As temperatures rise in much of the country, the confidence of Air Conditioning Contractors of America members is increasing as well.

For April, the association’s Contractor Comfort Index of the HVAC market is 81 — the highest number the index has reached in its four-year history. A year ago, the index was 71.

The index is based on a survey of ACCA members, whom are asked about new HVAC sales business prospects, existing HVAC construction business activity and expected staffing levels in the near term.

Averaged into a number on a 100-point scale, any figure above 50 says a majority of members see business as positive.