M & D Plumbing Heating and Air Conditioning has been serving Commack and the surrounding Suffolk County communities since 2018, handling the full range of residential and commercial heating and cooling work. Whether you need a same-day repair, a seasonal tune-up, a full system replacement, or help with an after-hours emergency, our team is ready to respond. We work with homeowners, landlords, property managers, and business owners across the area, and every job is handled by qualified HVAC technicians who know Long Island's homes and systems inside and out. Quick response. Straight pricing. No surprises at the unit.
We've serviced and replaced systems all over these neighborhoods, and we've built our service menu around what Long Island customers actually need. From a furnace that stops mid-winter to a central air system that needs a full replacement, we cover it all.
Our core services include:
If your heating or cooling system needs attention, we have the experience to diagnose it accurately and fix it right. Give us a ring and we'll take care of it.
Staying ahead of HVAC problems keeps your home comfortable, and that starts with knowing who to call when your air conditioner stops keeping up. We handle everything from a unit blowing warm air or cycling too often to a full central air installation or system replacement.
When we come out for an AC repair call, we diagnose the problem thoroughly. That means checking the condenser and compressor, testing for refrigerant leaks, inspecting the evaporator coil, and tracing any airflow or uneven-temperature issues back to their source. Same-day availability is often possible for urgent calls, so you are not waiting through a hot Suffolk County afternoon for help to arrive.
For routine service, a seasonal AC tune-up catches small problems before they turn into expensive repairs. And when a system is past its useful life, we walk you through replacement options with no-pressure estimates, priced up front, so you know exactly what you are getting into before any work begins.
Our technicians know the homes and systems in this area, and furnace calls are some of the most common work we do on Long Island. A furnace that stops working, blows cold air, or shuts off unexpectedly is not something you want to sit with when temperatures drop.
We handle furnace repair for all makes and models, including air handler and blower service, airflow troubleshooting, and heat exchanger diagnostics. Emergency furnace repair is available when you cannot wait, and we work to get your heat restored as quickly as possible.
Annual furnace maintenance is the best way to avoid unexpected breakdowns. A pre-season tune-up catches worn components, confirms safe operation, and helps your system run more efficiently. When a furnace has reached the end of its life, we handle full system replacement and installation, including energy-efficiency upgrades where they make sense for your home. Clear communication from the first call to the final test is how we approach every job, so you always know what we found, what we recommend, and what it will cost.
Heat pumps handle both heating and cooling in a single system, which makes them a practical choice for Long Island's climate, where you need reliable performance on both sides of the year. We service and repair heat pumps that have stopped heating, stopped cooling, or are running inefficiently, and we handle new heat pump installation and replacement as well.
A heat pump repair call starts with a full diagnostic: refrigerant leak checks, airflow testing, and a look at the control systems to find the root cause. For homes looking to add zoning and comfort-control systems, heat pump technology pairs well with ductless configurations that let you manage temperatures room by room.
We're ready to get your heating and cooling running again, whether that means a repair visit today or a full installation scheduled on your timeline.
Long Island's housing stock shapes the work we do every day. Older homes throughout Commack and the broader Suffolk County area were built with boilers, radiators, and oil heat. Many have no ductwork at all. And as energy costs and state policy push homeowners toward cleaner, more efficient systems, conversion and retrofit work has become a core part of what we handle. The three services below come up constantly in this area, and we have developed real depth in each of them.
Many homes in this part of New York still rely on hot-water baseboard heat, steam radiators, or radiant systems that have been running for decades. We repair boilers that have stopped producing heat, maintain systems that are still running well, and replace aging units when the time comes. Radiant heat repair is part of our regular workload. If your boiler is making noise, losing pressure, or leaving some rooms cold, a diagnostic visit is the right first step.
The Northeast carries the vast majority of the country's oil-heated homes, and Suffolk County is no exception. Many homeowners are ready to move off oil, whether to reduce dependence on fuel deliveries, lower long-term operating costs, or take advantage of heat pump technology that handles both heating and cooling. We handle the conversion of the heating equipment itself, from the old oil-fired system to a new gas or heat pump setup, and we walk you through the options so the decision makes sense for your home and budget.
Older homes without ductwork, sunrooms, additions, and spaces that never quite reach the right temperature are ideal candidates for ductless mini-splits. A mini-split system delivers heating and cooling directly to the space without requiring any ductwork, which makes installation cleaner and faster than a full central system retrofit. We handle installation, repair, and service for ductless systems, and we can design a zoning setup that gives you independent control over different areas of the home.
Leaky or damaged ducts are one of the most common reasons a home has uneven temperatures or higher-than-expected energy bills. We inspect ductwork, seal leaks, repair damaged sections, and replace duct runs that have deteriorated beyond repair. If some rooms are always too hot or too cold, the duct system is often the place to start.
A thermostat that is not working correctly can make an otherwise healthy HVAC system behave erratically. We replace faulty thermostats, install programmable and smart thermostats, and make sure the wiring and settings are dialed in before we leave. A properly configured smart thermostat gives you better comfort control and can meaningfully reduce energy use over time.
The air inside a home can carry more irritants than most people realize. We install whole-home air purifiers, air filtration systems, air scrubbers, and whole-home humidifiers that work with your existing HVAC equipment to improve what your family breathes every day. For Long Island homes that run their systems hard through both humid summers and dry winters, indoor air quality equipment makes a real difference. Call and we'll get the air running right.
We've served this area long enough to know what works, and the answer is consistent: systems that get regular maintenance last longer, break down less often, and cost less to operate. We offer spring and fall tune-ups, annual HVAC inspections, and pre-season service calls for both residential and commercial customers.
A tune-up visit covers the key components, confirms the system is operating safely and efficiently, and flags anything that looks like it could become a problem. We treat your home and its system the way we would our own, which means we give you honest feedback, not a list of upsells.
Comfort problems don't wait, and neither do we. When your heat goes out in January or your air conditioner stops working on a July weekend, you need someone who can actually show up. We offer same-day and after-hours emergency service for no-heat and no-cool situations throughout Commack and the surrounding area.
Quick response. Straight pricing. No surprises at the unit.
Every emergency call starts with an honest diagnosis. No-pressure estimates, priced up front, mean you know what the repair will cost before we start. We do not use an emergency as an opportunity to oversell. We find the problem, explain it clearly, and fix it.
What sets our technicians apart is straightforward: they show up prepared, diagnose accurately, and get commercial systems back online without unnecessary delays. We serve offices, retail spaces, restaurants, and multi-unit properties throughout Commack and across Suffolk County.
Commercial HVAC systems run harder and have less tolerance for downtime than residential equipment. We handle commercial repair, maintenance, installation, and replacement with that reality in mind. Whether you manage a single storefront or a portfolio of properties, we can set up a maintenance schedule that keeps systems running and catches problems before they interrupt your business.
Property managers and business owners can reach a real local person who knows the area when they call. We are locally owned and personally accountable for every job we take on.
We've been doing this work in Commack since 2018, and the way we operate has not changed. Every call is handled by qualified HVAC technicians who know Long Island's housing stock, its climate, and the systems that run in homes and buildings throughout this part of New York.
We are a family-run, locally owned business. When you call, you reach someone who knows the area and cares about the outcome. We built this company on honest work and straightforward communication, and that is still how we run every job.
We know cost is one of the first things on a customer's mind. Our approach is simple: a technician assesses your system, explains what they found, and gives you clear pricing before any work begins. No hidden charges, no surprise totals at the end of a job.
No-pressure estimates, priced up front, are standard on every call, whether it is a repair visit or a full system replacement. You make the decision with full information, and we get to work when you are ready.
We are based in Commack and serve customers throughout Suffolk County and the surrounding communities. If you are nearby, we can likely get to you quickly.
Areas we serve include:
We serve Commack as our home base and cover communities throughout Suffolk County, including Hauppauge, Smithtown, Kings Park, Dix Hills, Huntington, Melville, Brentwood, Nesconset, and Deer Park. If you are not sure whether we reach your address, call us at (631) 623-9591 and we will confirm quickly.
Yes. Same-day availability is often possible for urgent repair calls, and we offer emergency service for no-heat and no-cool situations throughout Commack and the surrounding area. Call (631) 623-9591 early in the day to give us the best chance of getting a technician to you the same day.
Turn the system off at the thermostat to avoid any further strain on the equipment, check that the filter is not completely blocked, and call us at (631) 623-9591. We will ask a few quick questions about what the system is doing and get a technician scheduled as fast as possible.
We are available every day from 8:30 AM to 9:30 PM, including weekends. For heating and cooling emergencies, call (631) 623-9591 and we will work to get someone to you as quickly as we can.
Yes. We are open seven days a week from 8:30 AM to 9:30 PM, so Saturday and Sunday service calls are handled the same way as any weekday. Call (631) 623-9591 to schedule or to request same-day help.
Call us at (631) 623-9591. We will ask about your system, your location, and what it is doing, and then get you on the schedule. The faster you call, the better our chances of reaching you the same day.
It helps to know the make and model of your system if you can find it on the unit, a brief description of the problem, and your address. You do not need to have all of that information to call. We will ask the right questions to get the visit set up correctly.
We give you clear pricing before any work begins. If the scope changes once the technician is on-site, we talk to you about it before moving forward. There are no hidden charges or surprise totals at the end of a job.
The price covers the diagnostic assessment, the technician's time, and the repair or service work agreed to before we start. Parts and materials are included in the estimate we give you up front. We do not add line items after the fact.
M & D Plumbing Heating and Air Conditioning is ready to help with whatever your heating or cooling system needs, from a quick repair to a full system installation. We serve Commack and the surrounding Suffolk County area with honest work, qualified technicians, and straightforward pricing.
Quick to arrive. Careful with your home. Tidy when we leave.
Call (631) 623-9591 to request a quote or schedule your service visit today.
We handle the full range of residential and commercial heating and cooling work in Commack and across Suffolk County, from a same-day repair call to a full system replacement. Every job is performed by qualified HVAC technicians who know Long Island's homes, its climate, and the equipment that runs in them. The table below outlines what each service covers, who it fits best, and a practical note to help you decide where to start. Call us at (631) 623-9591 and we will walk you through the right option for your situation.
| System Service | What's Included | Best Suited For | Things to Know |
|---|---|---|---|
| Ductless Mini-Split Installation | Single-zone and multi-zone setups, Heating and cooling in one system, No ductwork required | Older homes without ducts, additions, sunrooms, or rooms that never reach the right temperature | Installation is typically cleaner and faster than retrofitting a full central system into an existing home |
| Emergency HVAC Service | Same-day and after-hours availability, No-heat and no-cool response, Honest diagnosis before any repair begins | Anyone whose heat or air conditioning has stopped working and cannot wait | We are available every day from 8:30 AM to 9:30 PM, including weekends |
| Heat Pump Repair and Service | Refrigerant leak checks, Airflow and control system testing, Heating and cooling mode diagnostics | Homes running a heat pump for year-round comfort on a single system | Heat pumps handle both seasons, so a problem in one mode often affects the other |
| Oil-to-Gas and Heat Pump Conversion | Removal of oil-fired equipment, Gas or heat pump system installation, Guidance on efficiency and operating costs | Homeowners ready to move off oil heat and reduce dependence on fuel deliveries | The Northeast carries more oil-heated homes than anywhere else in the country; conversion work is a regular part of what we do here |
| Thermostat and Smart-Control Installation | Programmable and smart thermostat installation, Wiring and settings configuration, Compatibility check with existing equipment | Anyone with an erratic system or who wants better control over comfort and energy use | A properly configured smart thermostat can meaningfully reduce energy use over time |
| Full System Installation and ReplacementMost Popular | Central AC and furnace replacement, Heat pump system installation, Energy-efficiency upgrade options | Homeowners whose system is aging, failing repeatedly, or no longer cost-effective to repair | We provide clear pricing before any work begins so you know the full cost up front |
| Boiler and Hydronic Heating Service | Hot-water baseboard and steam systems, Pressure and noise diagnostics, Radiant heat repair and maintenance | Older Long Island homes running boilers, radiators, or radiant floor heat | Many Suffolk County homes have boiler systems that have run for decades and benefit from regular service |
| Seasonal Maintenance and Tune-Ups | Spring and fall system tune-ups, Key component checks and safety confirmation, Pre-season performance review | Any homeowner or property manager who wants to avoid unexpected breakdowns | Systems that get regular maintenance last longer, break down less often, and cost less to operate |
| Heating and Furnace Repair | All makes and models, Blower and air handler service, Heat exchanger diagnostics | Any home or business that has lost heat or is getting inconsistent warmth | Emergency furnace repair is available when you cannot wait for a scheduled visit |
| Ductwork Repair and Sealing | Leak detection and sealing, Damaged section repair or replacement, Airflow balancing | Homes with uneven temperatures, high energy bills, or rooms that never feel right | Leaky ducts are one of the most common and overlooked causes of comfort and efficiency problems |
| AC Repair and Service | Diagnostic and refrigerant checks, Condenser and coil inspection, Airflow and cycling troubleshooting | Homeowners with a unit blowing warm air, cycling too often, or not keeping up | Same-day availability is often possible for urgent calls during the cooling season |
| Indoor Air Quality and Air Filtration | Whole-home air purifiers and scrubbers, Air filtration system installation, Whole-home humidifier installation | Families concerned about allergens, dust, dry air, or what the system is circulating | Long Island homes run their systems hard through humid summers and dry winters, making air quality equipment a practical upgrade |
How do I know whether to repair or replace my heating or cooling system?
Age and repair history are the two biggest factors. A system under ten years old that has been maintained and has a straightforward problem is usually worth repairing. When a system is older than fifteen years, has needed multiple repairs in recent seasons, or the repair cost approaches half the price of a replacement, replacement often makes more financial sense. We walk through both options with you honestly and give you clear pricing on each so you can make the call with full information.
What are the signs that my air conditioner or furnace may need to be replaced soon?
For an air conditioner, watch for rising energy bills without a change in usage, frequent repair calls in the same season, uneven cooling across the home, or a system that runs constantly without reaching the set temperature. For a furnace, warning signs include unusual noises, short cycling, cold spots in the home, or a heat exchanger that a technician has flagged as cracked or compromised. Neither list is exhaustive, but any of those patterns is worth a diagnostic visit.
How often should I schedule maintenance or a tune-up?
Once a year per system is the standard recommendation, and timing matters. For a central air system, a spring tune-up before the cooling season starts is ideal. For a furnace or boiler, a fall visit before you need heat is the right window. If you run a heat pump year-round, one visit in spring and one in fall covers both modes. Regular maintenance is the single most reliable way to avoid unexpected breakdowns and keep operating costs in check.
Transparent Upfront Pricing
We give you clear pricing before any work begins, whether it is a repair call or a full system replacement. No hidden charges, no surprise totals at the end of the job.
Why is one room in my home always hotter or colder than the rest?
Uneven temperatures usually point to one of a few causes: leaky or undersized ductwork, a zoning issue, a dirty filter restricting airflow, or equipment that is not sized correctly for the home. Ductless mini-splits can solve the problem in rooms that have never been comfortable, and duct sealing or repair often resolves it in homes with existing ductwork. A diagnostic visit gives us a clear picture of what is actually happening before we recommend a fix.
What does a seasonal tune-up actually cover?
A tune-up visit covers the key mechanical and electrical components of the system, confirms safe and efficient operation, checks refrigerant levels on cooling equipment, inspects the heat exchanger on a furnace, and tests controls and safety switches. We also look at the filter, the blower, and the coils. If something looks like it could become a problem before the next season, we flag it and explain what we found. The goal is to catch small issues before they turn into expensive repairs.
Can I get same-day service if my heat or air conditioning stops working?
Same-day availability is often possible, especially if you call early in the day. We offer emergency service for no-heat and no-cool situations throughout Commack and the surrounding area every day from 8:30 AM to 9:30 PM, including weekends. Call us at (631) 623-9591 and we will ask a few quick questions about the system and get a technician scheduled as fast as we can.
Same-Day and Emergency Availability
We are available every day from 8:30 AM to 9:30 PM, including weekends, and same-day service is often possible for urgent heating and cooling calls throughout Commack and Suffolk County.
What causes a system to short-cycle, and is it serious?
Short-cycling means the system turns on, runs briefly, shuts off, and repeats the cycle without completing a full heating or cooling run. It can be caused by an oversized system, a dirty filter blocking airflow, a refrigerant problem, a faulty thermostat, or a control board issue. It is worth addressing promptly because short-cycling puts extra wear on the compressor and other components and raises energy costs. A diagnostic visit identifies the root cause so the fix addresses the actual problem.
How do ductwork leaks affect my energy bills and comfort?
Leaky ducts allow conditioned air to escape into unconditioned spaces like attics, crawl spaces, or wall cavities before it ever reaches the rooms you are trying to heat or cool. The system works harder to compensate, energy bills go up, and some rooms never reach the right temperature. Sealing and repairing ductwork is one of the more cost-effective improvements a home can get, and the comfort difference is often noticeable right away.
Experienced With Older and Newer Systems
Long Island's housing stock ranges from decades-old boiler systems to newer heat pump installations, and our technicians are comfortable working on all of it.
What is involved in switching from oil heat to a heat pump or gas system?
The conversion involves removing the existing oil-fired equipment and installing a new gas furnace or heat pump system in its place. We handle the heating equipment side of the job. We walk you through the options based on your home's layout, existing ductwork, and what makes the most sense for your long-term operating costs. Many Suffolk County homeowners are making this move to reduce dependence on fuel deliveries and take advantage of more efficient technology.
Do I need to be home when the technician comes out?
For most service calls and installations, yes, an adult should be present. The technician needs access to the equipment, may need to ask questions about what the system has been doing, and will want to walk you through the findings and pricing before starting any work. If your situation is complicated, call us and we will work out the logistics together.
How does your pricing work, and will the estimate change once the technician arrives?
A technician assesses the system, explains what they found, and gives you clear pricing before any work begins. If the scope changes once we are on-site, we talk to you about it before moving forward. There are no hidden charges and no surprise totals at the end of a job. No-pressure estimates, priced up front, are how we handle every call, whether it is a repair visit or a full system replacement.
Call (631) 623-9591 and we will help you figure out exactly what your system needs and get you on the schedule.
(631) 623-9591