So I have a bit of an interesting problem with my 95 Del Sol (D16Z6). Every time I add electrical draw through any interior switch, mainly the windows and hvac fan, my coolant gauge spikes. Ive cleaned all the motor grounds but this had no effect. Also, It seems to be worse once the motor is warmed up. Im wondering if anyone with more experience with the electrical system could point me in the right direction. I Have a multimeter and can do some intermediate troubleshooting but Im not really sure were to start with this so I thought id ask first

 

check the body to engine ground. take it off and SLAM it on the ground/pavement a few times, that will loosen any corrosion inside the cable.