Fan Sticking on and Aux Heat not Working

Reply

  #1  
Old 12-30-14, 09:57 AM
R
Member
Thread Starter
Join Date: Apr 2014
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
Fan Sticking on and Aux Heat not Working

Occasionally the fan will stick on in my air handler, and the auxiliary heat will not work. When this happens, it stays that way until I power cycle the air handler. Hereinafter I will call this the "problem mode".

*I have tried removing the green wire from the control board while the air handler is in the problem mode, even though the thermostat isn't calling for fan, and the fan continues to run.

*I have replaced the control board 3 times. The control board houses the fan relay, and 1 of the 3 aux coil relays.

*I have tested the other 2 relays separate from the control board, which control the remaining 2 aux coils.

*I have measured the ohms of all 3 aux coils, and they all measure 11.1.

*I have replaced the thermal limit switch.

*I have shorted across (basically bypassed) the thermal limit switch while the air handler is in the problem mode, and there is no change. This should mean the new thermal limit switch is working properly.

*I have disconnected the thermal limit switch (so the circuit is open), and then powered on the air handler. The fan instantly turns on. This is functioning as expected.

*There is a 30 amp circuit with the control board, fan, and 1 aux coil on it, and a 60 amp circuit with the 2 other aux coils. With 2 aux coils on (while not in the problem mode of course), the 30 amp circuit measures 23 amps, and the 60 amp circuit measures 21 amps. With all 3 aux coils on, the 60 amp circuit measures 42 amps. This all seems correct.

*The more the aux heat is used (cold winter days), the quicker the problem mode reappears. It's almost guaranteed to be in the problem mode when I wake up after a cold night (30 degrees or less). In warmer weather, it can go 3 or 4 days before problem mode is activated.

*After a fresh power cycle, I have made a heating call including aux heat. The aux heat relays all click on properly. After a bit, the relays click off, and back on and so forth. The thermal limit switch is doing it's job. I ended the heating call. Everything shut down properly including the fan. This verifies using aux heat does not necessarily trigger the problem mode. It also verifies the thermal limit switch being activated does not necessarily trigger the problem mode.

The system:
Air Handler- York N1AHB1206A
Aux Heater- York 2HK16501506
Evaporator- York G2FD036H17A
Heat Pump- Goodman CPLE36-1

What could possibly be wrong? I am out of ideas.
 
Sponsored Links
  #2  
Old 12-30-14, 11:14 AM
firedawgsatx's Avatar
Member
Join Date: Jul 2013
Location: USA
Posts: 1,727
Received 0 Votes on 0 Posts
Based on the symptoms you describe it sounds like the control board is causing the problems. As shown in the attached diagram all functions are pretty much controlled by the board. Here are links to an installation manual and parts manuals for your air handler in case you don't have them:

http://www.upgnet.com/PdfFileRedirec...002-B-0704.pdf
http://www.master.ca/documents/0NAHRepairParts-0303.pdf
 
Attached Images  
  #3  
Old 12-30-14, 11:26 AM
R
Member
Thread Starter
Join Date: Apr 2014
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
That's what I had thought also, but like I mentioned, I have tried 3 different control boards. They all do the same thing. Is it common practice to not bother connecting Y and O wires at the control board, as they are solely heat pump controls? They are currently connected, but I have heard some people say not to. Looking at the board, the O connection does absolutely nothing, and Y does do something. I'm guessing Y does the fan delay when Y and G are de-energized.
 
  #4  
Old 12-30-14, 03:04 PM
firedawgsatx's Avatar
Member
Join Date: Jul 2013
Location: USA
Posts: 1,727
Received 0 Votes on 0 Posts
I have tried 3 different control boards.
Are the replacement boards oem?

Is it common practice to not bother connecting Y and O wires at the control board, as they are solely heat pump controls?
The installation manual shows the wiring connected to the Y and O terminals. Always a good practice to follow the manual.

Looking at the board, the O connection does absolutely nothing, and Y does do something. I'm guessing Y does the fan delay when Y and G are de-energized.
The O terminal energizes the reversing valve at the heat pump. A Ruud unit energizes the reversing valve in heat mode. The Y terminal sends 24V to one side of the heat pump contactor's coil.
 
  #5  
Old 12-30-14, 03:26 PM
R
Member
Thread Starter
Join Date: Apr 2014
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
I don't know if they are OEM, but all I was able to find by Googling 031-01264-002 was one by the same manufacturer, available from many sources. On the board it says Source 1 HVAC Service Parts. 1139-83-7002 REV. A.

In the following thread someone mentioned not to connect O and Y at the air handler, which is why I asked. My heat pump is not a York like the rest of the system.

I was referring to what O and Y do at the control board. O does nothing (other than creating a means to tie thermostat and heat pump O wires together). Y does have a trace on the board for something. I do understand O and Y's role at the heat pump.

I believe when I purchased the home 8 years ago, O and Y were NOT connected to the control board, but rather wire nutted directly to the heat pump. I suppose it's worth a shot reverting it to this, just to see if the problem goes away.
 
  #6  
Old 12-30-14, 03:32 PM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Location: USA
Posts: 4,629
Received 57 Votes on 53 Posts
How long has this been happening ,what has changed? Normally the thermal limit will shut the the unit down from over temp ie. dirty filter etc. why did you replace it?
Geo
 
  #7  
Old 12-30-14, 03:45 PM
R
Member
Thread Starter
Join Date: Apr 2014
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
It probably started last summer. It's hard to say when. It would have been less noticeable back then because the fan ran a lot for A/C, and aux heat was never used. I replaced the thermal limit switch a few weeks ago to see if that would fix the problem, as a bad switch that would stay "open" would cause the fan to continue to run and aux heat not to work.

Last April or May I had gone through and cleaned up the wiring (wrong colors used, defrost mode not connected, etc.). That is when I connected Y and O at the air handler control board, per the manual.
 
  #8  
Old 12-30-14, 04:16 PM
firedawgsatx's Avatar
Member
Join Date: Jul 2013
Location: USA
Posts: 1,727
Received 0 Votes on 0 Posts
I suggest you check all wiring terminals to make sure there is no corrosion and all wires are fully seated.

On the board it says Source 1 HVAC Service Parts. 1139-83-7002 REV. A.
That appears to be the correct part number.

I was referring to what O and Y do at the control board. O does nothing (other than creating a means to tie thermostat and heat pump O wires together). Y does have a trace on the board for something. I do understand O and Y's role at the heat pump.
It makes for a neater installation than wire-nutting the low voltage wires together.

I suppose it's worth a shot reverting it to this, just to see if the problem goes away.
I honestly don't think it has anything to do with your issue.
 
  #9  
Old 12-30-14, 04:53 PM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Location: USA
Posts: 4,629
Received 57 Votes on 53 Posts
Is there a readable wiring Dia?what model Tstat are you using? I see in the T/S guide why you considered the Thermal limit,my mistake.
Geo
 
  #10  
Old 12-31-14, 09:44 AM
R
Member
Thread Starter
Join Date: Apr 2014
Location: USA
Posts: 8
Received 0 Votes on 0 Posts
Just to rule it out, I wire nutted Y and O, instead of connecting them to the control board. It went into the problem mode within a couple hours, so it's not that.

Next, I removed the W wire from the heat pump, so defrost mode won't trigger aux heat. I also changed it so aux heat from the thermostat is only stage 1 electric heat, which uses 1 of the 3 coils. It ran all night this way, and in the morning, it was still functioning properly. No problem mode!

I have developed a new theory. In the manual it mentions something about aux heat being disabled (and probably fan enabled) for 1 hour when the thermal limit switch is tripped 4 times. My theory is the 1 hour part is not working correctly, and is ending up being indefinitely, due to a faulty control board design. This theory fits with every detail I have mentioned so far. Thoughts?
 
  #11  
Old 01-19-15, 02:10 PM
D
Member
Join Date: Jan 2015
Location: usa
Posts: 3
Received 0 Votes on 0 Posts
I am having the same problem. I am on my third control board they last about 2 months than the fan stays on, killing the power resets the problem for a few days.
A few years ago the house was hit by lightning and the board in the air handler was knocked out the repairman did not screw the board down so when I replaced it I didn't either now I am thinking that the ground might be needed to drain the static on the board. Will properly secure the board this time and see what happens.
 
  #12  
Old 01-20-15, 01:06 PM
D
Member
Join Date: Jan 2015
Location: usa
Posts: 3
Received 0 Votes on 0 Posts
After seeing your problem on the net and realizing I had the same problem I got to thinking, what changed to start this? Than it dawned on me I had asked a professional heating and cooling guy what low temp he locked out the heat pump at. He said leave it going all the time and you will get a little heat out of it. I changed the programing on my thermostat to no compressor lock out. When the conditions are just right temp wise it can keep looking for heat outside and not switch to aux heat. On my thermostat, a Honeywell TH8320U it is option 0350 and 0360. changed it last night and so far it is working properly.
I think this can only happen if you have a programmable thermostat and an outside thermometer on it.
 
  #13  
Old 02-16-15, 07:15 PM
S
Member
Join Date: Feb 2015
Location: United States
Posts: 1
Received 0 Votes on 0 Posts
I've been trying to wrap my head around this same issue for some time. I found multiple problems with my unit, which is a model covered by the manual posted earlier.

1) A wire wasn't screwed down very well on my furnace control board. It was W1 or W2, I don't remember. Maybe this was causing my unit to stay in defrost mode (fan running with only the faintest hint of heat).

2) The H terminal on the 4-pin connector of the board, as well as the corresponding yellow wire on the plug side were damaged from overheating. When I undid the connector, the pin from the board was actually stuck in the plug side. I pulled the pin out, set it aside and plugged the harness back in. I unplugged the yellow wire from the heating element and taped off the end, and the spade connector of the element. I think this element is only for the defrost cycle (someone please correct me if I'm wrong). If it is, and my unit was stuck in defrost, that might be why the connection overheated.

3) According to the manual, my blower speed should be set to high. I found it set to low instead. A lower CFM could cause the heating element to reach the high temp limit prematurely. I believe my limit switch works properly, it was closed when I tested it unplugged.

The furnace has been on for about 1.5 hours now with no sign of anything wrong. I'm trying to get the house up from 60 to 70 degrees, were halfway there.

David in Ohio
 
  #14  
Old 02-16-15, 07:27 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 57,773
Received 932 Votes on 869 Posts
Welcome to the forums.

Without posting the exact make and model we can't answer in detail.

Your air handler may have two heating element that are individually controlled.
Your blower should most likely be set to medium on electric heat and high when in A/C mode.
 
  #15  
Old 02-17-15, 08:32 AM
D
Member
Join Date: Dec 2012
Location: United States
Posts: 247
Received 1 Vote on 1 Post
you might read the thread, maybe some applicable ideas there :
http://www.doityourself.com/forum/he...t=#post2346989

did you verify that there is no airflow obstruction ?
have you measured the exit air temperature ?
did you disconnect both W1 and W2 from the heat pump - if either of those comes on, I think that the fan will run , for safety, whether or not there is a G ?
 
  #16  
Old 02-17-15, 08:36 PM
D
Member
Join Date: Jan 2015
Location: usa
Posts: 3
Received 0 Votes on 0 Posts
Found it!!

rmklc,
The defective part is the high limit in your aux heat coils.
If this limit goes over 210 deg. it sends an opens to the control board. Kind of like the limp mode in your car. Having received the open from the high limit it tells the fan to stay on, shuts down the heat and disables the thermostat. Blowing cold air most people would call the repairman. When you reset the power you reset the condition. I just ordered a new one on ebay for about 22.00. I checked mine out by shorting the two wires going to it, I think they were orange and purple, together works fine now. Mine is a part number
1nt23l-2814.
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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