When your furnace fails to operate properly, it can present a serious problem. If it happens during dangerously cold weather, you may have to find alternative housing to stay safe. Here are some common furnace repair problems, along with some procedures to follow to find the source.

If the problem involves a minor furnace repair, the cost of doing it yourself can be a lot less than hiring a professional furnace repair technician. If you follow a few recommendations, you may be able to do a simple furnace repair. Each of these procedures will work on a home heating system, as well RV furnace repair issues.

Common Furnace Problems

As you follow each of these steps to check for common furnace problems, be mindful they become progressively more serious. If you are not sure of what to do at any juncture, the best advice is to schedule an appointment with a professional technician. However, many of these common problems are simple fixes that will cost you little or nothing, if you follow the correct procedure.

#1. No Power Source or Faulty Transfer

The most common problem with a furnace is logically no heat. Not to doubt anyone’s common sense, but the first thing to do is check to see if the thermostat is turned on properly. Sometimes, inadvertently, of course, the switch is in the wrong position. This is the easiest fix of all if that turns out to be the problem.

First, check if the thermostat on the wall is set to heat and the temperature setting on automatic. If it still does not turn on, you could have a problem with the source of power to your furnace. This might also be a zero cost, a simple correction. What you do next depends on the source of power.

#2. Gas Heating

a lennox furnace machine

a. Gas Off

If you are on a natural gas external feed, check the valve of the heater. Be sure you know what you’re doing. If you have any doubts about what is on, and what is off, check with a professional. You can make notes of what is correct, but do not attempt to guess. If the valve of the heater is off, simply turn it on. Follow instructions to light the pilot if it is not automatic.

b. Pilot Off

If the pilot light goes out on your furnace, it will not fire. It will appear that you have no heat, when in fact, all that’s missing is a source of heat. There is nothing wrong with your furnace, and this is another free fix. In the same respects as turning on the gas source, if you have questions about lighting a pilot light on a furnace, consult a professional first. The consequences of a mistake may not be pleasant.

c. Electric Off

Even if you have a gas boiler, if the electrical power source is off, you will have no heat coming through your ducts. The furnace will have the fuel to produce heat, but will not activate the blowers. This could be nothing more than a tripped breaker. Check the breaker for your furnace first.

Procedure & Cost

If the breaker is on, but you still have no air coming through your ducts, the relay could be bad. This can be as simple as buying a new relay and installing it yourself. However, in the same way messing with gas without experience is dangerous, it is not advisable to attempt electrical repairs if you do not know what you’re doing.

Consult with a professional for a reliable advice. A service call and replacement relay switch shouldn’t cost you more than $60. That’s a lot less than replacing an entire circuit if you blow your furnace’s fan system.

#3. Electric Heating

The same furnace repair procedures apply if you have an electric heating system. Check the thermostat settings, but then you move directly to the breaker box. If all the sources of power seem in order, the most common problem with electric heating is the fan going bad.

You will notice a very faint feel of warm air coming from your ducts, but it will not be sufficient to move heat through your house. If you do not hear a fan, either there is a wiring problem, or the fan is shot. Unfortunately, it’s recommended that you call a professional technician to make the final determination.

#4. Bad Thermostat

the inside of a furnace machine

Once you are confident the power source to your furnace is working, next step is to go back to the thermostat. Frequently, thermostats will read like everything is okay, but they will no longer be sending accurate information to your furnace. If that’s the case, your thermostat is bad. Not a difficult fix if you follow a few simple instructions.

Changing out a thermostat yourself is going to save you quite a bit of money. Service calls by heating and air conditioning professionals are usually reasonable, often with a free estimate. However, when they begin to replace things, the costs increase. Thermostat replacement is no different.

Costs Involved in Repairing a Malfunctioning Thermostat

First, you need to decide how elaborate you want the thermostat to be. You can replace your old one with a comparable model, or add things like programmable features. A basic thermostat will cost around $25 to $50. Programmable models run as high as $200, but these have a number of energy saving features. Hiring a professional furnace repair service to do the job can cost as much as $450 to replace a thermostat.

How to Replace a Bad Thermostat

1. Shut Off the Electric Power

To replace your thermostat, you’ll need to access the breaker box again. The first thing you need to do is shut off the electric power to the furnace. This is the same procedure for both gas and electric furnace repair. There is no need to turn off the gas to a gas furnace when changing the thermostat.

2. Take the Front Part Off

Take the face off the old thermostat and look for clips underneath that attach the front to the back plate. Usually, a standard screwdriver will pop the face off without much difficulty. You will then see the wires exposed. A good suggestion is to write down which wires match to what points on the old thermostat. Better yet, take a picture with your phone.

3. Carefully Unhook the Thermostat’s Wires

Unhook these wires carefully. The old thermostat should be set aside, just in case you run into any problems with the new one adapting. If you do, take your old one to a home repair store, and they will be able to find a correct model. Most models will fit any system, but there are some unique situations where they will not. Be on the safe side and keep the old thermostat.

4. Follow All the Required Instructions for the New Thermostat’s Installation

Review all the instructions completely for your new thermostat. The procedure is usually fairly simple, but it is good to get a complete overview before you begin. Follow the instructions for attaching the correct color wire to the right spot on the new thermostat. When all the wires are affixed properly, mount the new back of the thermostat to the wall.

5. Put the Cover Back

Before you go through the trouble of putting the cover back on, flip your breaker back on to make certain the new one thermostat is wired up correctly. If all is in order, flip the heat on switch, and you should feel the warmth through your ducts in a few moments. Snap the face cover back on, and your new thermostat is ready to go.

Let’s Recap

If you’ve checked all the potential power source problems and installed a new thermostat, but you still have no heat, you may have a more serious problem. Furnace repairs beyond these common problems can become involved. While furnace repair companies specialize in technical repairs, you can handle these without much difficulty.

If you are not trained in furnace service repair, you could cause more problems, or worst of all, injury yourself. Beyond checking these basic potential issues, any involved furnace repair should be undertaken by a licensed technician.

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