Here are links to websites that may be of interest to you:

Air Conditioning Contractors of America 
www.acca.org

Energy Trust of Oregon, Inc. 
www.energytrust.org/

North American Technician Excellence (NATE) 
www.natex.org/about.htm

Building Industry Association of Washington 
www.homebuildersportland.org/consumer-information.html

Home Builders Association of Metropolitan Portland
www.homebuildersportland.org/consumer-information.html

Lennox
www.lennox.com/residential

Ruud
www.ruudac.com

Coleman
www.colemanac.com/homeowners/index.asp

Other useful sites:

Home Builder Directory

BuilderTotal.com - Builders, Contractors and Home Improvement Directory

Home Builders, Architectures, Floor Plans, Contractors and Building Software Directory

Find a contractor at Findoha.com

Home Builder Contractor

Search4Contractors.com - The Online Home Builder and Construction Web Directory