When a system stops working, the first question is not which brand made it or how old it is. The first question is who can get here and what it is going to cost. Magnum Heating & A/C covers Seguin and the surrounding area for the full range of heating and cooling work, from a furnace that will not light on a cold morning to a central air system that has been running warm all week. We handle the diagnosis, the repair, the seasonal maintenance, and the full replacement when the equipment has reached the end of its useful life. Call (830) 590-9782 for a quote, and we confirm the price before anything is scheduled.
Seguin is a city with a real mix of properties: older homes where the original equipment has been running for years, newer construction where the system is young but may never have been tuned to the space it serves, and commercial buildings where a breakdown is not just an inconvenience but a problem for the people inside. We work across all of it. Whatever the property is doing, a single call is the place to start.
A tune-up is not just a box to check. When a qualified technician works through a seasonal maintenance visit, they are looking at the parts of the system that carry the most load and are most likely to give out at the worst time. On the cooling side, that means checking refrigerant levels, cleaning coils, testing the blower and air handler, and confirming that the controls are reading and responding correctly. On the heating side, it means inspecting the heat exchanger, testing ignition, and making sure the system is moving heat the way it was designed to.
The point of doing this before the season peaks is straightforward. A problem caught in spring costs less to fix than a compressor that gives out in the middle of a stretch of heavy summer heat. A furnace that is running slightly off is easy to correct in fall. The same furnace, failing in January, is an emergency. We check the furnace. We check the AC. We leave it running right.
Maintenance visits also give us a clear picture of what the system is actually doing versus what it should be doing, which matters when you are trying to decide whether to repair aging equipment or plan for a replacement. That conversation is easier when you have current information rather than a guess.
Pricing for HVAC work is not a flat number, because no two jobs are the same. What the fault turns out to be, what has to be accessed to reach it, and whether a repair is the right answer or a replacement makes more sense are the things that move a quote. A straightforward repair on an accessible component is a different scope from a refrigerant leak that has to be located and sealed before the system can be recharged. A tune-up on a system that has been maintained regularly is a different job from one that has not been serviced in years.
When you call, we ask about the property and what the system is doing. From there we give you a clear rate before we schedule anything. You know what the visit covers and what the work will cost before anyone comes out. If the scope changes once the technician is on site, that conversation happens before any additional work is done. Code-compliant HVAC work on every job is part of how we operate, and that includes being straightforward about what the job involves.
Energy-efficiency upgrades, system replacements, and equipment installations all carry their own variables: the size of the space, the condition of the existing ductwork, and whether the building's layout creates any access challenges. The service page carries the full breakdown of what each type of job involves. We're one phone call from getting your comfort right.
Seguin has the kind of housing mix where one call is genuinely not like the next. An older home that has been on the same equipment for a long time presents a different set of questions than a newer build where the system is still under its original configuration. Commercial properties add another layer, because a breakdown during business hours carries a cost beyond the repair itself.
When a system stops working or starts behaving differently, the first job is finding out why. That means testing the controls, checking refrigerant levels, inspecting the condenser and compressor, and working through the components most likely to be causing the reported symptoms. A refrigerant leak diagnosis, for example, is not just a matter of adding refrigerant. The leak has to be found and addressed or the problem returns. We do not patch around a cause.
For a system that is running but has not been serviced recently, a maintenance visit is the right starting point. Air handler and blower service, coil cleaning, and control calibration all contribute to how efficiently the system runs and how long it lasts. We treat your home and its system the way we would our own, which means we look at the whole picture rather than just the part that was called out.
When repair costs are stacking up or the system is no longer holding the temperature it is supposed to, replacement is usually the more practical answer. 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 means the new system actually performs the way it should, rather than running constantly because it was undersized or short-cycling because it was oversized. The service page carries the full scope of what a replacement involves.
Rooms that never quite reach the set temperature, or that feel warmer or colder than the rest of the house, are one of the most common complaints we hear. The cause is not always the equipment itself. Leaky or undersized ductwork is frequently behind it, letting conditioned air escape before it reaches the rooms it is supposed to serve. A pressure imbalance in the duct system can push air toward some rooms and starve others.
In some cases the issue is a mini-split or ductless system that was added without being properly integrated into the overall comfort plan for the space. In others it is a thermostat that is not reading the space accurately or controls that are not communicating with the air handler correctly. We trace these problems back to the source rather than adjusting the thermostat and hoping it evens out. Ductwork repair and sealing, humidifier and dehumidifier installation, and zoning upgrades all come into play depending on what the diagnosis turns up.
Humidity is its own factor in this region. When indoor humidity is too high, the air feels heavier than the thermostat reading suggests, and the system works harder to compensate. A whole-home dehumidifier integrated with the existing HVAC equipment addresses that directly, rather than leaving the air conditioner to carry the full load.
Same-day service is often available, and for a property with no heating or no cooling at all, we treat it as the priority it is. A home without a working system is not a situation to leave until next week. We are available every day from 9:00 AM to 9:00 PM, and emergency calls are moved to the front of the line when appointments allow.
For tenants, businesses, and rental properties where the building has to stay occupied and operational, we work around the schedule as much as possible. When you call, tell us what the situation is and we will confirm what is available. We do not make promises about arrival windows, but we give you a clear picture of what to expect before the call ends. Affordable rates. Flexible timing. Reliable comfort.
If you would rather read than call, the page about heating and cooling has the detail.
A system that starts making a noise it was not making before is telling you something. Banging or clanking usually points to something loose or broken inside the air handler or compressor cabinet. Squealing often comes from a blower motor or belt that is wearing out. Rattling can mean a panel has come loose or debris has gotten into the outdoor unit. Any of these is worth a service call, because the underlying cause tends to get worse the longer the system keeps running.
Standing water near the air handler or the indoor unit of a mini-split usually points to a blocked or disconnected condensate drain. When the drain line cannot clear, the overflow pan fills and water ends up on the floor. Left unaddressed, it can cause water damage and create conditions inside the unit that affect air quality. We clear the drain, confirm the condensate line is routed correctly, and check whether anything else contributed to the backup.
These are the components that tell the system when to start, when to run, and when to stop. A failing capacitor is one of the more common reasons an AC unit will not start or will start and then cut out quickly. A worn contactor affects how power reaches the compressor and the condenser fan. A control board fault can produce symptoms that look like several different problems at once. We test these components as part of a full diagnostic rather than replacing parts without confirming the cause.
The heat exchanger is the component inside a gas furnace that separates combustion gases from the air that circulates through the home. A crack or failure in the heat exchanger is a serious issue, not because the furnace stops working immediately, but because combustion byproducts can enter the airstream. We inspect the heat exchanger as part of any furnace service call and as a standard part of a seasonal heating tune-up. If the inspection turns up a problem, we explain what was found and what the options are before any work proceeds.
We cover Seguin and the communities around it throughout Guadalupe County and the surrounding area. That includes McQueeney, Geronimo, Lake Dunlap, Kingsbury, and Marion. If you are in one of those communities and need heating or cooling service, call (830) 590-9782 and we will confirm we can get to you.
Local means we care what the neighbors think of our work, and that holds whether the job is in Seguin itself or in one of the towns nearby. We handle residential calls, rental properties, and commercial buildings across the area. Your system is in good hands with us.
We walk through both options clearly when the diagnostic points to a decision between repair and replacement. We explain what the repair involves, what it costs, and what the remaining life of the equipment looks like so you have what you need to make an informed call. If you need that in writing for a property file or an owner approval, let us know.
A problem that shows up only after the system has been running points to a component that fails under heat or load conditions. Capacitors, motors, and electrical controls can test fine when cold and fail once they reach operating temperature. A technician who knows this will let the system run during the diagnostic rather than testing it cold and declaring it fine.
Yes. We can provide documentation of the work performed for a property file. If you manage multiple properties and need records kept for each address, let us know when you call and we will confirm how that is handled.
Changing the air filter on a regular schedule is the most impactful thing a property owner can do between visits. A clogged filter restricts airflow and forces the system to work harder than it should. Keeping the area around the outdoor condenser clear of debris and making sure supply and return vents are not blocked also helps.
Yes. We work on heating and cooling systems regardless of who installed them. The brand, the installer, and the age of the equipment do not affect our ability to diagnose and service it. Call (830) 590-9782 and let us know what you have.
Yes. Mini-split and ductless systems are a regular part of what we handle, whether that is a repair on a system that has stopped heating or cooling, a maintenance visit, or a new installation for a room or space that does not connect to the central duct system. Call (830) 590-9782 and describe the equipment and we will confirm what the visit involves.
Once a year at minimum, and twice a year is better. A fall check before the heating season and a spring check before the cooling season catch problems at the point when they are easiest and least expensive to address. Systems that run hard through long summers benefit from that pre-season attention.
Equipment that has gone without maintenance tends to accumulate the same set of problems: dirty coils that reduce efficiency, capacitors that are on their way out, condensate drains that have partially blocked, and refrigerant levels that have drifted. None of these are dramatic failures on their own, but together they add load to the system and shorten its working life. A single maintenance visit usually surfaces all of them at once.
Permit requirements depend on the scope of the work and sometimes on whether the equipment sits inside the structure or outside it. We confirm what applies at your address before the job is scheduled, and where a permit is required, code-compliant HVAC work on every job means we handle that process as part of the installation. You do not need to manage it separately.
Sizing is based on the characteristics of the space: square footage, ceiling height, insulation, window area, and the local climate load. We do not size by guessing or by matching the old unit's tonnage without checking whether that size was correct to begin with. HVAC work sized and installed the way the manual calls for is the standard we apply on every replacement job.
Call (830) 590-9782 and tell us what the property is doing. Magnum Heating & A/C will ask the right questions, give you a clear rate, and get the work moving. We are here every day from 9:00 AM to 9:00 PM.
We also take work in: Cibolo, Schertz, San Marcos.
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 Seguin and across Guadalupe 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 Seguin 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 |
| Guadalupe 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 | Seguin 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