A diagnostic visit is where everything starts. When a technician arrives at a San Marcos home or commercial property, the first job is to understand what the system is actually doing, not just what the thermostat says. That means checking airflow, testing controls, inspecting the equipment, and tracing the problem to its source before any repair is proposed. Magnum Heating & A/C handles that process the same way on every call: look at the whole system, tell you what was found, and confirm the scope of work before anything is touched.
The visit covers what the system needs, not what is easiest to invoice. If the equipment is worth repairing, we repair it correctly. If it has reached the point where repair no longer makes sense, we say so and walk through the replacement options. Property owners, businesses, and anyone managing a rental in the area get the same straight answer either way.
Same-day service is often available for calls placed during our hours, every day from 9:00 AM to 9:00 PM. When a system is completely down, no cooling in the middle of a hot stretch or no heating when temperatures drop, those calls move to the front of the line. We take emergency HVAC calls across San Marcos and the surrounding area and work to get someone out the same day when same-day appointments are open.
Booking is handled on the phone. You call, we ask about the system and the situation, we confirm what is available, and we give you a price before anything is scheduled. If the property has a tenant or a business running inside it, let us know when you call. We work around occupied spaces and confirm what access is needed before the visit.
Affordable rates. Flexible timing. Reliable comfort.
A quote covers the work the diagnostic turns up. The things that move it are the fault itself, what has to be reached to fix it, the equipment involved, and whether a repair or a full replacement is the better path. A refrigerant leak that requires tracing and recovery is a different job from a blower motor swap or a ductwork seal. The quote reflects what the job actually is, not a flat rate applied before anyone has looked.
You get the price on the phone before anything is scheduled. If the scope changes once the technician is on site, that conversation happens before any additional work begins. Ask what the quote covers and you get a straight answer. The service page carries the full breakdown of what each type of job involves.
We protect your home. We service your system. We earn the call.
An old thermostat that reads the temperature wrong, cycles the system at the wrong time, or loses its settings after a power interruption is costing money on every run. A modern programmable or smart control gives you real visibility into what the system is doing and when, and it lets the equipment run on a schedule that matches how the building is actually used rather than running flat out whenever someone bumps the dial.
Replacing a thermostat is often worth doing on its own, separate from any repair or maintenance visit. We install and configure smart controls and standard programmable thermostats, and we confirm the new unit is communicating correctly with the system before we leave. If zoning is part of the picture, where different areas of the building need to behave independently, that conversation starts here too. Your system is in good hands with us.
If you are working out what the job needs, our guide to heating and cooling goes through it.
When some rooms are comfortable and others are not, or when the airflow at a vent is noticeably weaker than it should be, the cause is usually in the ductwork or the air handler rather than the equipment itself. We trace airflow problems back to the source, whether that is a collapsed duct section, a sealed-off return, or a blower that is not moving enough air through the system.
The compressor is the heart of a cooling system, and a condenser that is dirty, blocked, or failing puts real strain on it. We inspect, clean, and service condenser units, diagnose compressor problems, and assess whether the equipment is worth repairing or has reached the point where replacement is the more practical answer.
A seasonal tune-up before the cooling season and a heating check before temperatures drop are the two visits that prevent the most expensive calls. We check the furnace. We check the AC. We leave it running right. Maintenance covers inspection, cleaning, performance testing, and flagging anything that looks like it is heading toward a problem.
A system that runs continuously without bringing the temperature down is usually dealing with a refrigerant issue, a coil problem, or a restriction somewhere in the airflow path. We diagnose the actual cause rather than guessing, and we do not recommend a repair until we know what the system is actually doing.
Banging, rattling, squealing, and grinding each point toward different problems. A noise that was not there last week is worth a call, because the underlying cause tends to get worse the longer the system keeps running. We identify the source and address it before it becomes a larger failure.
Boilers heat a space by circulating hot water through radiators or radiant systems, and they need the same diagnostic attention as any other heating equipment. We service boilers, diagnose circulation and pressure problems, and repair or replace components that have failed. If a boiler is the primary heat source for a property, keeping it in good shape before the cold months arrive is the right move.
A repair call starts with a real diagnosis. The symptom, whether that is a system that will not turn on, one that runs but does not condition the air, or one that cycles on and off without doing much of either, is the starting point. The repair addresses what the diagnosis found, not what is easiest to reach. Code-compliant HVAC work on every job means the fix holds up, not just for the visit.
A system that is running fine still benefits from a scheduled inspection. Coils accumulate debris, filters restrict airflow, and small issues develop into larger ones between seasons. A maintenance visit on a working system is the most cost-effective call on the schedule, and it is the one most often skipped until something stops working. We handle residential maintenance for single-family homes and commercial maintenance for buildings where a failure is a business problem, not just a comfort one.
When a system has been repaired repeatedly, is running old, or is no longer able to hold the temperature it is set to, replacement is usually the more practical path. We assess the equipment, size the replacement correctly for the space, and handle the installation from start to finish. HVAC work sized and installed the way the manual calls for matters here more than anywhere else, because an undersized or oversized replacement creates new problems from day one.
The service page carries the full breakdown of what each job type covers. Call and we'll handle the furnace, the AC, and the ductwork.
We do. Properties outside the city limits and older homes on acreage are a regular part of what we cover in Hays County. Access is rarely the issue. What makes a rural property more involved is usually the equipment itself: systems that have not been serviced in years, units that are no longer manufactured, or ductwork that was added in stages without a plan behind it.
Older equipment is worth a look before assuming it needs to be replaced. Some of it runs well with maintenance and targeted repairs. Some of it has reached the point where parts are no longer available or the efficiency loss makes replacement the better answer. We make that call based on what we find, not on a general rule about age. If the property is outside the city and you are unsure whether we cover it, call and we will confirm.
We cover San Marcos and the communities around it throughout Hays County. That includes Redwood, Martindale, Kyle, Staples, and Uhland. Whether the property is inside the city or in the surrounding area, the same service applies: a real diagnostic, a price confirmed before anything is scheduled, and work performed by qualified HVAC technicians.
Local means we care what the neighbors think of our work, and that holds whether the call is a tune-up in San Marcos or a furnace repair on a rural property outside Martindale. If you are nearby and want to confirm we cover your address, call (830) 590-9782.
It can, depending on where the air handler, ductwork, or other components are located. When you call, let us know the layout of the property and where the equipment is installed. If attic or crawl space access is needed, we confirm that before the visit so the appointment is not delayed.
Often yes. When you call, we ask about the symptoms, how long they have been happening, and what the system was doing when the problem started. That conversation helps us understand what we are likely dealing with and come prepared. It does not replace the diagnostic, but it makes the visit more efficient.
Maintenance matters on newer equipment too. Manufacturers design HVAC systems to run within specific parameters, and regular tune-ups keep the equipment operating at those parameters. Skipping maintenance on a newer system can void warranty coverage and lead to problems that would not have developed otherwise.
Turn the system off and call us. A brief burning smell when the heat first comes on in fall can be dust burning off the heat exchanger, and it often clears on its own. A persistent burning smell, or one that appears unexpectedly, points to something that should be inspected before the system runs again.
Sometimes, and sometimes not. Adding a vent to a room requires the existing duct system to have enough capacity to support it. If the system is already undersized or the ducts are restricted, adding a vent can make the problem worse rather than better. We assess the duct system and the equipment before recommending a fix so the solution actually addresses the cause.
The regional climate puts a long cooling season on equipment, and humidity adds load on top of temperature during the warmer months. Systems that have been running hard through multiple summers often show wear at the condenser, the coil, or the refrigerant circuit first. When we diagnose a system in this area, we look at those components carefully alongside the controls and the ductwork to make sure the repair or replacement addresses what the equipment has actually been through.
It matters in the sense that it shapes what the technician prepares for, but it does not change whether we take the call. Older equipment may require a different approach to diagnosis and parts sourcing. Let us know the approximate age of the system when you call and we will factor that into the visit.
Yes. We cover San Marcos and the surrounding communities throughout Hays County, including Redwood, Martindale, Kyle, Staples, and Uhland. If your property is outside the city and you want to confirm coverage, call (830) 590-9782 and we will let you know.
A rattle usually means something is loose, whether that is a panel, a component inside the cabinet, or debris in the outdoor unit. A squeal most often points to a worn blower belt or a motor bearing that is starting to fail. Neither sound should be ignored, because the underlying cause tends to get worse the longer the system runs.
A system in a vacant property still benefits from a check before it is needed again. Equipment that has been sitting idle can develop issues that are not obvious until the system is asked to run. A pre-occupancy tune-up is a practical step before the property is used again, particularly after an extended vacancy.
The most useful thing a diagnostic visit does is answer that question honestly. Magnum Heating & A/C comes to the property, looks at what the system is actually doing, and tells you whether a repair makes sense or whether the equipment has run its course. Call (830) 590-9782 for a quote. We are available every day from 9:00 AM to 9:00 PM.
We also take work in: Canyon Lake, Seguin, Garden Ridge, Cibolo.
From a fast AC repair to a full system replacement, we handle the complete range of heating and cooling work for homes and businesses in San Marcos and across Hays County. The table below covers what each service includes, who it fits best, and a practical note to help you decide where to start. Call (830) 590-9782 for a quote on any of these services.
| Service Type | Scope of Work | Common Needs | Helpful Details |
|---|---|---|---|
| Furnace & AC System Replacement |
| Homeowners whose repair costs are stacking up or whose system can no longer hold the set temperature | South Texas summers accelerate wear on older equipment, making timely replacement a practical choice |
| Heating & Furnace Repair |
| Any home or building that loses heat during a cold snap | Even mild San Marcos winters can make a furnace failure urgent on the coldest nights |
| Seasonal Maintenance & Tune-Ups |
| Any homeowner who wants to prevent breakdowns before the next season arrives | A spring AC tune-up and a fall furnace check are the two visits that prevent the most expensive repairs |
| Indoor Air Quality & Air Filtration |
| Households concerned about dust, allergens, or airborne particles indoors | An air quality upgrade is straightforward to add when the system is already being serviced |
| Ductwork Repair & Sealing |
| Homes where the system runs constantly but comfort is uneven from room to room | Sealing the duct system often makes a bigger difference in comfort than replacing equipment |
| Heat Pump Repair & Service |
| Homes running a heat pump for both heating and cooling | Heat pumps are a common fit in South Texas and benefit from annual inspection of both modes |
| Whole-Home Dehumidification & Humidity Control |
| Hays County homes where high ambient humidity makes the indoor air feel uncomfortable even at the right temperature | Managing indoor humidity reduces extra load on the cooling system and improves overall comfort |
| Emergency HVAC Service |
| Any home or building where the HVAC system has stopped working and waiting is not an option | We take emergency calls every day from 9:00 AM to 9:00 PM and offer same-day service when available |
| AC Repair & Service |
| Homeowners and property managers whose AC stopped cooling or is underperforming | Same-day service is often available when the system goes down during peak summer heat |
| Thermostat & Smart-Control Installation |
| Anyone who wants better visibility and control over indoor temperature | A thermostat upgrade pairs well with ductwork improvements for room-by-room comfort control |
| Full System Installation & ReplacementMost Popular |
| Homeowners and commercial property owners replacing aging or failing equipment | We go over installation and replacement costs in plain terms before anything is scheduled |
| Heat Pump Installation |
| Homeowners replacing an older system or adding comfort to a new space in a mild-winter climate | San Marcos winters are mild enough that a heat pump handles both seasons efficiently from a single system |
Call (830) 590-9782 to talk through your system, get a straight answer on what it needs, and schedule service at a time that works for you.
(830) 590-9782