EXHIBIT 23.3 CONSENT OF INDEPENDENT AUDITORS We consent to the incorporation by reference in this Registration Statement of Comfort Systems USA, Inc. on Form S-4 of our report dated February 24, 1998 relating to the financial statements of Shambaugh & Son, Inc. as of December 31, 1997 and for the year then ended. /s/ CROWE, CHIZEK AND COMPANY LLP April 2, 1999 II-14