Can you take off the 2 lines going into heaTER CORE AND BLOW THEM OUT WITH A AIR LINE WILL THIS WORK?

Most likely it is the heater control valve that shifts air from blowing across your heater core to your air conditioner core.

If your fan works and your car is fairly new..meaning your heater core isn't dirty and full of craap...then it is the climate cotrol valve.
If you are lucky, it might be a thermostat that is bad and blocking hot water from entering your heater core. Bottom line, if hot water doesn't circulate thru that little heater core, you won't get heat.
You might be able to look under the hood and grab the hot water lines that go thru the firewall and feed your heater core. If they feel cold to the touch after engine has warmed up, then you aren't getting circulating water to the heater core. If they feel nice and warm, then the heater core is fine, but your climate control valve has closed off the fan that blows across the core to disperse heat into the cabin

dirty heater coil, clean it out so the hot air will travel thru

Do you smell coolant inside of the vehicle. If so then chances are your heater core is going.

need to make sure you have enough coolant and if it does then it could be your thermostate or clogged heater core

check to see if there is plenty of antifreeze in radiator , may have a air bubble in system .

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

Engines can rock on the motor mounts. You probably have a vacuum line that is pinched, cracked, broken,kinked, or unhooked. check the engine compartment lines first. If you have thin plastic vacuum lines, they can kink more easily than rubber lines. If you have been working under the dash (replacing a radio, etc) check your work area in case you have a broken fitting on a vacuum housing or an unhooked line.

You need to check the heater core it has two hoses going to it feel of them if one is hot and the other cold heater core is stopped up replace it or flush it out if they are both hot it can be the switch or a vacuum line the vacuum line will be on the passenger side under the hood where the airconditioner hoses go in the body

The problem was a vacuum line leak. Replaced the line.

You may want to check your coolant level, low coolant will not circulate to heater core. You may have a plugged heater core, if you remove the 2 heater lines under the hood these lines i think a 3/4 and go directly into the firewall on the pass side.. take them off drain the coolant and flush it out by putting a water hose to one side and let it drain out of the other line. this is a cheap way to flush a heater core. good luck hope this helps