It is the middle of July in Londonderry, the outdoor thermometer reads 91 degrees, and the air conditioner that ran without complaint last summer now blows warm air through every vent. The compressor hums, the thermostat calls for cooling, yet the house keeps warming. This is one of the most common calls we receive, and it usually points to a specific, diagnosable problem rather than a total system failure. At Paradigm Plumbing, AC repair is a process of methodical elimination, tracing the fault from symptom to root cause and correcting it so your home returns to comfort quickly.
Air conditioning is not a luxury during a New Hampshire heat wave. Elderly residents, infants, and anyone with respiratory conditions depend on stable indoor temperatures. When a system quits, the response time and the accuracy of the diagnosis both matter. We approach every repair with the understanding that a cooling failure is disruptive, and we bring the tools, refrigerant certifications, and experience needed to resolve the issue in a single visit whenever the parts are available.
How We Diagnose a Failing Air Conditioner
A proper diagnosis starts with the measurements, not with guesswork. When our technician arrives, the first step is to confirm the reported symptom and observe the system through a full cooling cycle. We check the thermostat setting, the state of the air filter, and the condition of the electrical disconnect at the outdoor unit. Many “no cooling” calls trace back to something as simple as a tripped breaker, a clogged filter that has frozen the evaporator coil, or a thermostat that has lost its settings after a power interruption.
Once the obvious causes are ruled out, we move to the refrigerant circuit and the electrical components. Using manifold gauges, we read the high-side and low-side pressures and compare them against the manufacturer’s target values for the measured outdoor temperature. Pressure readings tell us whether the system is low on refrigerant, whether the metering device is restricted, or whether the compressor is failing to pump correctly. We also measure the temperature split between the return air and the supply air, which for a healthy system typically falls between 16 and 22 degrees. A split outside that range points directly toward a specific fault.
The Most Common AC Repairs in Londonderry Homes
Over years of servicing cooling systems across the region, certain failures appear far more often than others. Understanding these helps homeowners recognize warning signs before a small problem becomes a major expense.
- Low refrigerant from a leak: Refrigerant does not get consumed. If a system is low, there is a leak somewhere in the coil, line set, or fittings. We locate the leak with electronic detectors or nitrogen pressure testing, repair it, evacuate the system to remove moisture and air, then recharge to the exact factory specification by weight.
- Failed capacitors: The start and run capacitors give the compressor and fan motors the electrical boost they need to begin turning. Heat and age cause them to weaken. A bulging or out-of-spec capacitor is one of the most frequent causes of a unit that hums but will not start.
- Contactor and relay problems: The contactor is the electrical switch that sends power to the outdoor unit. Pitted or stuck contacts interrupt cooling or cause the unit to short cycle.
- Frozen evaporator coil: Restricted airflow or low refrigerant causes the indoor coil to ice over. The system then stops cooling entirely. We identify why the freeze occurred rather than simply thawing it.
- Failing compressor: The compressor is the heart of the system. When it draws excessive amperage, fails to build pressure, or trips its internal overload, we assess whether a repair or a full replacement is the better long-term choice for you.
Each of these failures produces its own signature in the pressure readings, amperage draw, and temperature measurements. Because we gather that data before opening the wallet, we avoid the common trap of replacing parts on speculation. When Paradigm Plumbing quotes a repair, it is because the data supports it.
Scenario: The Older System That Struggles Every August
Some Londonderry homes have central air units that are 12 to 18 years old. These systems often still run, but they cool weakly and drive up electric bills. In this scenario, our repair work focuses on restoring efficiency: cleaning a caked condenser coil, replacing a tired capacitor, straightening bent fins that block airflow, and topping off refrigerant after sealing a slow leak. We also discuss honestly whether continued repairs make financial sense. A unit using the older R-22 refrigerant faces steep material costs because that refrigerant is no longer produced, and in these cases we lay out the numbers so you can make an informed decision.
The goal is never to push a replacement. Many older units have years of service left once a single failed component is addressed. Our role is to give you accurate information and a repair that lasts, not a temporary patch that fails again during the next heat wave.
Scenario: The Sudden Complete Shutdown
Another frequent call is the system that worked perfectly one hour and then died completely. These failures usually trace to electrical faults: a failed capacitor, a blown low-voltage fuse on the control board, a tripped float switch in a clogged condensate drain, or a contactor that has stopped closing. We carry the common electrical components on our trucks so that these repairs can be completed on the spot. A clogged condensate line, for example, triggers a safety switch that shuts the system down to prevent water damage. Clearing the line and confirming proper drainage restores cooling within the same visit.
Why Experience Matters in AC Repair
Air conditioning repair combines electrical work, refrigerant handling, and airflow science. A technician must read pressures correctly, understand superheat and subcooling, handle refrigerant under EPA regulations, and troubleshoot control circuits safely. Cutting corners on any of these creates safety hazards or short-lived repairs.
Paradigm Plumbing was founded in 2006 by Stephen (“Steve”) Labbe, who brings over 26 years of experience in the plumbing, heating, and air conditioning industry. That depth of experience shapes how every repair is performed. Our motto, “Experience the Paradigm Shift,” reflects our commitment to changing the way homeowners think about what a plumbing, heating, or air conditioning contractor should be: a company that delivers the highest quality workmanship together with genuine, responsive customer service.
We provide AC repair alongside our full range of services including HVAC installation, furnace service, heating repair, and plumbing throughout Londonderry and the surrounding communities of Hooksett, Manchester, Concord, Suncook, Pembroke, and Bedford, NH. When you call us for a cooling failure, you reach a company that treats your comfort and your home with the care it deserves.
What to Expect When You Call for AC Repair
From the first phone call, our aim is a clear, honest, and efficient service experience. Here is how a typical repair visit unfolds:
- Scheduling and arrival: We gather the details of your problem and dispatch a technician equipped for the most likely repairs.
- Full system inspection: We test the thermostat, filter, electrical connections, refrigerant pressures, and airflow before reaching any conclusion.
- Clear explanation: We show you what we found and explain the repair options in plain language, without pressure.
- Repair and verification: We complete the work, then run the system through a full cooling cycle to confirm the fault is resolved and the temperature split is correct.
- Recommendations: We point out any developing issues so you can plan ahead and avoid future breakdowns.
When the temperature climbs and your air conditioner stops keeping up, reach out to Paradigm Plumbing We restore comfort to Londonderry homes with accurate diagnostics, lasting repairs, and the level of service that has defined our work since 2006.
