I have a couple Lennox heat pumps I want to have checked. Aside from gas pressure and current draw, what else would they check, or should I specifically have them check? I regularly change the filters so they shouldn't need to check those.
I could easily check the current draw with a clamp-on ammeter myself - how good is current draw an indicator of a system health?
Lastly, is it really a big deal to check line pressures? Should I get a set of gauges and Do It Myself?