipment. Uneven temperatures are rarely about the equipment itself, they’re usually a distribution problem.

Check that all supply registers are open. Look for flex duct that may have become kinked or disconnected in the attic or crawlspace. According to the U.S. Department of Energy, duct leakage accounts for 20 to 30% of conditioned air loss in a typical home which is a significant amount of wasted energy and comfort.

Zoning, duct sealing, and properly sizing the system to the home’s actual load are the longer-term solutions. A Manual J load calculation (the industry standard sizing method) can confirm whether your equipment is the right size for your space.

When to Stop Troubleshooting and Call a Professional

Some things are genuinely not safe to DIY. If you smell gas, leave the house and call your gas company and 911 do not attempt to locate the leak yourself. If your carbon monoxide detector goes off, evacuate immediately. A cracked heat exchanger on a gas furnace can leak CO into your living space without any visible sign, and it’s only detectable with professional equipment.

Low refrigerant, electrical failures, heat exchanger cracks, compressor issues, and anything involving gas line connections require a licensed technician. Trying to handle these yourself risks serious injury, equipment damage, or voiding your manufacturer warranty.

As a locally trusted Havertown HVAC and energy services company, Boyle Energy provides full diagnostic and repair services across Delaware County, Chester County, Montgomery County, and Philadelphia. Our technicians carry certifications in heat pump service, boiler systems, gas codes, air conditioning, and low-voltage troubleshooting, so they’re equipped for whatever your system throws at them. You can call us at 610-897-7580. If you want to stop reacting to breakdowns and get ahead of them, ask about their annual maintenance plan. It’s the most cost-effective thing you can do for a home HVAC system.

One Last Word on Maintenance

Being a reliable hvac company in Philadelphia and the surrounding suburbs means Boyle Energy hears the same story often: a homeowner skips annual tune-ups for three or four years, and then faces a $3,000 compressor replacement that a $150 annual inspection might have prevented. Annual service visits catch failing capacitors, refrigerant that’s slightly low, dirty coils, and loose electrical connections before they cascade into larger failures. Industry data consistently shows that regularly maintained HVAC systems last 25 to 40% longer than neglected ones. That math tends to be persuasive.

FAQ Section

Q1: Why is my AC running but not cooling my house in Delaware County?
The most likely causes are a dirty air filter restricting airflow, a frozen evaporator coil, a failed outdoor capacitor preventing the compressor from starting, or low refrigerant. Start by replacing the filter and checking whether the outdoor unit is actually running. If the outdoor unit is off while the indoor fan runs, you likely have an electrical component failure that needs a technician.

Q2: How do I reset my HVAC system when it stops working?
Turn the thermostat completely off, go to your electrical panel and reset any tripped breaker for the HVAC system, wait 30 seconds, and then turn the thermostat back on. Also check the disconnect switch near the outdoor unit. If the system trips the breaker again after reset, do not reset it a third time, a repeatedly tripping breaker indicates an electrical fault that needs professional diagnosis.

Q3: Why does my furnace keep turning on and off every few minutes?
This is called short cycling. The most common causes are a clogged air filter, a refrigerant issue tripping a safety switch, or a thermostat malfunction. Replace the filter first. If it continues, the system needs professional inspection short cycling causes premature compressor failure if left unaddressed.

Q4: Why is water leaking from my air conditioner inside the house?
The condensate drain line is almost certainly clogged. Your AC removes humidity from the air, and that water needs to drain out through a plastic line. When the line clogs, the drain pan fills and water overflows. Many systems have a float switch that shuts the unit off when this happens. Clear the clog using a wet/dry vac at the drain outlet, then prevent recurrence by pouring diluted white vinegar into the drain access point monthly.

Q5: How often should I replace my HVAC air filter in the Philadelphia area?
For standard 1-inch filters, every one to three months. If you have pets, young children, or anyone with allergies or asthma, replace it closer to every month. Higher-MERV filters (3-inch and 4-inch media filters) can last up to six to twelve months but check the manufacturer’s recommendation. A dirty filter is the leading cause of preventable HVAC breakdowns.

Q6: Why is my heat pump not heating when it’s really cold outside?
Heat pumps lose efficiency when outdoor temperatures fall below about 35 to 40°F, which happens regularly in Delaware County winters. When that happens, the backup electric heat strips should engage. If your home stays cold and no “auxiliary heat” or “emergency heat” light appears on the thermostat, the backup heating element or its control board may have failed. This requires a technician.

Q7: Is it normal for my HVAC system to make a banging noise at startup?
A brief click or thud as the system starts is normal duct expansion. Loud banging or clanging is not normal, it typically indicates a loose or broken component inside the blower assembly or, more seriously, inside the compressor. Turn the system off and call a technician. Running a system with a broken internal component can rapidly escalate into a total system failure.

Q8: How do I know if my HVAC system needs a tune-up or a full replacement?
A general industry guideline is the “$5,000 rule”: multiply the system’s age in years by the estimated repair cost. If that number exceeds $5,000, replacement is often the better financial decision. Systems over 15 years old that require repairs costing more than 50% of replacement value are also strong candidates for replacement. A qualified technician can assess the system and give you an unbiased recommendation. Boyle Energy is known specifically for this kind of honest evaluation.