Mechanical (also HVAC/Heating/Ventilation/Air Conditioning)
A-Ames, Garden Grove
A&B Plumbing Heating Air Electrical, West LA (Mar Vista)
ABM Engineering Services, Commerce, Woodland Hills
Acco Engineered Systems, Glendale
Adee, citywide
Alfa Mechanical
All Seasons Air Conditioning, Plumbing & Heating, Cathedral City
Allan Frank Plumbing Heating & Rooter, Long Beach
America 1 Plumbing Heating & Rooter, Los Alamitos
American West Services, Newport Beach
Americanthony Home Services, Anaheim
Andrus Plumbing, Heating and Air Conditioning, Laguna Beach
ARS Service Express, citywide
Berck's Family Plumbing, Heating & Air, Lake Elsinore, Temecula, Sun City, Hemet
BHI Plumbing, Heating & Air Conditioning, San Bernardino
Bob's Plumbing & Heating, South LA
Brea/Orange County Plumbing, Heating & Air Conditioning, Brea
Can-2 Heating & Air Conditioning
Clark Plumbing, Heating & Air, Van Nuys, Thousand Oaks
Cole Services, Garden Grove
County Wide Plumbing, Heating, Rooter & Air, Irvine
D&D Plumbing & Mechanical, Temecula
Dabco, Lakewood
DC Plumbing, Heating and Air Conditioning, Laguna Hills
Dial One Schilling Plumbing Heating & Air Conditioning, Signal Hill
Dial One Sonshine Plumbing, Heating and Air Conditioning, Stanton
Downey Plumbing Heating & Air Conditioning
EJ Service
Empire, Whittier, Garden Grove, Yorba Linda
First Choice Plumbing, Heating and Air Conditioning, Riverside
George Brazil, citywide - also electrical
GR Plumbing & Heating, Duarte
Heflin & Son Plumbing & Heating, Inglewood
Inland Mechanical Construction, Lake Elsinore
J & D Plumbing & Heating, Long Beach
Integrated Engineering (IE), Mid-Wilshire (Wilshire Center)
Jack Stephan, citywide
Jackson & Blanc, Irwindale
Jimmie West Plumbing, Heating & Air Conditioning, Torrance
La Salle Plumbing Heating & Air Conditioning, Torrance
Linc Service, Irvine
LK Plumbing & Heating, Studio City
Maroko & Shwe, Mission Hills
MB&A Consulting Mechanical Engineers, Burbank
Mesa Energy Systems, Irvine
Mike Diamond Plumbing Heating Air Conditioning Electrical, citywide
Murray Company, Rancho Dominguez, Newbury Park
Norwalk Plumbing Heating & Air Conditioning
Pacific Rim Mechanical
Pagel Service, San Bernardino
Pan-Pacific Plumbing & Mechanical, Irvine
Park's Mechanical Construction, Wilmington
Pete Fer and Sons Plumbing and Heating, Carson
Plumbing & Heating Credit Service, Tustin
Plumbing Specialists, Riverside
Precision Plumbing-Mechanical, Moorpark
Preferred Plumbing Heating and Air Conditioning, Palm Springs
Priority One Plumbing Heating & Air Conditioning, North Hollywood
Rawlings Mechanical, Sun Valley
RCR Plumbing and Mechanical, Palmdale, Riverside, Palm Springs, Adelanto
Redlands Plumbing, Heating & Air Conditioning
RNK International, Laguna Hills
RPB, Buena Park, Bellflower
Saddleback Plumbing, Trabuco Canyon
Santa Monica Plumbing & Heating, Santa Monica
Scott Harrison Plumbing & Heating, Stanton
Southland Industries, Long Beach
SSW Mechanical Construction, Palm Springs
Stephens Plumbing Heating and Air Conditioning, Torrance
Westcal Mechanical, Orange

Organizations
Organizations in General

California Plumbing and Mechanical Contractors Association (CPMCA), Torrance
Plumbing-Heating-Cooling Contractors of California (PHCC)
Plumbing Heating Cooling Contractors of the Greater Los Angeles Area (PHCC-GLAA)
Plumbing, Heating, Cooling Contractor's Association (PHCC) of Orange, Riverside & San Bernardino Counties, Stanton