Why is the heat blowing cold. i already put antifreeze and it turns hot for a couple days then its cold again

sounds like you need more antifreeze , make sure fluid is at proper line on overflow tank

LET YOUR CAR WARM UP FIRST!! or you risk the chance of over heating and casuing engine damage. start your car let it warm up for 5 to ten minutes and then try the heat. also when you start you should NEVER have heat on right away. the heat that you feel comes from the engine. and if the engine is cold and you are trying to heat it up it will put stress on the engine and over heat. ALL cars have to wait for their heat. that's why you see peoples car running in the morning with no one in it. so when they do get in it they have heat. heat will not work until the engine is warm.

its VERY likely that your heater core is getting stopped up.

The heater in your car works by circulating hot water from the engine into a copper or aluminum pipe coiled up in the dashboard. The heater/airconditioner's fan blows across it and the hot air comes out of the vents. This is why the heater doesn't work right away when you first start the car. It usually won't work until the hot/cold needle in the gauges is starting to rise up.

If your mechanic recently replaced the thermostat, its possible that there is air in the system which will result in less antifreeze in the car than it should be. If this is not the case, the heater core is probably stopping up and will require expensive replacement if it cannot be flushed clean.

Check to make sure the car is full of antifreeze IN THE RADIATOR, AND THE OVERFLOW JUG. Please be very sure there is NO AIR in the cooling system as well.

Scott

sounds like your heater core

Possible heater core poss. thermostat ck. both heater hoses at fire wall 1 hot 1 cold its the core ck pass side floor wet its the core Maybe head gasket

Try flushing or blowing high pressure air through the heater core lines. its sludge build up and need to be flushed through heater core only. check antifreeze fluid level. only put in straight antifreeze, do not mix. most people do not know what mixture should be, so be safe and add straight, it will not hurt it, i run 100% straight antifreeze and never had a problem or worry about it ever freezing and cracking my block, heads or radiator cracking.

To troubleshoot this types of problem,click the link below :----http://howtobyme.blogspot.in/2012/02/heater-blows-only-from-defrost.html
--------Go through the procedure to confirm the issue.

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Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

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Heat blows cold on drivers side and hot on passenger side?

http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html

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This will help.Thanks.

sounds like its down to the last resort ,drain antifreeze then refill with cold water and add about 300grms of caustic soda ,drive around for a day or so then as soon as heater starts to work ,flush the cooling system PROPERLY then re add your antifreeze and away you go with a nice warm car

might just be a bad engine coolant temp sensor , it tells car computer engine temperature and computer controls fans , as for recharging a/c , did you pull system under vacuum ? to check for leaks ? vacuum also helps remove air to get a better charge because air expands

overheating is most likely a bad thermostat, but the coolant loss is a second big concern. Does the exhaust look like steam? You could have a cracked block and the coolant is leaking into the engine. Also check the oil for contamination.