Interesting thought about the HVAC unit. A few years ago in early spring a transformer a few blocks away from my house took a direct lightning hit. Loud bang, power out for a few hours. Everything sensitive in my house is on UPS or surge suppressor, so I thought I had no problems. A few weeks later when I went to turn on my AC for the first time, it didn't work. I had someone out and he said the capacitor had failed, and based on how it looked he said it was lightning and I told him about the recent strike. He suggested I use the on/off breaker switch next to it to turn it off during the cooler months, had I done that it would have survived the strike.
The point being, if a lightning strike blocks away was able to take out my AC, anything that gets enough power running through your dish to fry the AC through the ground wire probably gets enough power running through the AC to fry it anyway!
I recently learned I've had an ungrounded dish and OTA antenna at my business for the past eight years or so, which I plan to have addressed soon. I had an installer out to replace my LNB recently and had him check out the grounding situation based on what I'd learned on dbstalk.com. He didn't have time to take care of it on that visit, but he said it would be easy to do because my dish is fairly near a couple big HVAC units mounted on the roof. I figure at least in my case, those giant pieces of metal, being on the roof, are far more attractive to lightning that my puny dish and OTA antenna. If he runs ground wires to them I'm not too worried about a strike taking one out via the ground wire that wouldn't already have taken it out anyway
SL5, PI-6S, SA-6AL 3xSWM16, 21 H20-100, 1 H20-600, 7 H24-700/AM21