Air handler fan not turning on


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Old 08-06-15, 04:22 PM
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Air handler fan not turning on

tl;dr My compressor comes on outside and lines coming in are cool, but the indoor fan doesn't always turn on (sometimes it does, sometimes intermittent, sometimes not at all).

I came across some great older threads talking about these issues, and figured I would start a new one to get some feedback and advice on electrical troubleshooting and part replacements. So I have a ~15 year old HVAC system and live in the southeast. Years ago we had some issues with the outside compressor when someone installed the wrong fan on it which caused the capacitor to fault, and then we also had a coolant leak. All of this was fixed and the outdoor unit seems to be working great and the lines coming in are cold.

The problem is that the fan in the air handler doesn't always come on. Since the air return is a floor under the air handler, I can actually feel cold air falling down and out of the return filter. When the compressor is running, sometimes the fan doesn't come on at all, sometimes it goes through many cycles of on 30 seconds, off 10 seconds, and sometimes it works fine for a long period of time (I feel like this happens when I set the temp very low, but this isn't all the time).

I have ordered a capacitor for the air handler (super cheap and easy), controlling the fan, but it wasn't bulging. Also, the fan itself doesn't feel hot. Other than this, I haven't used my voltmeter to check anything.

What sort of electrical checks should I do to try to isolate the problem? I think it is probably electrical which I should be able to fix, and given the price of parts, seems more reasonable to DIY than pay a repair man.

Bonus Material:
Here are specifics about the air handler (is a Payne unit). Imgur

Also, probably not related, but there is water all along the bottom of the unit, and it seems surprising that the wires are almost in the water (instead of being behind the access panel which is raised). Imgur
I don't think this is a real panel, but wanted to post it in case someone said it looked really weird/bad.
 
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Old 08-06-15, 04:58 PM
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The Acoil is probably frosted and dripping into the cabinet.
 
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Old 08-06-15, 05:28 PM
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It appears that your air handler uses a fan relay. When the thermostat calls for the fan to turn on, 24VAC is applied to the G thermostat terminal on the air handler. This in turn activates the fan relay which sends power to the fan (blower). The manual also mentions an optional Time Delay Relay (TDR) which can be removed from the circuit by cutting jumper wire JW1 on the air handler control board. I don't know if the TDR is operational on your board or not, however that could also be a source of an intermittent problem.

I found the manual at: http://c.searspartsdirect.com/mmh/li...L/L0610586.pdf
 
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Old 08-06-15, 07:27 PM
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Now fan isn't coming on... think it might be a warm night (low of 76)

UPDATE: The fan is not coming on at all. I let it run for about an hour, and the compressor was running fine, but the fan never kicked on (could feel the cold air coming out of the return. Next, I ran the fan only mode (which two days ago worked fine at turning on the fan), and the fan never turns on.

Any recommended electrical troubleshooting? I got my multimeter at the ready.

@Bob14525
That is definitely the manual for my unit, thanks. Since the fan isn't working at all anymore, I don't think I am going to sever the TDR, unless you still think that could be it?

(I guess because I just ordered a part and started this thread, it had to go and all out break.)
 
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Old 08-06-15, 09:15 PM
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If it is the cap the motor will be hot to the touch. If it is the board the motor will not be hot to the touch.

If it is the board (it probably is the board) you can bypass the board by connecting the wire on N.O. to the common wire (it is on the same part of the board).
 
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Old 08-07-15, 04:51 AM
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So when I run it in fan only mode, the motor does not get hot.

With the unit in fan only:
- black and yellow wires had 240 at the transformer
- the black wire then goes to the circuit board (figure 7), onto the fan relay (figure 16), and a blue wire goes from the relay to the fan motor (common yellow goes straight from transformer to fan motor). When I unplugged the blue wire from the fan relay, there was not 240 between the yellow on the transformer and the speed tap terminal that the blue was plugged into, but there was 240 between the yellow on the terminal and the black leading from the transformer to the relay.
- the motor did not run when I connected the blue wire from the motor to the black wire from the transformer (so bypassing the board and relay) using the multimeter leads though the meter read 240. (I assume this should have turned on the motor; should I leave them connected and see if the motor at least gets warm?)

(figures are in manual, http://c.searspartsdirect.com/mmh/li...L/L0610586.pdf)

Thanks for the troubleshooting help. I would like to at least come up with what parts to buy today before the weekend.

By the way, @Houston204, what is the cap you mention?
 

Last edited by Benjamin Neely; 08-07-15 at 05:15 AM.
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Old 08-07-15, 05:20 AM
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The capacitor is strapped to the blower housing. I call it a cap.

The transformer does not supply 240 volts. It is fed 240 volts. It sounds like you need a control board if the motor isn't hot.

Do you have a meter that can measure capacitance and voltage?
 
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Old 08-07-15, 05:46 AM
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I usually plug a Y connector into the relay Common terminal highlighted yellow and connect the incoming power and the N.O. (highlighted blue) wire to it to get homeowners air until I can replace the board.









Checking the cap isn't difficult if your meter has the capability. The meter that I keep on my belt while at work measures up to 2000 microfarad and runs under $40. It also measure volts AC and DC as well as Amps AC and DC.
 
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Old 08-07-15, 05:51 AM
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Wow, you just made my morning. Sorry about not being well versed on the terminology (should have caught cap), but that all makes sense.

My multimeter does AC and DC voltage and resistance, so I will check out the capacitor later today (though a replacement is arriving in the mail tomorrow as well).

Also, I will do what you said with the y-connector. Really, that is a huge help with the diagram. I need to take the kids to school, but will update later with success.
 
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Old 08-07-15, 05:56 AM
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I agree with Houston that the control board is the most likely suspect. However, the TDR may be bad. If it is, it would prevent the fan relay from energizing. My A/C outside unit has a TDR in it, and it failed after a few years, preventing the unit from turning on. Since I had a digital thermostat (time delay functionality is built into the thermostat), I jumpered around the A/C TDR, and everything has been working fine ever since.

I'm not saying that your TDR is bad, just that there's a chance it is. I would try cutting jumper JW1 to see if it makes a difference. If it doesn't, then splice it back together.
 
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Old 08-07-15, 07:55 AM
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Fan is on!!!

I connected the wires like Houston204 suggested, effectively bypassing the board, and the fan definitely works. So I guess the fan will simply run and the compressor will cycle on and off as needed?

Now I will work on getting a replacement board. I am planning on calling up Payne/Sears and going from there, but if anyone has a better idea, please let me know. I am in Charleston, SC.


Regardless, thank you thank you so much for the help. It is relatively cool right now, but it is still pretty hot to not have an AC.

UPDATE: I guess they won't sell me the board. I have a friend whose dad owns an HVAC business so will try that unless someone has another idea. Again, thanks for the help.

UPDATE2: I think this board looks right and if I can't get it elsewhere will probably order this (or unless someone tells me no).
http://www.americanhvacparts.com/p-9...t-carrier.aspx
 

Last edited by Benjamin Neely; 08-07-15 at 08:16 AM. Reason: Adding updates.
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Old 08-07-15, 09:52 AM
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Yes the outdoor unit should still cycle with the thermostat.
The conditioned space will see higher than normal humidity until the board is replaced.

You must be far away from the Houston area if it is still pretty cool outside. It is hot over here.

I would try to get the part number of that board and check their price versus Amazon's.


It is $51.12 at Amazon for an HK61EA006.
 

Last edited by Houston204; 08-07-15 at 10:50 AM.
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Old 08-07-15, 11:23 AM
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Board

Does it matter that I think that HK61EA006 is the board shown in figure 8 in the manual, and my model is the B048, which is the board shown in figure 7? From the looks of it, I can use either.

So Houston204, let me know if you think this amazon board is the one to order, or if I should do this one which is more expensive but does list my model. I am sorry to ask so much, but you seem to know what to look for.

I am going to go ahead and order the Amazon one so it will be here next week, and I can can cancel easily too.

Oh, and it is hot here, just not as hot as last week. I am Charleston and our highs are low 90s this week with storms rolling up the coast keeping us cool.

Thanks again for all of your help, my house is now cool and the dogs and fan are way happier.
 
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Old 08-07-15, 03:00 PM
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What is the HK number on your existing board? It looks like all of those models use the same board.
 
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Old 08-07-15, 04:09 PM
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I just assumed since it wasn't on the figure it wasn't on the board, but my board definitely says HK61EA006. So the part I ordered from Amazon (previous message) should work great.

Thanks again for the help. I would buy you a beer over the interwebs if I could.
 
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Old 08-07-15, 08:56 PM
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Glad that I could offer some assistance.

Amazon's board
Name:  HK61EA006.jpg
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Fig 8 board..
Name:  Payne  Fig 8  PF1MNC.jpg
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The board in Fig 8 does not show the relay that we bypassed.

I wonder what 019, 025, 031, 037, 043, and 061 translate to when we jump to Carrier models.
I suspect the Carrier FC4DN units with an ECM X13 motor.

 
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Old 08-24-15, 11:26 AM
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Sorry for a late update:

- replaced circuit board two weeks ago
- immediately everything was working great, and maybe even colder (I think it just felt that way)
- BUT, the air handler fan now cycles on/off repeatedly even when there is no call for cold.
- running fan on mode with cooling so as not to stress system and fan
- what should I troubleshoot, and is it the thermostat?

Longer reply: Almost immediately after replacing board, and house got to temp, I noticed that the fan was cycling on and off when the compressor wasn't on. At first I thought it was the "on 30 seconds, off for 10 seconds" problem which it had been doing previously (before fan relay died). But now the air handler fan cycles on/off after there is no call for cool (so the thermostat doesn't say "Cool on" and the outside compressor isn't on), and the fan will run in short spurts, or long spurts, no rhyme or reason that I can see. The outside compressor seems to be running normally (again, fan is cycling when there isn't a call for cool, and never turns off when a call for cool is on), the capacitor is old, but I don't think these symptoms align with a bad cap, and I don't know what else I could check (and everything I read doesn't make it seem like it is the thermostat).

I am sorry to ask for more help, but it would be much appreciated. Thanks.
 
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Old 08-24-15, 12:54 PM
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Does the air handler fan cycle continuously, or just for a certain period of time after the thermostat has reached the set point and the outside unit has turned off? If you turn off the power to the air handler and back on, does it still cycle? If it cycles continuously, try pulling the thermostat off it's mounting plate to rule out the thermostat. If still cycling, turn off the air handler and remove the thermostat wires where they connect to the air handler (take a picture or draw a diagram so you know where the wires go). If it still cycles, it would suggest another bad control board.
 
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Old 08-24-15, 01:10 PM
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That control board has common, normally open, and normally closed terminals.

The normally closed terminal usually connects to a heat sequencer.
This sounds like a sequencer problem.

Does the fan still cycle in this odd manner without the N.C. Wire connected? (if there was a wire there)

If this corrects the problem the electric heat strips may also be cycling so the problem should be addressed quickly to avoid a huge electric bill.
 
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Old 08-25-15, 01:31 PM
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@Houston204 and @Bob14525
Thanks for the quick reply. I got bogged down with some other house things but should be able to check things out and get back answers tonight or tomorrow night. Just wanted to let you know I appreciate the quickness.
 
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Old 09-01-15, 03:34 PM
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New board...

Sorry for the late (and long) reply. This answer is going sound rambly, but the short version is that while I was trying to troubleshoot, the air handler fan started turning on and off while there was a call for cool and the compressor was running, and this went on for a long period of time (assume relay at least was dead). To avoid the compressor running without the fan, I went ahead and connected the common terminal and N.O. like previously and have ordered a new board (which should be here tonight).

Longer story:
I had been running in fan mode, and so first switched off the fan. At first it seemed to behave perfectly, for maybe a day, and then started going on and off (without a call for cool). When I had time to troubleshoot it, @Bob14525, it was not affected by disconnecting the thermostat, and after turning it off at the breaker box, it later continued to run after the call for cool ended for about 20 minutes.

So I went up to try some of @Houston204 suggestions. To my surprise, the board was very wet. I unplugged the N.C. wire and it still ran without a call for cool. So I hooked the NC wire back in.

This is when things went from bad to worse. The compressor would come on and the blower never would. I tried turning things on and off again, and also tried running in fan mode. Selecting fan mode did nothing for the blower (so blower was unresponsive), which made me think the relay had bit the dust. I went and connected the common terminal and NO, and at this point the control board was relatively dry. The fan cranked up and has been running ever since with the compressor cycling.

So what I wonder is if my real problem is an excessive amount of moisture in this box (and why is that board not higher, btw). When I replace the board tonight, I am going to leave the bottom screws out since that seems to provide some extra drainage out of the box. Is it definitely the pan inside the unit isn't draining? I haven't cleaned the drains in a while since they seemed to be doing alright (not great).

1) Does this theory make any sense? Running the compressor without blower last month for a couple weeks killed my power bill and made my significant other quite mad.
2) Aside from adding bleach and running water up the drain pipes, anything else I should be doing?
3) Is the moisture inside definitely coming from the internal pan? My junction box outisde the airhandler had been leaking, and now I wonder if it is all related.

Thanks again for your help, and sorry for the slow response. Some crazy weather (and visiting family) has kept me occupied.
 
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Old 09-04-15, 12:44 PM
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clogged internal drain may have been the culprit all along

So the primary drain was definitely clogged and the auxillary drain too. My current setup has the primary running directly outside (with a trap of course) and the aux drain from the pan under the unit also runs outside. There is a shutoff on the pan.

My new, and hopeful theory, is that the internal drain overflowed messing up the board (and therefore the fan relay, etc), and even drained into the transfer box (which is why I also had water building up there). I thought there was an air leak and condensation was causing the leak in the transfer box, but this is a much cheaper solution. Will see how things behave over the next few weeks, but again, thank you so much @Houston204.

My next order of business will be starting some annual maintenance routine on the air handler to keep it clean and happy.
 
 

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