Reinstall the access panel and disconnect block. Turn on the circuit breaker and furnace switch. Then set the thermostat to a lower temperature and wait for the AC to start (see “Be Patient at Startup,” below). The compressor should run and the condenser fan should spin. If the compressor starts but the fan doesn’t, the fan motor is most likely shot. Shut off the power and remove the screws around the condenser cover. Lift the cover and remove the fan blade and motor (photo 7). Reinstall the blade and secure the cover. Then repower the unit and see if the fan starts. If it doesn’t, you’ve given it your best shot—it’s time to call a pro.
If the power to the heat pump goes out, be aware that most heat pumps have auxiliary heating elements that provide heat when the weather gets really cold and the heat pump’s efficiency drops too low. These elements automatically turn on at a fairly low temperature—around 20 degrees F. When they come on, they may be drawing too much power, which can trip the circuit breaker. Just locate the circuit breaker that serves the heat pump and reset it.
Restoring or replacing an aging unit can get expensive. Invest in a new model if your utility bills are rising and you notice uneven air flow and temperatures throughout your property. If one room is cooler than another, consider a total replacement. If the air conditioner is relatively new and still within its age range, it's more cost-effective to get a contractor to repair it.