I have a 1994 Chevy S10, 2 wheel drive, 2.2 motor. I have a problem with the haet, the heater turns on and off. I replaced the thermostat twice and it worked fine for a while then stopped working. Now it turns on for a while then turns off for a while. Also the car is starting to over heat, the needle goes to hot then come back down to normal. I wanted to get some opinions and thoughts from everyboody on what it could be. Thanks

The heat inside turns on and off? You probably have a short or the fan switch is going.

The overheating... hmm... clogged radiator, plugged hoses, bad coolant mix, fan clutch, could be many things in an S-10 that old.

The fan I think is fine, cause I get constant air it just gets cold at times and warm at times. There is no mix it's streight anti freeze, if the radiator is clogged could that effect the heat?

Get the radiator and heater core flushed out. Also change the thermostat just to be safe.

Yes, flush it out.. and get a proper anti-freeze mix. You can't use JUST anti-freeze. It needs to be mixed with water