Hours: 24 Hour Answering Service

MD (301) 260-6000 VA (703) 777-9211

How can we help?

Choose Mannix Heating & Cooling to fulfill your AC repairs, services, and installations across Montgomery Village, Gaithersburg, Rockville and Olney, MD as well as Chantilly, Centreville, and Dulles, VA. As a family-owned and operated business, we understand that you want your loved ones to comfortable in the heat of summer. To avoid experiencing issues with your AC equipment during the hottest months, we recommend all AC systems undergo a routine maintenance appointment. Our extensively trained technicians will thoroughly analyze and clean your system. Don’t panic, call Mannix!

We’ve Got You Covered for AC Services

Get in touch with Mannix Heating & Cooling today at (703) 777-9211 for personalized service that you can always rely on. Our team will offer affordable solutions to your residential or commercial AC system concerns and work within your timeline to get the job completed. Let us solve even the toughest of AC repairs with ease. As our NATE-certified technicians are industry pioneers, they have handled a wide array of both common and complex AC system challenges.

Reliable AC Service from Mannix Heating & Cooling

As Gaithersburg, MD, Chantilly, VA and their surrounding areas’s leading HVAC company, Mannix Heating & Cooling will handle your AC system installations and replacements with ease. Are you looking for an upgrade to your current system? We offer top-of-the-line Carrier products that are sure to impress. Don’t let just any old HVAC company handle a system as important as your AC, trust in Mannix Heating & Cooling. Our crew of professionals will get the job done right the first time.

AC Service, Air Conditioning Repair & Cooling Services Rockville, MD, Chantilly, VA, Olney, MD, Centreville, VA, Gaithersburg, MD & Dulles, VA

Air Conditioner Repair Rockville, MD | AC Installation Centreville, VA | Heating Service Dulles, VA

Heating ServiceAC RepairAir Conditioner RepairFurnace RepairAir Conditioning Repair ∴ Chantilly, VA ∴ Montgomery Village, MD ∴ Gaithersburg, MD

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Customer Reviews

Shondra J ones

They were lifesavers!!! My furnace went out and after three days of dealing with the home warranty company and the unscrupulous vendor they sent to my home, I called Mannix. The service technician was friendly, efficient but most of all honest. He found the problem after twenty minutes, saving me thousands in unnecessary replacement costs. It is refreshing to know that honest people still exist.

Lynne Wilson

I contacted Mannix from a referral of a friend who has benefitted from the excellent service this company provides. I found out a couple I know in Vienna had their heat pump stop working a few months ago and needed to be replaced. I called up the Mannix office later in the day on Monday 11/30/20 and provided information needed. I had a proposal in my email the next morning 12-01-20. This will enable me to discuss with my friends how they wish to proceed with fair financing options available too. This is EXCELLENT customer service and I would like Mr. Mannix to know that Sarah is an amazing professional face for his company. I plan to become a customer of theirs by signing up for the annual maintenance plan which is very reasonable priced. Sincerely, Lynne Wilson

Philip Slingerland

Been a happy Mannix customer for a few years now, but recently had them replace our aging HVAC system. The whole process was very painless, from Eric helping us decide which system was right for our home, to the efficient and professional installation by Billy and Matt. I am very pleased with the new system and very impressed with the level of service, communication, and detailed information I received from everyone involved. Highly recommend!


Before dealing with Mannix I used two very well-known and “reputable” HVAC companies who did nothing but rip us off over the years. I was frustrated and found Mannix Heating & Cooling about 10 years ago. They installed a new HVAC system in my old home, and installed a water heater and various other items in my new home. They also have been doing yearly maintenance for years. Their employees are the most honest, reliable, and knowledgeable individuals in this industry. We recently had an issue with our HVAC system and they came out within a few hours on an emergency call. The technician was prompt, kind, professional, and very fair. He figured out what was wrong with our system quickly and remedied it immediately. Do not hesitate to call them if you need anything–you won’t regret it!

Wendy Collins

Mannix has always been professional from service calls to repairs and replacements. The technicians are always polite and knowledgeable. They consistently exceed our expectations.

Gary Hendricks

Mannix proved very responsive in fixing my A/C system. The tech, Erick, was very professional by taking the time showing and explaining to me the system problem prior to taking action replacing the coil. Ashleigh, customer service, was excellent in addressing and following through on concerns in order to achieve total customer satisfaction.

M. Reyzer

My 24-year-old heat pump finally decided to stop working. I sent a request for a replacement estimate late one night through the Mannix website and received a phone call early the very next morning to set up an appointment. Eric Holzworth stopped by my house the next day to go over my options. He was wonderful and so easy to work with and answered every question I had. He definitely listened to me and my concerns did not push me into purchasing a high-end system which I didn’t need. The technicians arrived at 8am and were finished with the entire installation by 1pm. They were very courteous and left my house in pristine condition. I HIGHLY recommend Mannix! They always returned my calls and emails right away, and Eric made sure I received all of my equipment on time–even with Carrier factory delays/limited supplies due to COVID. So glad I chose Mannix. I love my brand new Carrier system and my cold house during these hot and humid days.


We were in desperate need of a fix on our AC system during the July heatwave. The issue arose on a Saturday. Mannix came to the rescue in short order, fixed it, and at a reasonable price.

Silvio G was the technician, and he was GREAT.

We would definitely use Mannix again!

Patricia Ryan

I have been using Mannix for years. They have replaced my HVAC system and I have them do maintenance twice a year. The past couple of visits have been done by Ramiro. He is professional, polite, knowledgeable, and very helpful in assisting me with tips on the best ways to operate my system. Today, he installed a water safety device and taught me exactly how it works and how to reset it. I’m so impressed with him! I will continue with Mannix for years to come as I find them to be very reputable and reliable. Thank you!

Rachel Craft

I’ve been using Mannix for years and have never been disappointed. They’ve replaced my HVAC, hot water heater and installed a humidifier on my furnace. Whenever I need them, they can get me on the schedule in a timely manner. All the personnel are great and I trust Jerry and his team with their recommendations and the work they do. Would highly recommend.

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