Use these tips to identify possible problems with an oil furnace.

Causes: Thermostat set too low; main switch, a circuit breaker, or fuse open; motor may be overheated.

Solutions: Set the thermostat 5 degrees higher than usual. Check switches, breakers, and fuses. Oil motor. Press reset.

Causes: Oil or spark not getting to the unit; safties sooty.

Solutions: Make sure oil valves are open and there's oil in the tank -- dip a rod into it, don't trust the gauge. Clean safeties.

Causes: Clogged blower filter or other blower problems; improperly set limit control.

Solutions: Replace filter. Oil and adjust blower. Have limit control checked and adjusted.

Causes: Combustion air blower motor needs oiling.

Solutions: Shut off the unit, let it cool, and fill the oil cups; check them again after the motor has run for an hour or so.

Causes: A cold flue causes this when the burner first fires; but if smoking persists, it's a sign of incomplete combustion, which means the unit is wasting fuel.

Solutions: Call for service. Don't attempt to adjust a burner yourself.