Heater does not work, AC and Fan do


  #1  
Old 10-24-14, 03:34 PM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
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
 
  #2  
Old 10-24-14, 04:23 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,929
Received 3,950 Upvotes on 3,543 Posts
Welcome to the forums.

while jumping them at the control board occasionally will turn the heater on,
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
 
  #3  
Old 10-25-14, 08:50 AM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
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.
 

Last edited by rbibler; 10-25-14 at 09:11 AM.
  #4  
Old 10-31-14, 06:54 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
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.
 
  #5  
Old 11-01-14, 09:36 AM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
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.
 
  #6  
Old 11-01-14, 06:51 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
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
 

Last edited by Houston204; 11-01-14 at 07:11 PM.
  #7  
Old 11-01-14, 06:59 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,929
Received 3,950 Upvotes on 3,543 Posts
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.
 
  #8  
Old 11-01-14, 07:53 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
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.
 
  #9  
Old 11-02-14, 09:14 AM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
So it looks like I have 28VAC at the orange and violet wires coming into the sequencer, but 0 at the yellow and black wires on the heating strip.
 
  #10  
Old 11-02-14, 02:06 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
Do you have a sequencer in your heat strip?

 
  #11  
Old 11-02-14, 07:05 PM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
Yeah, a Therm-o-disc 15sh1 309581.
 
  #12  
Old 11-02-14, 09:06 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
  #13  
Old 11-07-14, 01:12 PM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
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
 
  #14  
Old 11-07-14, 08:56 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,929
Received 3,950 Upvotes on 3,543 Posts
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.
 
  #15  
Old 11-08-14, 08:22 AM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
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.
 
  #16  
Old 11-08-14, 01:37 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
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.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: