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(R) technician will walk you through all costs using our Straightforward Pricing(R) Guide so there are never any surprise fees.

How often should I service my HVAC system?

It's ideal to service your cooling system each spring and your heating system each fall to ensure you find small issues before they become big problems.

How often do I need to change my HVAC filter?

Your filter should be changed every one to three months, depending on conditions in your home and your region's climate.

Do you offer purchase financing?

We work built relationships with several lenders to ensure our customers are able to restore comfort in their homes. Ask your technician about your financing options.

What are the advantages of a smart Thermostat?

Smart thermostats learn a household's patterns and adjust heating and cooling according to when a home is occupied, give homeowners the ability to control the thermostat remotely, and enable homeowners to reduce their energy use, saving you money.

HVAC means Heating, Ventilation, and Air Conditioning. HVAC systems refer to air conditioners, furnaces, and any unit that cools indoor spaces during the summer and warm them in the winter. In general, an HVAC system takes in air, heats or cools that air, and blows it into a room or any indoor space. While many homes have separate air conditioning and heating units, others have a heat pump that cools and heats the house. Not only do HVAC systems maintain desired temperatures, but they also improve indoor air quality and regulate humidity levels. But most importantly, these units provide comfort all year round.

What is a SEER Rating?

The SEER (seasonal energy efficiency ratio) is a measure of the efficiency of your heating and cooling system.The higher the SEER rating, the more efficiently a unit operates. The SEER rating of any given unit can range anywhere from 13 to 21.

Bringing Comfort Home

With Expert AC Services

One Hour Air Conditioning & Heating® of Baltimore

4.8

(191 reviews)

Heating & Air Conditioning

Services By One Hour

View More Services

HVAC Repair, Installation & Maintenance

Heating, AC & Furnace Repairs in Baltimore, MD

When homeowners want a reliable heating or air conditioning system that they don’t have to think about, they call One Hour Heating & Air Conditioning. We are the premier HVAC service provider in the United States for a simple reason: we actually care about your comfort.

At One Hour, we respect you, we respect your time, and, most importantly, we respect the trust that you put in us to keep your home comfortable. It’s why we back all of our work with a 100% customer satisfaction guarantee for two years, and it’s why we’re always on time—guaranteed.

We Have a Reputation

For Being Punctual, Friendly and Knowledgeable

4.8

(191 reviews)

Cecilia “CC” Sanders

06-27-2025

“Absolutely amazing! Super responsive/communicative, very prompt getting us on their schedule even though we're in the middle of an intense heat wave. Technicians were extremely knowledgeable, and very kindly answered all of our questions. It took barely two days from my first phone call for: a consult/assessment to be scheduled and completed, the problem diagnosed, AND the financing sorted out. And installation of a whole new furnace-AC combo was completed basically one day after that. VERY fast and thorough. And they were completely transparent about all of the costs from the jump. Furthermore, the technicians were really sweet with our anxious dog, and were a pleasure to have in our home. The new AC is working great already. Thanks, Jimmy, Chris, and Chris!”

Gabriela Kahrl

06-23-2025

“The One Hour Heating and Cooling team spent the entire day meticulously installing our new A/C. We couldn’t be happier with the service! Jimmy Rico and his crew provided friendly, competent, and expert service. They were a joy to have. Special thanks also to Gilmer Rojas Rodriguez who gently gave us the bad but expected news about our over 20 year old A/C unit needed to be retired and also to Allen Powell who was a font of wisdom and sold us our new unit. Looking forward to seeing our regular technician Stephen Scott for maintenance in coming months. Thanks for taking such good care of us!”

Kathy Balchunas

06-18-2025

“Came on time. Very knowledgeable. Friendly and informative.”

Kathleen “Kat” Anderson

06-10-2025

“Mr. Rojas did an excellent job explaining the issue to me.”

Mark Kuhn

10-02-2024

“Steve did an excellent job, explaining everything in language I could understand Very knowledgeable”

Bruce Bohl

09-12-2024

“Stephen was VERY THOROUGH inspecting our Heat Pump system. Checked many of the settings including some initial ones that the original contractor missed. Any, and I mean ANY questions I had he spent time clearing my mind of mis-conceptions as I usually want to know why something is doing whatever. I was very impressed and will hope he visits on the next checkup.”

Anna Kilduff

09-11-2024

“Nice guy! Did a thorough investigation of the problem.”

Derek Stephenson

09-10-2024

“Very professional, attention to details, very good customer experience provider, listener, communicator and others”

Declan Smalley

08-30-2024

“Great service all around by Stephen!”

Bruce Zinck

08-15-2024

“Stephen has been the best by far. So personal and pays attention to details. I requested him on this recent checkup. I will request him again for my Winter check up later in the fall early winter. I have never had a bad technician so far. Stephen took time to make sure everything is checked thank you”

HVAC Services You Can Count On

Our customers love what we do because we treat them like the neighbors they are to us. While we carry the One Hour name, we’re an independently owned and operated business with a personal investment in the local community. We back our work with a 100% satisfaction guarantee, provide StraightForward® pricing guides for your benefit, and will pay you back for being even one minute late to an appointment.

Here For You

When You Need Us Most!

Yellow One Hour Heating & Air Conditioning service van with company branding and slogan.

'Round the Clock Availability

No matter the hour, you can trust One Hour to be there to help you when you get hit with the unexpected.
100% Satisfaction Guarantee

We guarantee our materials, labor, and craftsmanship for up to two years from the date of your service.
StraightForward Pricing® Guide

Before we start any work, we discuss your available options so you know exactly what you are getting and how much it will cost. No hidden fees!
Always On Time…Or You Don’t Pay A Dime!®

We understand your time is valuable, so we promise to arrive at your home within the predetermined time window that you select, or your service call is free.