ilmbg,

In my area, the Washington DC and surrounding suburbs in VA and MD, there is a consumer magazine and associated website that rates Heating and A/C contractors.

Like anything else, you still must do your due diligence and investigate. The Better Business Bureau and in my case, my County provides an on-line source to determine complaints made and resolution for all businesses within the County.

YMMV

ilmbg,

Your neighbors are usually the most reliable sorce there is.

source

I really should proofread....