[3echo9]

Temp gauge rises and falls while driving instead of rising gradually and stabilizing.

Noticed the temp through the heating vents goes from hot to cold and back to hot as the car moves.

Cooling fans are also coming on and staying on..in this 30-40 degree weather.

Noticed that the reserve tank was low and added a 50/50 mix to bring it back up to the cold level.

Checked oil..doesn't appear contaminated with coolant. Exhaust has no coolant smell.

So, anyone want to take a shot? I'm leaning toward the coolant temp sensor but not sure if it does anything other than read temp and whether it's output would effect the other symptoms.