we installed a mitsubishi split system mxz-4b36na. the a/c worked great in the summer but now we turned on the heater and it is blowing cold air instead of warm. we turned on the 4 inside units and it is the same problem. it is not blowing warm air. what could be the problem?
Need make sure its hook up right and the reversing valve is shifting. I work on that kind unit all the time and did find reversing valves are bad. Matter fact the supply house were we get parts from say that recall had been sent out for those units.