Toller
EVERY extended parts warranty and Parts and Labor warranty that I have ever seen or sold REQUIRES regular PM to remain in force. If you have a major failure of your car and you have no PM records the warranty may be voided. Same thing with heat pumps and ACs. You probably need to check it at least once per year. Every other year would be better than nothing. Your heat & AC probably runs more than your car, you should take as much care of it as you do of your car.
Stretch