I need some opinions on a problem I am having so I know where to start. I am losing coolant but their is no visible leak. My heat is cold until I start driving BUT my car does not over heat. I have filled my coolant 3x since August and filled the reservoir up 3 wks ago and checked it today and it was low low. Also, my car was all the way warmed up according to my dash gauge but it sucked NO coolant in anywhere. What could this be? Sometimes when I am sitting and I turn the heat it will blow hot for a second and then go back to cold. Please help I cant afford to replace multiple things to try to fix it. It's also winter here and it's the only car I have to get back and forth to work.