Heat Pumps
Mitsubishi ductless split heat pumps and ducted heat pumps.
Sheet Metal Fabrication
We supply contractors with their ductwork.
Custom Metal Fabrication
We supply businesses with custom metal fabricated parts.
Air Conditioning
Looking to add central air to your home?
Welcome to M.J. Williams Heating & Air Conditioning, Inc.
M.J. Williams Heating & Air Conditioning, Inc. is a full service HVAC contractor serving both residential and commercial customers in Massachusetts and Northeast Connecticut.
We provide prompt, professional and affordable service and installations of all your heating and air conditioning systems, and are available for maintenance and emergency service.
Some of Our HVAC Services Include:
- Heat Pumps – DUCTED Whole house systems, and Ductless for individual room conditioning
- Central Air Conditioning – New installations, replacements, and repairs
- Custom Sheet Metal
- Duct Fabrication
Mass Save® is a collaborative of Massachusetts’ electric and natural gas utilities and energy efficiency service providers including Berkshire Gas, Cape Light Compact, Eversource, Liberty, National Grid, and Unitil.
Energize ConnecticutSM is an initiative dedicated to empowering Connecticut to make smart energy choices, now and in the future.
We stand behind our work 100%.
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Mike installed ducted minisplits in our 300+ yr old house. The work was excellent, The price was good. Mike works his butt off to do it right. Working in a... read more
cmhyland100
May 1, 2025 -
Mike’s work is top quality! He fabricates his own ductwork and ensures a perfect fit! He’s also a super great guy and was really easy to work with! Highly recommend!
Chelsea Giampietro
September 2, 2024 -
When it comes to professional, proper installers, I can't say enough good things about the team over at M.J. Williams. Great communication, Pricing as quoted with no surprises. Finished work... read more
Dave
September 2, 2024 -
I highly recommend this company. Very professional & reasonable prices. You won't go wrong.
Mary LeBlanc
March 21, 2023
Project Gallery
Real photos from our job sites.
View gallery of our completed projects.
Our HVAC Services
Residential HVAC work ranges from antique homes as small as 800 sq. ft., to ultra contemporary, 18,000 sq. ft. homes. Whether your home is large or small, we can provide you with everything you need to keep your heating and cooling systems running smoothly and efficiently.
Commercial HVAC work includes: offices, retail spaces, restaurants and more.
Our reputation of providing excellent work at a reasonable price, and being honest and trustworthy has allowed us to continually serve our customers since 1988.
