There you are, enjoying a good movie late in the evening, when you realize you’re shivering. You go to turn up the thermostat, but nothing happens. You tap on the thermostat, maybe blow on it, hoping that’ll make the system kick on, but when it doesn’t, your heart sinks, and you realize that your furnace has gone kaput, leaving you in a real bind. It’s cold outside, and morning is a long ways off. So what do you do?

Troubleshoot the Problem

There’s a chance that the problem is an easy fix, so the first order of business is to do some troubleshooting.

First, make sure you’ve got the thermostat set to “heat,” then turn it up to 90 degrees. If nothing happens, check to see if the thermostat requires batteries. If so, change the batteries. If not, leave the thermostat set to where it is and head off to check the furnace filter. A clogged filter can cause the system to overheat and shut down, but replacing the filter should take care of the problem.

If the problem isn’t with the thermostat or the filter, it may be electrical. To check, flip the thermostat’s fan switch to ON. If the fan kicks on, the furnace is getting power. If it doesn’t kick on, check the circuit breaker associated with the furnace. If it’s intact, find the power switch on the furnace itself–it probably looks like a light switch–or on a nearby wall. If the switch is off, turn it on and wait a few minutes.

If your furnace is ancient, as in 20 years or older, check the pilot light. If it’s off, refer to your owner’s manual (if you can find it!) and re-light it.

Call for Service

If nothing you try works to get your heat back on, it’s time to call for service. According to Home Advisor, the average cost of a furnace repair is $258, but if you call for 24/7 emergency heater service, you can probably expect to pay a bit more than average.

Use your best judgment when deciding whether to call for emergency service on a Sunday morning or wait it out until Monday morning, when you’ll pay less. It will all depend, of course, on how cold it is outside and whether you’re prepared to “chill out” until a repair can be scheduled during normal business hours.

Prevent Future Problems

Belknap Heating and Cooling, an HVAC contractor in Buffalo NY, estimates that 80 percent of their after-hours emergency calls could have been avoided by scheduling regular furnace maintenance at the beginning of the heating season.

Annual furnace maintenance is recommended by the Department of Energy and almost every HVAC contractor in the country, because an inexpensive tune-up in early fall has been shown to lower heating costs, improve comfort, extend the operating life of your furnace, and reduce harmful carbon emissions. So when you schedule your repair, ask about having your furnace tuned up at the same time. Your technician will clean the system, check wires and connections, and perform a number of safety and operating tests to help ensure your system functions optimally for the remainder of the winter.