My unit (nordyne e1eb-015ha) will not stop heating.have to use breaker.which switch(s) or relay should I change and where is the best place to find them.I live I Birmingham,Alabama.ive change the thermostat and on/auto swith also.when I set it to cool the cooling unit comes on but the heat remains on and the unit still blows hot HELP!I can change it/them just can't trouble shoot... thanks ahead of time