Hi and welcome to Coleman HVAC Part Store Helpful tips. Each year we see a high number of electric furnace fails in the fall and I wanted to put together some helpful tips so you can better understand your electric furnace.
The sequencer is the main brain in operating the electric heat elements in your furnace the sequencer is a series of switches that turn on the heating elements in a sequence one at a time in 30 sec intervals. the sequencer operates with very small heating elements inside them so when the low voltage (24V) from the thermostat comes on it heats up a very small coil under the switch until it makes contact and turns on high voltage heating element #1 then about 30 seconds it will turn on element #2 and then about 30 seconds it will turn on element #3 and so on.
As the sequencer gets old they don't perform well as they have small internal parts that wear out. sometimes the switches stick and can keep the elements on all the time or they dont come on at all and the house has minimal heat.
The best way to inspect the function of the sequencer is with a voltage meter. when you turn the thermostat up and make a call for heat you will hear a CLICK take the voltage meter and check the voltage on the heating elements to make sure your getting high voltage on the heating element OR check to see if the heating elements a glowing orange like an electric oven range. If any signs of non operating sequencer replace it as small problems become bigger problems as time goes on.
REPLACMENT - Sequencers are fairly easy to replace, With all the power disconnected I take one wire off at a time starting at the bottom and put it back on the new sequencer in the same spot most sequencers are spade terminals so they just unplug from one and plug in to the new one. The very bottom wires are your low voltage (24VAC) and the element wires are (240VAC) the very top of the sequencer M1 - M2 are to control the fan blower unit.
When inspecting your furnace look for any burnt wires and replace them!!, The normal cause for burnt wires are loose terminals! All electrical connections must be tight so they do not cause conductive heating from loose contacts.
TIP: If you live out in the boonies I would suggest to keep a sequencer on the shelf as a spare, there is no shelf life and it might save a frozen house in the middle of a blizzard.
Electric furnace with no sequencer??? Yes some of the older models have contactors works the same way just no sequence ON or OFF and other furnaces might have a relay but sequencers are the most popular. Look at your parts breakdown to know what sequencer part number your furnace needs as sequencers come in many styles and sizes.
Before you change your sequencer go to Youtube and watch some videos I have found it very helpful to watch the process before the job just as a refresher and to give confidence, If you get stuck along the way just give us a call and one of our technicians will help you with your problem.
If your sequencer is operating normal but your fan turns on and off during the heating cycle then check for the blower motor getting hot and tripping out on thermal overload or a faulty / weak fan limit switch.
As a reminder here at Coleman HVAC we have all the parts you need to keep your electric furnace operating for years!
HINTS: Normal life of a sequencer is 7 to 10 years, OEM is good but an aftermarket part is just as good and they normally have 1 year warranty anyway. TURN OFF POWER when not in heating season, I have had so many calls over the years of high electric bills or the air conditioner not putting out cold air and its because of a faulty sequencer making the high voltage stay on to one or more heating elements.
Thanks for reading if you have any questions or need technical help just email us. email@example.com