I have a Carrier 13 SEER heat pump, model number 25HBR. I live in Alexandria, VA, a temperate climate. I clean the filters regularly and make sure the outside heat exchange coils are free of debris. The manual recommends I have ‘regular’ professional maintenance. Presumably, that’s mainly to check for leaks and refrigerant pressure. I haven’t called the company since it was installed in 2008, 6 years ago. Moreover, the heating-cooling behavior hasn’t changed noticeably over the 6 years. Should I call them to check, or are these modern heat pumps reliable enough to go 10 years or more without refilling? [If it ain’t broke, don’t fix it is my thought.]

I have to agree with you. As long as you keep the condenser coil clean and it's cooling and heating your house, I wouldn't mess with it.

If it ain't broke, don't fix it.