Employee was troubleshooting the Kiln 3 lube system around 9:30 AM. The temp was 81 deg F, with a heat index of 95 deg F. After returning to the shop to work on the pressure switch, EE asked for help because EE was shaking too bad to work. EE sat down to cool off but began to cramp from possible dehydration. EE was diagnosed at the ER with heat exhaustion and dehydration.