95 Chevy Lum, hot temp. gage, cold air

Two days ago my car started easily on a cold day. Within a couple of miles the temp. gauge shot way up and temp. light came on. Cold cold air blowing out. Stopped car at post office, opened coolant holder thinking I might need more. It was full. I blew in it. Got back in the car and all was well. Next day drove about 100 miles, no problems. Today, same prob. Cold day, started fine, temp. gauge shot way up to hot, temp. light on, cold cold air blowing through. I had a new heater core put in the car two full months ago which was working great. Rough idle, but that is nothing new. No smoke or smells. No other lights.



Any ideas? And is the car safe to drive when the temp light is on like that?



Thanks - from clueless Chrissy in Connecticut

First simple explanation is a sticking thermostat, try replacing that first.

Sticking thermostat…Interesting, and sounds inexpensive. Is that something a beginner can do herself?

Also, since this posting, the car went back to its normal temp. with warm air.

Thanks for the information. Chrissy