Smith -Dahlquist, Inc. Heating & Air Conditioning Smith -Dahlquist, Inc. Visit Website 994 Crosby Avenue Sycamore, IL 60178 (815) 895-5470 (815) 895-3659 (fax) Facebook About About Family owned HVAC & gas Fireplace provider servicing DeKalb, Ogle, Lee, Kane & Boone counties. Quality service with up front competive pricing.