ATR72 Captain reports that the aircraft that his company operates have inoperative cabin cooling systems which allow cockpit temperatures to exceed 100 degrees in the midday heat. Cabin temperatures exceed 90 degreesand repairs are being made at a slow rate.

Narrative

I was dispatched to operate an afternoon turn. The OAT was 33C at the departure time. By the time we completed the turn; the OAT was 35C. All ground equipment was found to be working properly. I wrote up the aircraft after this turn; for the high cockpit and cabin temperature. The cockpit never cooled below 105F and the cabin was 90 degrees in the forward cabin. These readings came from my personal thermometer; because the aircraft temperature gauge was pegged. I became aware last evening that the maintenance corrective action in this case was to MEL the cockpit temperature gauge. I am not seeing this as a corrective action; but rather a blatant abuse of power. I did some further research on this ATR heat topic and found that the maintenance has been fixing the ATR aircraft at a slow rate to address this known heat problem. The rate is 1/2 aircraft per night. At this time; only three have been completed. I would like to know which aircraft have been completed; for the purpose of accepting an aircraft in the mid day heat. In my opinion; no aircraft with a known broken ventilation problem should be dispatched under such extreme heat conditions. This serious and life threatening situation we are facing which requires immediate attention.