being as having been in your situation I went the hvac route all most 20 years ago still work air planes full time but do the hvac on the side can make good money at it but I can tell you that hotels and office bldgs are not were you can do that. installs (retro and new) are not either at least for the tech unless your union and a journey man. I talked to a gut in fla a few years ago was working for a service co and with 16 years exp was making 16.50 an hour I was making 21.00 here in stlouis at the time just some comps. Good service techs are had to find so all i can say is learn your theory and how to read wire diagrams plus a good helping of ESP helps cause you have to read the mind of the guy (person) the last did work on it! cant tell you how many times i have asked myself wtf were they thinking? oh and if the wallet can afford go with c if not witch ever will get you making money the fastest