What does the One Hour mean in your company name?

The 'One Hour' in our company name indicates our guarantee to be at your home in the predetermined window quoted when you set your appointment. If we do not show up within that window, your service call fee is waived. 1. Express Appointment: This is an appointment that is scheduled during a specified one-hour time slot. You are promised that a technician will arrive at your home within this one-hour time window. You will also receive a call when the technician is en route to your home. 2. Reserved Appointment: This is an appointment that is scheduled during a specified, two-hour time slot. You are promised that a technician will arrive at your home within this two-hour time window. You will also receive a call when the technician is en route to your home. 3. Standard Appointment: This is an appointment that is scheduled during a specified four-hour time slot. You are promised that a technician will arrive at your home within this four-hour time window. You will also receive a call when the technician is en route to your home. 4. Stand-By Appointment: This appointment is for overflow situations. This appointment will not have a specified time. You will receive a call when the technician is en route to your home. 5. Emergency Appointment: This appointment is for an unspecified time after normal business hours Monday – Saturday and all day on Sundays/Holidays. Calls are dispatched in the same order they are received. You will also receive a call when the technician is en route to your home.

Do you service emergencies after-hours?

Yes, we offer emergency services 24-hours a day, year-round.

How much will my service cost?

The size and complexity of your HVAC issue will determine the cost. Because our trained, licensed HVAC technicians must diagnose the issue before we are able to quote you an accurate cost, we require an appointment to be set to complete a diagnostic on your system. Once the diagnostic is complete, your One Hour® technician will walk you through all costs using our Straightforward Pricing® Guide so there are never any surprise fees.

Gaithersburg, MD

HVAC Service you can count on

4.8

(319 reviews)

Heating & Air Conditioning

Services By One Hour

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HVAC Service Near Me
—Available 24 Hours

One Hour Heating & Air Conditioning understands that heating and air conditioning issues create uncomfortable living situations — especially when temperatures outside are extreme. Luckily, our customer specialists are on standby 24/7 to fix your urgent issues. Whether you need HVAC installation, repair, or maintenance, our HVAC service experts are ready to help.

Emergency HVAC Services

We offer 24-hour emergency HVAC services – even on weekends and holidays – to ensure you have professional support when you need it most. Arriving with service trucks stocked full of specialty parts and tools, we have the equipment needed to fix many HVAC problems on the spot. In the case that additional parts are needed, rest assured – we will do everything in our power to handle your HVAC emergency quickly and efficiently.

Give our team a call today or contact us online to request your same-day HVAC service.

Air Conditioning

Whether you need an emergency replacement, regular maintenance, or installation services, our qualified technicians have the experience and technological resources to get any HVAC job done correctly. We utilize the latest tools, products, and techniques to stay up to date with cutting-edge changes in the industry.

AC Repair

At One Hour Heating & Air Conditioning, our HVAC technicians service all major AC brands and models. Our AC repair team can fix:

Poorly insulated ductwork
Power supply breakdowns
Defective fans or thermostats
Refrigerant leaks
Frozen condenser coils
Blocked condensation drainage
AC short-cycling (turning on and off too quickly)

After inspection, we will provide a detailed estimate.

AC Installation & Replacement

There are many telltale signs that an HVAC unit might need to be replaced. If an HVAC unit is over 10-years old, smells terrible, blows warm air, or produces subpar results as energy bills keep rising, give us a call!

AC Maintenance

For optimal performance, AC units require many parts to work seamlessly together. A single problem can cause a ripple effect of issues. This is why spotting minor malfunctions is critical. With regular maintenance visits, we can ensure your HVAC system is operating smoothly and efficiently. Consider joining our Club Membership for additional customer benefits.

HVAC Services

Common Questions

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Our Happy Customers

Reviews of Gaithersburg

4.8

(319 reviews)

Diane Moynihan Stefan

03-26-2026

“Mr Gilmer was very patient explanation all the work ahead of time. Very good experience today@”

Cheryl Poole

03-26-2026

“Mr Gilmer did a fantastic job today repairing my furnace.”

Leah Henry

03-25-2026

“Gilmer and Ivory were nice and welcoming! Professional and they broke down every concern about my HVAC system.”

Nadia Kendall

03-25-2026

“I have been with One Hour for over a decade. Mr. Gilmer has worked on my HVAC system a few times now and each time he isn't satisfied with his work until everything is in peak working condition. He takes his time to explain what he's doing and he does so with pride. We are thankful for Mr. Gilmer's work and dedication to your products working in our home.”

michele murphy

03-24-2026

“Mr Gilmer was professional and explained everything to me (repairs, problems, etc)”

Wayne Simms

03-20-2026

“Mr Gilmer”

Jackie Hilton

03-19-2026

“Mr Gilmer was prompt, courteous, and knowledgable. He took time to explain his review and recommendations.”

Dean Wiles

03-18-2026

“Mr. Gilmer and William did a great job checking my HVAC and answering my questions.”

Hirad Yaldaei

03-18-2026

“Had a great experience with Mr Gilmer! Highly recommend!”

Anna Kilduff

03-17-2026

“Mr Gilmer”

Servicing your entire home

Part of the Authority Brands Family

Authority Brands is the leading provider of in-home services, building brands that support the success of franchisees as well as better the lives of the homeowners we serve and the people we employ.