Not able to deduce the HVAC repair

The other morning, our HVAC system broke down and my eager husband wanted to attempt to fix it. But I had to put my foot down; I told him that there was absolutely no way I would let him do that. I had to remind him of all the times he watched some DIY videos and completely destroyed various things we had owned. I reminded him, too, about the car that he almost destroyed when he was working to fix the engine; we had to have it towed to the nearest auto shop and the mechanic couldn’t understand the destruction he had managed to wreak on the engine! Another time he tried working on the stove when it suddenly stopped working…and he completely destroyed that. We actually ended up having to get a new stove altogether! Now with the HVAC system, this was very expensive equipment and there was pretty much no way I was going to let him touch it at all! I mean, I didn’t even let him mess with the thermostat! I called the HVAC company and luckily, they sent an HVAC corporation over within an hour’s time. When the HVAC system finally came back to life, my husband tried to tell me he could have handled that. But I told him that if he’d tried, we would have to pay for a brand new HVAC system most likely which would run us at least $7,000! Even the HVAC corporation told my husband that heating and cooling service is not as self-explanatory as it seems. He actually said that he had to study for several years to become an HVAC representative. It takes quite a bit of time and experience, not things you can pick up overnight.