2005 Eguionox chevy

What is your question?

I have a 2005 equionox Chevy When I am sitting and ideling the car loses heat and goes to cold air if I rev it up to about 1500 rpm it will start getting warm and throw out good heat but let off the gas and it gets cold again

How long has your 2005 Chevrolet Equinox had this problem?

Since i bought it a few weeks ago.