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My Carrier KFCEH3101C15 air handler/electric furnace stopped working yesterday. It is a 2006 unit but it had been running very smoothly/quietly. I noticed the metal air filters were very dirty so I blew them out and replaced them. I tried to reset the system by turning the thermostat below the air temperature reading then turning off the two circuit breakers on the unit for a minute, turning them back on, then setting the thermostat to about 5 degrees above the air temperature reading. The thermostat then read "Aux Heat" as if it was trying to raise the temp in the house but the air handler never kicked on. I turned the fan switch from auto to "ON" but the fan motor did not work. It appears there is no power to the air handler/furnace. I took the access panel off and exposed the blower motor and a-coil and the blower motor felt warm to the touch. The unit has not worked for 24 hours, so either it is retaining heat or it is getting juice but not working. I can't see an obvious reset button anywhere...does anyone know what might be wrong? Could it have overheated because of the dirty air filters, and if so, why won't it reset or how can I troubleshoot and get it running again? I see a lot of wiring and a circuit board inside of the box but no reset buttons or sliders and no fuses to check except a 5amp fuse on the circuit board that looks like a fuse you would put into the panel of a car. Please help--thanks!
11/10 update: I checked all 3 limit switches (part# HH19ZA950) with an ohmmeter. I depressed and released the snap action surface of the switches a dozen or so times and each time the ohmmeter indication jumped up when I depressed the switch then dropped-off to 0.00 ohms when I released, which I believe indicates a good switch (please confirm?) One other thing; after I re-installed the switches and reset the breakers I set the temp on the thermostat to a few degrees above room temp and I could hear the blower motor humming lightly. I cycled the breakers on the furnace and could hear a switch click inside the panel. The humming indicates there is power to the blower motor, but nothing is operating. I don't know if the heater elements are heating-up because I can't see them. Thoughts?11/10 update: I checked all 3 limit switches (part# HH19ZA950) with an ohmmeter. I depressed and released the snap action surface of the switches a dozen or so times and each time the ohmmeter indication jumped up when I depressed the switch then dropped-off to 0.00 ohms when I released, which I believe indicates a good switch (please confirm?) One other thing; after I re-installed the switches and reset the breakers I set the temp on the thermostat to a few degrees above room temp and I could hear the blower motor humming lightly. I cycled the breakers on the furnace and could hear a switch click inside the panel. The humming indicates there is power to the blower motor, but nothing is operating. I don't know if the heater elements are heating-up because I can't see them. Thoughts?
Hi Cris, thanks for your reply. How do you recommend testing the run capacitor and blower motor to verify failure? I have a basic multimeter but the sources I've found say I need a multimeter with an "MFD" setting to test (I couldn't find one of those at Sears, Home Depot, or AutoZone, so I need to know if there is another way to test it). Also, the blower motor has about 8 wires running to/from it--not sure where to place the wires to test.Hi Cris, thanks for your reply. How do you recommend testing the run capacitor and blower motor to verify failure? I have a basic multimeter but the sources I've found say I need a multimeter with an "MFD" setting to test (I couldn't find one of those at Sears, Home Depot, or AutoZone, so I need to know if there is another way to test it). Also, the blower motor has about 8 wires running to/from it--not sure where to place the wires to test.
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From what your saying the motor is hot to touch if that is the case the motor is bad need to be replaced.
Testimonial: "It was just mildly warm, which might have just been because it had been running prior to the unit dying on us. Is there an easy way to check the blower motor is operational? I have a simple electrical tester but I realy don't know what I am doing with it, beyond a non-powered ohm check on the limit switches. Thanks again for any advice you can give."
Thanks for your reply, Cris. How should I test the run capacitor and blower motor? I only have a basic multimeter that can test ohms, DC ams, and voltage. The capacitor is just a standard run type with two posts on top, 4 leads per post. Since I don't have an "MFD" setting on my basic multimeter, to which setting should I set it? For the blower, there are no less than 8-9 wires...not sure where to start.Thanks for your reply, Cris. How should I test the run capacitor and blower motor? I only have a basic multimeter that can test ohms, DC ams, and voltage. The capacitor is just a standard run type with two posts on top, 4 leads per post. Since I don't have an "MFD" setting on my basic multimeter, to which setting should I set it? For the blower, there are no less than 8-9 wires...not sure where to start.
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You have one of two problems. Either the capacitor for the motor has failed or the motor has failed. I would turn off the power to the unit and see if you can locate the capacitor and remove it. An ac supply or electrical supply house can match up the capacitor. This is relatively inexpensive. Otherwise you will need a new motor.
The 5 amp fuse may be bad, they go quite often, and they are exactly the same as the car ones. Check the fuse with a meter. If its OK turn the unit on and check for voltage going to the blower fan. You should get a reading between at least one pair of wires. The unit should have a schematic on it somewhere, check it to see which wire pairs are used for the variable speeds of the fan.
Check fuses first! If yours is the model with a fuse box you will see a flap that pulls down to reveal a block of fuses, the blade fuse you described is part of it too! Are all fuses ok?
It's likely a bad tstat. Turn the power off to your air handler. Remove red , green, yellow and orange wires inside the tstat and wire nut them together. Not sure if your reversing valve energizes in heating or cooling but, turn the power back on. If the unit is heating turn the power off and remove just the orange wire and turn power back on. Let this run and see if it you are ONLY getting cool air ALL the time. If so you have a bad stat. If still getting heat possibly you have a bad control board in the air handler. Good Luck!!
Is the furnace fan (indoor fan ) running. If not the problem is with the inside unit. It supplies the control power to operate the entire system and has a control fuse on the circuit board. If it is running but not the outside unit then the problem is outside.
what is not coming on? you have to be more specific. do you have a furnace or an air handler? is your t-stat battery operated? if your indoor unit does not come on, you can have a bad low voltage transformer.
If you have a standard thermostat the fan switch is for the air handler only. It completely over rides the thermostat for most settings. Now lets see this is what I'd expect: fan switch on Indoor fan runs all time Fan switch auto Indoor fan only runs when thermostat is set to cool or heat and the thermostat is turned up above room temp for heat or below room temp for cooling. In both of these modes the furnace blower comes on and stays on til the room temperature is satisfied. The outdoor unit only comes on for AC the out door unit will not come on for heat or the "on" setting on the thermostat. See exception 1 & 2 below...
Exception 1- (in a heat pump the out door unit runs in both heat and cool mode
unless it has emergency heat turned on then it will not come on outside
in the heat mode, and depending on the type of heat pump and furnace or
air handler it is). A heat pump thermostat usually has "backup heat" and an "emergency heat" setting switch on the thermostat. Exception 2 - On some thermostats they are made to cycle on the heat if the temperature reaches a preset temp (around 50'f usually but definitely by 40'f). This mode prevents freezing when if instance the homeowner is away or while the home is under construction. In this mode the fan inside can run but the heat usually comes on with it. Exception3 - On some electric furnaces the heating strips may be individually controlled and thus not all come on at one time. This may give the feel of no heat especially if the room is cold.
Now there may be other exceptions but Ive tried to give you a heads up on some of the most common ones. If you need more help please post more specifics about your unit/system as to for sure what switches are set to what setting and what is happening with each. My first though was that maybe your system is OK and you needed to know if the thermostat was working properly.
If this helpd you understand your problem would you please give me as hifgh a mark as you can. Thnaks for using fixya and good luck.
Hi!!! Does your ac unit work fine?If not check your low voltage problem..You have a low voltage problem check the wire going out to your condensor make sure that they are not touching..Good luck..Check low voltage wires..short in progress..
11/10 update: I checked all 3 limit switches (part# HH19ZA950) with an ohmmeter. I depressed and released the snap action surface of the switches a dozen or so times and each time the ohmmeter indication jumped up when I depressed the switch then dropped-off to 0.00 ohms when I released, which I believe indicates a good switch (please confirm?) One other thing; after I re-installed the switches and reset the breakers I set the temp on the thermostat to a few degrees above room temp and I could hear the blower motor humming lightly. I cycled the breakers on the furnace and could hear a switch click inside the panel. The humming indicates there is power to the blower motor, but nothing is operating. I don't know if the heater elements are heating-up because I can't see them. Thoughts?
Hi Cris, thanks for your reply. How do you recommend testing the run capacitor and blower motor to verify failure? I have a basic multimeter but the sources I've found say I need a multimeter with an "MFD" setting to test (I couldn't find one of those at Sears, Home Depot, or AutoZone, so I need to know if there is another way to test it). Also, the blower motor has about 8 wires running to/from it--not sure where to place the wires to test.
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