Heater/AC problem. Hot air barely warm & cold air barely cool. Fan is OK I think.

What is your question?

I've had a problem with the heater and air conditioner for the last two seasons. Both systems are weak, meaning that the heater barely puts out warm air and the AC system barely puts out cool air. The fan seems to work fine. I was told the problem is the motor, but I'm not confident about that. Does anyone have information about this problem?