You really should fill upp the radiator from the cap! If your car doesn't give warm air into cockpit anymore then you don't have much coolant left (just for information). If you haven't previously followed radiator fluid level then now is the time because there might be some reason why fluids are disappearing from the radiator. If this happens in the future too then post up here and we'll think together what migth cause it. 
- No-Pain -
- No-Pain -
