Ty for having this site-it is very helpful-my question is I called a service tech my fuse 5 amp kept blowing-he said the reversing valve and the board were bad-how could I have checked this myself-it is a payne ac unit-he said he had to disconnect low voltage to condensing unit in order to get the emergency heat going-i don't understand why having to disconnect low voltage outside would affect the emergency heat.

By killing the unit outside it will probably not blow the fuse which will allow the 24 volt circuit to keep operating so you can have emergency resistance heat.

Usually heat pumps are more complex than standard A/C units so for a home owner to be able to check it out the would almost have to go to school to learn all that is needed to fix it. Also many special tools are needed that you may not have so it is expensive for you to service your unit. Sorry but that is the way it is.

Is there a trouble shooting book available which would help me better understand heat pumps as I know about standard ac units-heat pump is something new I'm working with all your help is greatly appreciated

There are many different books available. Use Google search engine to find them