A Frigidaire range can be repaired at home by its owner, if the nature of the problem is within his knowledge and abilities and is not too dangerous. To discern whether the problem is fixable by the consumer depends on a few troubleshooting steps.
If the Frigidaire range is an electric model, and the oven won't heat properly, the bake element could be faulty. That is evident by its failure to turn a dark red color when on. Bake elements are simple to replace. With the power off, unscrew the bake element and remove it. A new one can be purchased at a local appliance store and screwed back in. On a gas model, if gas burners are on, but no flame appears, there could be clogs in the holes of the gas burners or food residue on the spark plugs. If a glass cook top is broken, this can also be easily replaced by the customer.
If a Frigidaire range is a gas model and the oven fails to heat up, the problem is most likely the glow-bar igniter, and it needs to be replaced. This should be done by a professional. A technician knows how to check the whole unit for gas leaks. If an oven fails to heat up on an electric model and the bake element is not the problem, it's probably the thermostat or a selector switch. These should be replaced by a technician.