The upper limit switch on my Coleman furnace will not close.

IF YOU LOST POWER WHEN FURNACE WAS RUNNING IT TRIPPED ROLLOUT SWITCHES AND POSSIBLY THE HIGH LIMIT . IN CENTER OF ROLLOUT SWITCHES IS A LITTLE RED BUTTON THAT YOU RESET . YOU CAN ALSO TRY FINDING HIGH LIMIT WITH POWER SHUT OFF TO FURNACE PULL BOTH WIRES OFF HIGH LIMIT AND USE PAPER CLIP TO JUMP BETWEEN THE TWO WIRES MAKE SURE YOU DONT SHORT OUT AGAINST ANY METAL WHEN YOU TURN BACK ON IF IT WORKS YOU NEED A NEW HIGH LIMIT SWITCH.

Limit switches are safeties and require a manual reset. They are also a Normally Closed contact. A hi temp. thermostat operates on its own. If you are sure it is a limit, find the red little button and listen for it to click. Sometimes they push pretty hard.

Blower motor is bad or going bad

Hey, nofarmark91

Turn the Coleman furnace system switch to the "Off" position on the electric service panel.

Locate the manual reset switch near the left side of your furnace blower. Your Coleman furnace has an upper limit switch for manual reset and a lower limit switch for automatic reset.

Press the reset button, which you will find in the middle of the limit switch. Use this manual reset button when the furnace burner will not operate. (See Reference 1 pg 4 "The Furnace Controls and their Function/Important" & Reference 4 # 3)

Turn the system switch to the "On" position.

Good Luck

i hope the heater doesnt come on when a limit switch is open,you really have problems. so a limit is telling you that your furnace it over heating. first check filter and heat vents and returns they must be clean and open. closing heat vent or blocked returns will cause over heating. after chacking this look at firing rate. furnace could be overfired. you would need a "u" gauge to check manifold pressure. your name plate will tell you what this should be. find the tap on the burner manifold or outlet of gas valve. fire furnace and see what it is. 3.5"wc for nat and 10" wc for propane maybe.

How do you test a pressure switch and other limit controls?
This is for people who are experienced with electrical equipment and the use of a Volt Ohm meter. *Please never by pass a pressure switch or limit control. The pressure switch and limit switches are there for your safety. You would test by setting your volt meter to "Volts AC" and test the rollout switch by placing one meter probe on one terminal of the rollout switch and your other meter probe to a good ground. Have the red probe touching the top terminal of the rollout switch and the black probe touching a ground (body) of the furnace. You should be getting 25.85 volts which means the rollout is good on the top terminal. I would next test the bottom terminal of the rollout by touching the red meter probe to the bottom terminal on the rollout switch and the black terminal to ground. If I get 25.85 volts on the bottom terminal the rollout is good. If I do not get any voltage on the bottom terminal then the rollout has tripped and can be reset (if equipped) by pressing in on the little button or replaced. If your rollout switch is tripped you probably have a stopped up heat exchanger or a leaking heat exchanger. I would recommend calling in a service technician to find out why the rollout switch tripped. If you have an open limit control either the furnace has over heated or the limit has gone bad. Problems that would make a limit open up would be dirty filters, dirty evaporator coil causing a restriction in the air flow or a slow blower motor (check the capacitor on the blower motor to make sure it is good). A weak blower motor capacitor will cause the blower to run slow and eventually fail. Pressure switches, and limit switches can be tested with a meter in the same manner. With the furnace calling for heat you can test each of the terminals on the pressure switch to ground to make sure the pressure switch is closed. You should be getting between 24 to 28 volts from each terminal to ground if the pressure switch is closed. If the pressure switch is open you either have a stopped up vent, drain line (if you have a condensing furnace) or bad pressure switch.

you have multiple stages of heating and not all of the stages are operating. it could be a limit switch, that would be a very good place to start.(stages or zones)

Hi,
The chances are that the furnace was running when the power went out. This will cause the high limit switch to cutout and needs to be manually reset.
You will find that switch in the blower compartment near the blower. Usually somewher near the highest point of the cabinet.
Push the little red button firmly till it clicks.
When the power goes out while the furnace is running the heat builds up because the blower shuts down immediately and causes this limit switch to cut out.
If you have a electric tester you can also follow the low voltage circuit till you find the open switch. Ther is usually a wiring schematic on the door cover of most furnaces.

I hope that this will help you to solve your problem!

Thanks for using Fixya!!

Heatman101

If the fan takes too long to come on, the high temp limit may be opening. Could be a defective limit, hard to say without more info. Another possibility is a mis-adjusted heat anticipator. A normal setting would be around .45 amp. The heat anticipator is inside the cover of the thermostat (older, analog style). Good luck.

safety limit switch,or some people call them a firestat,it has a red reset button in the middle,located in the return with two wires connected to it,detects heat