A geothermal system that loses heating or cooling efficiency, cycles on and off constantly, or stops working entirely requires specialized diagnostic knowledge. Geothermal systems operate on principles different from conventional furnaces or air conditioners—they involve ground loop pressures, refrigerant circuits, and heat exchanger performance that most technicians don’t understand well enough to diagnose accurately.
J&G Heating & Air Conditioning specializes in geothermal system repair. Our factory-trained technicians hold NATE certification in heat pump operation and understand ground-source heat pump diagnostics from refrigerant charge to ground loop integrity. We use professional test equipment to pinpoint problems accurately—eliminating guesswork and unnecessary parts replacement.
When you’re dealing with a geothermal system that’s not heating or cooling properly, the contractor matters as much as the equipment. Our experience, manufacturer certifications, and specialized diagnostic equipment all add up to one thing: accurate diagnosis and effective repair the first time, backed by people who understand ground-source heat pump technology.
J&G Heating & Air Conditioning provides expert geothermal repair across all of Lancaster County. Our factory-trained technicians bring specialized diagnostic knowledge and proper test equipment to every service call. Whether your system needs simple thermostat replacement or complex compressor diagnosis, we deliver accurate diagnosis and professional repair.
Geothermal systems are reliable, but when problems develop, they require specialized diagnosis. Here are the most common warning signs that indicate your system needs professional attention.
Your thermostat is calling for heating or cooling, but the system produces little to no temperature change. Causes include: low refrigerant charge (most common), a stuck compressor valve, ground loop circulation failure, or thermostat not signaling the compressor. A ground loop leak slowly losing refrigerant is a common culprit in older systems.
The compressor runs for 5–10 minutes, then shuts off and repeats constantly instead of running steadily for 20–30 minutes. Short-cycling causes temperature swings and wastes energy. Causes include: refrigerant overcharge, air in the refrigerant line, thermostat calibration drift, or compressor reaching unsafe pressure.
Hissing signals refrigerant escaping a leak. Gurgling means air trapped in the refrigerant or ground loop circuit. Grinding suggests compressor bearing wear or internal damage. These noises indicate problems worsening if ignored. We pressure-test all connections to locate leaks and test compressor operation to assess bearing condition.
The compressor runs but the ground loop isn’t circulating heat transfer fluid properly. You notice this if heating/cooling output is weak despite normal compressor operation. Causes include: ground loop clogged with ice (in winter), pump failure, or internal blockage in the loop. We measure ground loop pressure and flow to diagnose circulation problems.
You adjust the thermostat but the compressor doesn’t respond, or it cycles without respecting the setpoint. Causes include: thermostat wiring broken, thermostat miscalibrated, or control board failure. We test thermostat signals using a multimeter to confirm the thermostat is actually sending command signals to the compressor.
Water pooling around the indoor equipment signals a blocked condensate drain (in cooling mode) or a refrigerant leak that’s leaking into the condensate pan. A blocked drain is minor—we clear it. A refrigerant leak requires pressure-testing to locate the leak site and brazing to seal it.
Every geothermal repair we do follows the same proven diagnostic process — designed to identify the root cause accurately and deliver a repair that actually solves the problem. Tap any step below to see exactly what happens.
You describe what’s happening: “The heat pump won’t heat despite the thermostat calling for it” or “The system cools fine but heating output is weak.” We ask clarifying questions: “When did this start?” “Have you noticed any sounds?” “Has the system been worked on recently?” We also review your system’s maintenance history—previous repairs, any work done, and parts replaced—to understand what problems may have developed before.
This conversation informs our testing strategy—we’ll focus diagnostic tests on the most likely causes based on your symptoms and history.
We observe your system: external equipment condition, evidence of leaks or corrosion, piping routing, and overall system appearance. We check the thermostat—verifying it’s set to the right mode and setpoint. We also listen while the compressor runs: normal operation is a steady hum; grinding or squealing indicates mechanical problems.
We connect manifold gauges to the system’s service ports—measuring high-side pressure (compressor discharge) and low-side pressure (compressor inlet). These pressures tell us whether refrigerant charge is correct, too low, or too high. For heating mode: normal pressures depend on outdoor ground temperature and system capacity, but specific values guide our assessment. For cooling mode: similar pressure patterns reveal charge status. If pressures are abnormal, we measure superheat (temperature above saturation point)—the gold standard for confirming refrigerant charge accuracy.
We measure ground loop pressure and flow using a specialized testing port (if equipped). Low pressure indicates a circulation problem—pump failure or blockage. We also measure temperature at the ground loop inlet and outlet; temperature difference indicates whether heat transfer is occurring or if circulation is blocked. If ground loop flow is poor or pressure is low, we evaluate whether the problem is pump failure, internal loop blockage, or ice formation (in winter). This testing is critical—many geothermal problems originate in the ground loop, not the compressor.
We measure compressor discharge temperature—how hot the refrigerant leaves the compressor. High discharge temperature indicates excessive compression (possibly refrigerant overcharge) or high ground loop temperature (in summer). Low discharge temperature suggests insufficient compression (possibly low refrigerant charge) or failing compressor. We also measure compressor electrical current draw during startup and steady-state operation. High current draw suggests mechanical stress; low draw suggests compressor not operating at full capacity.
We test the thermostat control signal—using a multimeter to verify that when the thermostat calls for heating or cooling, a 24-volt signal reaches the compressor control board. If no signal is present, the thermostat or control wiring is broken. If the signal is present but the compressor doesn’t respond, the control board may be failing. We also verify that all safety controls—high-pressure switch, low-pressure switch, thermal overload—are responding correctly.
Once we’ve diagnosed the problem, we perform the repair: Refrigerant leak: locate with UV dye or electronic leak detector, braze the leak, evacuate the system, and recharge. Low refrigerant charge: add the correct amount of refrigerant matched to manufacturer specifications. Ground loop circulation failure: replace pump, clear blockage, or address freeze (thaw and add freeze protection). Compressor failure: replace compressor (major repair, but necessary for system recovery). Control board failure: replace board and reprogram control settings. Thermostat failure: replace thermostat and verify new unit communicates with compressor.
After repair, the system is restarted and monitored: pressures are verified normal, temperatures at all points are measured, and the system is allowed to run through complete heating and cooling cycles to confirm reliable operation.
After repair, pressures are verified returning to normal, temperatures are measured at all critical points, and the system is cycled through heating and cooling to confirm reliable operation. We document all test results and explain what we found, what we repaired, and what the repair involved. You receive a service report with: repair description, parts replaced, labor time, warranty terms (parts and labor), and explanation of what failed and why. We also provide our emergency contact number for questions during the first days of operation.
Our technicians are experienced in all types of geothermal system repairs, from simple thermostat issues to complex compressor replacement. Here are the most common repairs we perform.
A slow refrigerant leak reduces cooling capacity gradually. We locate the leak using UV dye (UV light reveals dye-marked refrigerant) or electronic leak detectors. Once located, we braze the connection, evacuate the system, and recharge. Typical repair time: 2–3 hours.
Schedule Refrigerant RepairThe circulator pump moves heat transfer fluid through the ground loop. A failed pump stops circulation, making the system unable to exchange heat efficiently. Replacement usually takes 1–2 hours and immediately restores performance.
Get Ground Loop Pump ServiceThe compressor is the system’s heart. A failed compressor means the system cannot cool or heat. Compressor replacement is the most involved repair (4–6 hours) and one of the most expensive. We only recommend replacement when the compressor has genuinely failed, not as a preventive measure.
Schedule Compressor ReplacementA leak in buried ground loop piping causes gradual refrigerant loss and pressure drop. We pressure-test the loop to locate the leak, then repair using specialized procedures. Depending on the leak’s location and severity, repair time varies from 2–4 hours.
Get Ground Loop Leak ServiceModern geothermal systems use sophisticated control boards managing compressor operation, safety interlocks, and thermostat communication. A failed board stops the entire system. Replacement and reprogramming typically take 1–2 hours.
Schedule Control Board ServiceIf the thermostat isn’t communicating with the compressor or isn’t reading room temperature accurately, replacement may be necessary. New smart thermostats offer energy savings benefits and remote control capabilities. Replacement and programming typically take 30–45 minutes.
Get Thermostat Service
We believe every homeowner in Lancaster County deserves access to reliable heating and cooling — regardless of budget. That’s why J&G Heating & Air Conditioning partners with trusted financing providers to offer flexible payment plans that fit your financial situation. Whether you’re replacing an aging boiler, upgrading to a high-efficiency air conditioning system, installing a high-efficiency heat pump, or investing in a new generator system, financing allows you to enjoy the comfort you need today while spreading payments over time.
Our team will walk you through every available option during your free estimate, helping you understand monthly payment amounts, interest rates, and approval requirements. We want the financial side of your project to feel just as comfortable as the temperature in your home.
As an authorized Wells Fargo financing partner, J&G Heating & Air Conditioning offers a range of credit options to help you manage the cost of your new heating or cooling system. With competitive rates and flexible terms, qualifying homeowners can enjoy convenient monthly payments that fit comfortably into their household budget.
Apply Now
Through our partnership with PowerPay, we provide another trusted financing pathway for Lancaster County homeowners ready to upgrade their home comfort. PowerPay’s streamlined application process and flexible repayment plans make it easy to get started on your project without delay.
Apply Now
GoodLeap offers flexible financing options and competitive rates, making it easy for homeowners to invest in high-efficiency heating, cooling, and generator systems. With a simple application process and a variety of repayment terms, upgrading your home comfort doesn’t have to mean a large upfront cost.
Apply Now
When you join one of our maintenance programs, you’ll receive scheduled tune-ups performed by our NATE-certified technicians who know your system inside and out. We’ll clean critical components, check refrigerant levels, inspect electrical connections, test safety controls, and ensure everything is operating as it should.
Regular maintenance doesn’t just prevent breakdowns — it also helps lower your energy bills and protects your manufacturer warranty coverage. It’s one of the smartest investments you can make in your home’s comfort and your family’s safety.
Geothermal systems are durable, but when problems develop, accurate diagnosis is essential. Misdiagnosis by technicians unfamiliar with ground-source heat pumps leads to wasted money on unnecessary parts. J&G Heating & Air Conditioning brings factory-trained expertise and proper diagnostic equipment to every geothermal repair—ensuring the problem is identified correctly and the repair actually solves it.
Our technical expertise prevents expensive guessing. We test refrigerant pressures, ground loop circulation, compressor operation, and control system communication—using objective measurements to pinpoint problems. That precision prevents recommending expensive parts you don’t actually need.
Annual tune-ups catch small problems early before they become expensive repairs.
Geothermal MaintenanceIf your system is aging, upgrade to newer technology with improved efficiency.
Geothermal InstallationIf you have a conventional AC unit complementing your heating system, we service that too.
AC Repair ServicesMajor repairs can be spread across monthly payments with approved credit.
Explore Financing
© Red Barn Media Group 2026