Temp. Problems with 90 Reatta Coupe

[Guest]

My 90 Buick Reatta has developed a temperature problem similar to the ones described in the messages posted by T. Jenkins in May. However, the problem with my Reatta is a little different. When the temperature gauge was at the 3 o'clock position while driving in slow traffic with an outside temperature of 90 humid degrees and with the air conditioner on, the ABS brake and warning lights both came on and the ABS brakes acted as if they were on all the time. Turned off the the A/C and the temperature gauge slowly came back to the 12 o'clock position,the brake warning lights went off as the traffic let up and the car achieved a speed of about 50 mph. As soon as the warning lights went off, the brakes behaved normally. Any thoughts about what may be wrong or what the problem may be would be greatly appreciated.