I checked with my nephew, who used to be in HVAC. Here's what he said:
Typical day is getting your assignment/job for the day and then making sure you have all the supplies you'll need on the van. Going to the site of the job and performing whatever was asked - usually a repair service or an installation of HVAC equipment.
He thought the best part of the job was seeing your hard work pay off with a great looking install. Or solving an issue after performing a lot of troubleshooting and making the repair on a furnace or air conditioning until.
Your last question was harder for him to answer, because he said every day is a new adventure and a new challenge to overcome. But I would suggest that in whatever field you pursue, your personal brand and communication skills will really make a difference. People will always remember how you made them feel, and you'll be introduced to new people on a daily basis.
I hope this helps and I wish you the best Jose!