Well your going to have to get a skematic of your radio, and check the connector on the back of the radio to see if you have speakers coming out of the radio, then chase a cut in the wiring or a faulty connection on the back of the radio. You said you had the heater switch recall done...maybe they accidently knocked of your speaker connection part way??? If you have no heater or AC then take it back and have them recheck it again. I suspect your radio speaker plug is not fully seated and it was knocked off when they done your blower switch. Pretty basic stuff...it is recall, so get them to see why its not working again. Your temp gage might be a faulty sending unit not giving signal to the gauge, that can be tested pretty easy as well...get yourself a manual if you intend to do your own repairs, everything your looking for and how to test things are in the book.
