1-No heat or low heat
Have they checked filters (plugged)?
Have they checked fuses/circuit breaker?
What is thermostat set at?
It is easy to forget to switch to heat or turn up setting
2-No fan or runs continuous
T-stat set to fan “on” not auto
3-How often to replace Aprilaire media type air cleaner filter depends on the house. For example dirt
basement windows open in summer, allergies-(These conditions would tell you to replace it 6 months to 1
4-Your house is closed mainly year round-you have central air, no allergies-(these conditions would tell you
to replace it 1-2 years)
All other types of filters-should be replaced every 1-3 months