Heater does not work, AC and Fan do
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Heater does not work, AC and Fan do
Hi Everyone,
I'm having an issue with my electric heater. The heater will not turn on no matter how I set the thermostat, though both the AC and the fan work fine. Jumping the R and W terminals at the thermostat does nothing, while jumping them at the control board occasionally will turn the heater on, though not always. I've checked the thermostat terminals with a multimeter to make sure it's getting power to the thermostat, and the Y and G read normal at about 28v, while the W reads only 6.
I've got a Carrier FB4ANF018 and the heat unit is KFAEH0201N05.
Any thoughts on what might be happening would be appreciated.
Thanks
Ryan
I'm having an issue with my electric heater. The heater will not turn on no matter how I set the thermostat, though both the AC and the fan work fine. Jumping the R and W terminals at the thermostat does nothing, while jumping them at the control board occasionally will turn the heater on, though not always. I've checked the thermostat terminals with a multimeter to make sure it's getting power to the thermostat, and the Y and G read normal at about 28v, while the W reads only 6.
I've got a Carrier FB4ANF018 and the heat unit is KFAEH0201N05.
Any thoughts on what might be happening would be appreciated.
Thanks
Ryan
#2
Welcome to the forums.
That tells us that it's probably not a thermostat problem.
The FB4 is the air handler and the KFAEH is a dual element 5kw heater strip with relay instead of sequencer.
When you connect W to R at the air handler/furnace you should get a fairly large click from the heating relay. If you don't hear that click then you are going to need a voltmeter for testing.
Page three is your wiring diagram.
Hvacpartners docs Public FA4A-2W.pdf
while jumping them at the control board occasionally will turn the heater on,
The FB4 is the air handler and the KFAEH is a dual element 5kw heater strip with relay instead of sequencer.
When you connect W to R at the air handler/furnace you should get a fairly large click from the heating relay. If you don't hear that click then you are going to need a voltmeter for testing.
Page three is your wiring diagram.
Hvacpartners docs Public FA4A-2W.pdf
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Thanks for the reply and the diagram, that's really helpful.
I wired the red and white together at the furnace and cycled the power about five times at the breaker. The relay clicked and the fan came on each time, as long as I waited about thirty seconds after I killed the power to try again. If I didn't wait, if I just flipped the power off and then right back on, nothing happened (I think this is why it wasn't always coming on when I jumped them yesterday, as I reported in my first post).
So if it's working each time at the furnace, does that mean I DO have a thermostat issue? I don't think it's a problem with the wires, because I swapped yellow and white at both ends, and the AC worked fine using the white wire, and the heater still didn't work using yellow.
I wired the red and white together at the furnace and cycled the power about five times at the breaker. The relay clicked and the fan came on each time, as long as I waited about thirty seconds after I killed the power to try again. If I didn't wait, if I just flipped the power off and then right back on, nothing happened (I think this is why it wasn't always coming on when I jumped them yesterday, as I reported in my first post).
So if it's working each time at the furnace, does that mean I DO have a thermostat issue? I don't think it's a problem with the wires, because I swapped yellow and white at both ends, and the AC worked fine using the white wire, and the heater still didn't work using yellow.
Last edited by rbibler; 10-25-14 at 09:11 AM.
#4
Do you get heat when you connect the R, G and W wires together at the stat?
What thermostat do you have?
If you have a mercury bulb thermostat mounted above a filter grill it may only be dust preventing a good contact. I have been able to blow out the dust and brush off the subbase contacts with a dry paint brush and then seal the hole around the stat wire to correct this many times.
What thermostat do you have?
If you have a mercury bulb thermostat mounted above a filter grill it may only be dust preventing a good contact. I have been able to blow out the dust and brush off the subbase contacts with a dry paint brush and then seal the hole around the stat wire to correct this many times.
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Nope, I only get fan when I connect r, w, g at the thermostat. No heat.
I've got a honeywell mechanical thermostat. I'll try dusting it like you suggest, but it doesn't seem like that's the problem.
I've got a honeywell mechanical thermostat. I'll try dusting it like you suggest, but it doesn't seem like that's the problem.
#6
You have already proven it is not the stat.
Did you get heat when you jumpered these wires at the air handler?
5 kw isn't much heat. I would use a thermometer in the duct or a clamp meter on the high voltage wire.
http://dms.hvacpartners.com/docs/100...ag-fb4a-04.pdf
Did you get heat when you jumpered these wires at the air handler?
5 kw isn't much heat. I would use a thermometer in the duct or a clamp meter on the high voltage wire.
http://dms.hvacpartners.com/docs/100...ag-fb4a-04.pdf
Last edited by Houston204; 11-01-14 at 07:11 PM.
#7
Do you have a voltmeter and do you know how to use it ?
My feeling is that it's a defective relay for the heating elements.
The only way to test is using a meter.
My feeling is that it's a defective relay for the heating elements.
The only way to test is using a meter.
#8
I have never seen one of those 22VDC relays in a Carrier fail.
I have seen the fuse link fail or a fuse pop.
Sequencers were a different story. I would confidently say this is the most likely cause if one was present, but the pdf doesn't show one in use.
This application probably looks more like this...
I am sure that we do not have the winters that you get up north though.
I have seen the fuse link fail or a fuse pop.
Sequencers were a different story. I would confidently say this is the most likely cause if one was present, but the pdf doesn't show one in use.
This application probably looks more like this...
I am sure that we do not have the winters that you get up north though.
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Great thanks. It's definitely the sequencer, so I'll grab a new one.
Would this one work?
http://www.amazon.com/White-Rodgers-...+white+rodgers
Would this one work?
http://www.amazon.com/White-Rodgers-...+white+rodgers
#14
There are several sources listed on amazon for that part.
HN67QA005 - Aftermarket Replacement 10 KW Heat Sequencer Relay: Amazon
You would have to look up the specs for both units to see if the W/R sequencer is a viable replacement.
HN67QA005 - Aftermarket Replacement 10 KW Heat Sequencer Relay: Amazon
You would have to look up the specs for both units to see if the W/R sequencer is a viable replacement.
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The reason I asked is because the sequencer I need to replace is a SPST switch, while these Carrier replacements are DPDT. Will that make a difference? I guess I'm just not totally certain what specs I should be comparing.
Thanks again for all your help.
Thanks again for all your help.
#16
They are not double pole double throw.
The only double throw control that resembles a sequencer that I know of is a fan timer for Goodman units but they are single pole.
Carrier electric heat strips usually have a single pole double throw relay on a small control board that connects to a terminal on the sequencer.
The only double throw control that resembles a sequencer that I know of is a fan timer for Goodman units but they are single pole.
Carrier electric heat strips usually have a single pole double throw relay on a small control board that connects to a terminal on the sequencer.