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BillyHvac
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22680
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Blower motor energizes intermittently. I have 5 flashes

Customer Question

Blower motor energizes intermittently. I have 5 flashes (call for heat error code). Also, Induced draft motor occasionally comes on like heat has been called for... I have changed control board and rewired thermostat as well... still no joy... James
JA: Sometimes, James, HVAC issues that that you think will be really complicated end up being easy to fix. The HVAC Technician I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the HVAC Technician should be aware of?
Customer: not so far
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Submitted: 1 year ago.
Category: HVAC
Expert:  BillyHvac replied 1 year ago.

Hello,

My name is Billy.

What is the make/model of the unit?

Customer: replied 1 year ago.
Evcon / Coleman DGAT056BDF
Expert:  BillyHvac replied 1 year ago.

does you system have a blendaire ventilation package built in with it?

Customer: replied 1 year ago.
no
Expert:  BillyHvac replied 1 year ago.

thank you...so the inducer motor kicks on without a call for heat? and the main blower kicks on for no reason?

Customer: replied 1 year ago.
that correct. Intermittently, Gotta love it :-(
Customer: replied 1 year ago.
usually after a cool or heat cycle has finished
Customer: replied 1 year ago.
P.S replaced thermostat wiring and batteries, even changed out the control board as well... still no joy
Expert:  BillyHvac replied 1 year ago.

If you changed the control board..this can only be caused by a bad wire somewhere.

The inducer can only be turned on by a signal from the board. The board can only do this if there is a call or a bad limit wire somewhere.

When limit opens or a wire in the limit circuit, it brings on blowers as a safety feature. You will need to search all wiring starting at thermostat to furnace...and then the wiring in the safety circuit.

Usually this would be indicative of a bad board...but since yours is new.it leaves wiring issues.

Customer: replied 1 year ago.
hmmm, Ive checked much of the wiring already. I found the Thermostat wiring was nicked (hence the changing out) I have also checked the blower motor wiring as well. My thinking was that the blower was getting energized (rubbed through the wire shielding somewhere) but found nothing so far. I stopped looking because I noticed the intermittent 5 flashes on the control board (heat call error)
Expert:  BillyHvac replied 1 year ago.

the damage we are looking for (or switch) is the safety temp sensors on the front wall of furnace.

Whether it is a wire or switch...after board that is the only thing that can bring on the 2 fans

Customer: replied 1 year ago.
The limit wiring makes sense though...thinking... if the limit opens...too much heat (overlimit) fan comes on right?
Customer: replied 1 year ago.
ok, I'll check into it... will I connect back to you when finish troubleshooting?
Customer: replied 1 year ago.
email ... leave chat window open?
Expert:  BillyHvac replied 1 year ago.

just respond when you can....I have also seen these units start the blower in summer because of too much heat in the furnace from the vent pipe in the hot summer sun...

Just sign back in when you are ready

Expert:  BillyHvac replied 1 year ago.

just respond to one of the emails

Customer: replied 1 year ago.
ok right It will likely be a few hours till i get back but I will have all items checked out when I respond again late this afternoon
Customer: replied 1 year ago.
P.S. Ambient temp is only 76 degrees right now
Customer: replied 1 year ago.
one other crazy message i saw twice was 2 flashes (combustion air switch stuck)... Gremlins
Expert:  BillyHvac replied 1 year ago.

sounds like board..but I guess a rogue wire could do this

Customer: replied 1 year ago.
I'll be back in a few hours... thanks.. James
Expert:  BillyHvac replied 1 year ago.

ok, just keep this on your end until ready or the system forces a response from me.

Billy

Expert:  HVAC Guru replied 1 year ago.

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Answer

I am a different tech, I would disconnect the thermostat wiring to the control, see if it ever turns on by itself without the thermostat wiring connected. This would rule out the thermostat wiring or possible low voltage feeding the board issue with a false signal through ground from the thermostat wiring basically a backfeed of the circuit can cause this. I would do that as that would be the fastest way to rule out a board issue and to narrow down the issue. Often this is caused do to a thermostat grounding issue or bad ground at the board. Check it out and see.

The only way I receive any credit at all for my time is by you selecting a STAR USING THE 5 STAR or VOTING RATING SYSTEM AT THE TOP OF YOUR PAGE before you leave for me so please make sure you are rating me not another tech. If you are not happy with the service please let me know before leaving a negative rating. This will also allow you to get directly back to me for FREE follow up questions and tips are greatly appreciated! Thanks GURU

Expert:  BillyHvac replied 1 year ago.

We already know the board is new..You already replaced thermostat wire.

The tech that popped in did not read what all you have done. The previous recommendation is not a logical way to proceed. To check things you have replaced already is silly.

If you want to keep on track as we were just disregard and stick with me. Just let the apprentice trying to get involved know we already have those things under control and you are continuing with me.

Billy

Customer: replied 1 year ago.
Thanks for the update Billy Sound like the other guy didn't have all the info. btw I'm still checking the wiring I just got back about an hour ago... What i've found out is something i did not realize earlier.. I believe my problem is not a low voltage problem after all... both items that come on intermittently are both 110 vac right? The induced draft motor and the blower are both line voltage.... ok, back to checking the wiring now... James
Expert:  BillyHvac replied 1 year ago.

it is low voltage that triggers the high voltage. Pull a wire from a 24v limit and the fan kicks in...a loose wire in the safety circuit can trigger the fans,

When a limit opens the furnace "thinks" there is heat present and triggers fans by default.

Customer: replied 1 year ago.
Yeh, that's right... I won't abandon my search on the lower limit. Thanks... James
Expert:  BillyHvac replied 1 year ago.

good luck and keep me posted.

Billy

Customer: replied 1 year ago.
Hey Billy, ... I'm still here, just wanted to let you know i checked out what you said... and the blower does energize on when disconnecting the limit switch (like it should) started again today on my troubleshooting the wiring... just wanted to update you
James...
Expert:  BillyHvac replied 1 year ago.

thank you

Customer: replied 1 year ago.
Hey Billy, I have not found any chaffed / cut wiring... I have to turn off my unit at night because the blower 'clicks' on and off every few minutes...what else can I look for?
James
Customer: replied 1 year ago.
Hey Billy, I think I will start replacing each sensor wire One at a time... I will replace it with the same gauge and color... maybe I have a wire that is breaking internally or at the connector?
Expert:  BillyHvac replied 1 year ago.

on the control board...tell me what color wires are on what terminal that come from the blower motor

Customer: replied 1 year ago.
On the control board on the heat terminal are two wires red and brown ... the cool terminal wire is black... also has the common 'white' wire connected to the common terminalJames
Expert:  BillyHvac replied 1 year ago.
There should not be 2 wires on heat terminal unless you are feeding an accessory...what does brown wire go to
Customer: replied 1 year ago.
Billy, The Brown wire connects to the blower motor molex connector (jumped on the blower side of the 6 pin connector to the red 'cool' wire connection).James
Expert:  BillyHvac replied 1 year ago.

Is there a chance you could post a pic of that?

Customer: replied 1 year ago.
OK, here is a couple of pics of the wiring
James
Expert:  BillyHvac replied 1 year ago.

thank you!...now we are on track...is the schematic on the furnace door panel clear enough for a picture?

Customer: replied 1 year ago.
sure i'll send it to you
James
Customer: replied 1 year ago.
Billy, here are a few of the cover...
Expert:  BillyHvac replied 1 year ago.

and you are positive you do not have a blendair system where an exhaust on roof runs to keep home from creating mold?

Customer: replied 1 year ago.
I only have natural draft vents on the roof... none of them are powered vents.
James...
Expert:  BillyHvac replied 1 year ago.

as a test...remove the brown wire or pull off HEAT and tape...

then tell me if the issue stops

Customer: replied 1 year ago.
Sure no problem, I'll leave the heat 'brown' wire disconnected from the control board & see if it the blower comes on without any call for heat or
cool...
It may take a while before it happens... But I'll let you know if it comes on w/o a call...
James
Customer: replied 1 year ago.
Blower came on a few seconds after applying power and blinked five times 'gas valve error'...
James
Expert:  BillyHvac replied 1 year ago.

now put brown back.

Remove red wire from thermostat terminal strip on board terminal R.

Try same....NOTE, do not expect heat or cool during this but we need to know if blower starts

Customer: replied 1 year ago.
OK, Billy, I have reconnected brown wire and pulled the 24 volt red wire going to the thermostat... Right? Ambient temp is about 55 degrees... It been powered up for 15 minutes or so and no blower or errors thus far...
James
Expert:  BillyHvac replied 1 year ago.

so how has it been thus far?

Customer: replied 1 year ago.
Hey Billy, Still no Joy... I came home and noticed the blower motor running, relays 'actuating', and showing two different flash codes... First one as before 5 flashes (gas valve call error) and a new one 4 flashes (limit switch open). So I ohmed out both limits and they show good continuity...still sounds like wiring right?
James
Expert:  BillyHvac replied 1 year ago.

was this with R hooked up or not?

Customer: replied 1 year ago.
no the red wire to the thermostat is still disconnected...
James
Customer: replied 1 year ago.
did you mean the 24v power in to the board?
Expert:  BillyHvac replied 1 year ago.

give me a a pic of the entire board.

we may have a harness issue....with R unhooked it totally eliminated thermostat and all thermostat wiring...and no 24v input to board...

Customer: replied 1 year ago.
there is no power to the thermostat... therefore the inability to pass 24 v back to the board.
I'll send the pics to you next message..
James
Customer: replied 1 year ago.
OK here are few pics...
James
Expert:  BillyHvac replied 1 year ago.

no pics yet

Customer: replied 1 year ago.
you cannot see them?
Customer: replied 1 year ago.
I can send them again...
Customer: replied 1 year ago.
OK I am sending them with this message...
James
Expert:  BillyHvac replied 1 year ago.

the large plug on the board...remove an inspect the metal connectors in the plug...push all wire in...look for any white powder, rust or burnt points...

Customer: replied 1 year ago.
ok, checking 'P1' (9 pin molex) plug now
James
Customer: replied 1 year ago.
all 8 eight pins look good NO burns, corrosion etc... I pushed and pulled on all 8 wires they were all firmly connected in the molex plug..
James
Customer: replied 1 year ago.
I'm going to begin replacing my female spade connectors on my limits and use an emory board on the male tabs .. I do not have the right size pins for the molex plugs, but, I will get some later... Maybe this will reveal the intermittent problem?
James
Expert:  BillyHvac replied 1 year ago.

I can tell you that the issue is in the furnace and not external....

Customer: replied 1 year ago.
Hey Billy, Just an update. I have bought a window unit to remove some of the heat at night since my central is still acting up intermittently... As far as the central wiring I have changed out several female spade ends (no joy) now I am replacing each wire. one at a time...
James
Expert:  BillyHvac replied 1 year ago.

you may want to bypass each limit also to see if one is opening and tripping blower.

Customer: replied 1 year ago.
hey Billy, my symptoms have changed a bit...I replaced the wiring on the limits and i have the lower limit jumped out... The cool cycle just finished and the condenser shut off, however, now the blower will not shut off... I get 3 flashes over and over (combustion air switch failed to close) That switch is only used in the heat cycle right? for combustion air. Right?
James
Customer: replied 1 year ago.
Update... the blower dropped out for a moment then came back on because of a call for cooling...
Expert:  BillyHvac replied 1 year ago.

remove the W wire that mounts on circuit board from thermostat.

does it still cycle on 3?

Customer: replied 1 year ago.
I removed the heat wire (w) and turned power back on... immediately blower cycled on and off three times in less than 1 minute then showed 2 flashes air switch stuck closed... blower then shut off while board continued 2 flashes over and over.. I then powered off unit myself...
James
Expert:  BillyHvac replied 1 year ago.

ok it is getting narrowed down....your air switch..is it a pressure switch with a rubber tube or is it w ires going into the side of the exhaust motor?

Customer: replied 1 year ago.
it has tubing to detect airflow from the draft motor down to the combustion chamber.
Expert:  BillyHvac replied 1 year ago.

unhook those 2 wires that come from the air switch and tape off separately then try again

Customer: replied 1 year ago.
hmm. ok I will, but that will show up as open circuit right?
Expert:  BillyHvac replied 1 year ago.

only if it were heating...the circuit is open when the exhaust fan is off.

The circuit should not be reading closed when exhaust fan is not running. Unhoooking this will have no effect in cooling

Customer: replied 1 year ago.
yeh I didn't know that but it makes sense. ok so far, blower has not come on and steady green light. no errors
Customer: replied 1 year ago.
should i try a cooling cycle now?
Expert:  BillyHvac replied 1 year ago.

yes please

Customer: replied 1 year ago.
ok cool cycle has begun...
Expert:  BillyHvac replied 1 year ago.

I am wondering if the pressure switch micro contacts are making connection and bringing on the blower....this is in the safety circuit and could be the entire issue.

A bad pressure switch

Customer: replied 1 year ago.
ok it cycled off from cool and blower did not come back on so far and no errors... ok a bad combustion air switch? It can cause gas valve, limit switch, and causing the blower to come on all despite it not being on heat mode?... wow. Also I still have 1. the heat leg removed from the thermostat. 2. the lower limit jumped out. and 3. the air switch disconnected... 15 minutes and no random energized blower is a record for this unit...
Expert:  BillyHvac replied 1 year ago.

put everything back in place except pressure switch wires...and lets try again,

That includes putting heat leg on and unjumping limits

Customer: replied 1 year ago.
ok, will do reconnect all except combustion air switch.. sry. its doing it again... 2 flashes even though its disconnected?
Expert:  BillyHvac replied 1 year ago.

what is 2 flash code?

Customer: replied 1 year ago.
the combustion air switch stuck closed
Expert:  BillyHvac replied 1 year ago.

could you please post a pic of the exhaust fan motor and pressure switch?

Customer: replied 1 year ago.
sure
Customer: replied 1 year ago.
Expert:  BillyHvac replied 1 year ago.

Ok I see the pressure switch..but not exhaust..

In thermostat there is not a wire on B terminal is there?

Customer: replied 1 year ago.
B" no, this is single stage gas heat...no connection here ...ok - exhaust pic...do you want the combustion blower motor?
Expert:  BillyHvac replied 1 year ago.

yes please

Customer: replied 1 year ago.
np be right back
Customer: replied 1 year ago.
Expert:  BillyHvac replied 1 year ago.

alright...last shot..

It codes that the pressure switch circuit is closed.

And this is with the pressure switch unhooked.

Folloow the 2 wires from the pressure switch to the board.....if there is no connection between those wires before they get to board...short, another control..then you have a bad board...even if it is new.

If it thinks the pressure switch circuit is closed when it is not even hooked up..then the board has a defect.

Customer: replied 1 year ago.
I bought it at Johnstone supply hopefully the will exchange it.... the weird thing is that the other board has the same faults too.
James
Customer: replied 1 year ago.
Ok Billy, I returned the control board to Johnstone Supply for a warranty return. I have now put in the 'new' board and reconnected everything, removed jumpers all of it...The good part is i'm not getting limit switch errors or air switch errors now... yeh... However the intial problem is back the 5 flashes 'Gas valve energized with no call for heat'This tells me two things.... First of all, My original board was a good board as well as the board i put in today. and Secondly, this error '5 flashes' is being caused by something else than the control board (duh)..Ok, that was a long update Billy, But what can i check now that we're back to the original problem...
James
Customer: replied 1 year ago.
Argh... I spoke too soon ... after the cool cycle finished , the unit shut off as it normally should but i heard a relay energizing and before i could get back there to it the induced draft motor came on and then a few seconds later the blower comes on (like a call for heat) the then 3 flashes again 'combustion air switch failed to close' over and over 3 flashes
I just shut if off...
Expert:  BillyHvac replied 1 year ago.

lets unhook the gas valve wires...there is something shorting somewhere..but it takes a call on w terminal to get 24v to valve.

So lets drop the gas valve out...and lets see what happens

Customer: replied 1 year ago.
ok will do. I'll disconnect gas valve wiring. Turn unit back on and wait...
James
Customer: replied 1 year ago.
well after running a cool cycle i got the 3 flashes code again 'combustion air switch failed to close'
Customer: replied 1 year ago.
Ok Billy, I have disconnected the air switch again, and turning on unit...
Customer: replied 1 year ago.
Ok still getting, 2 flashes 'combustion air switch stuck closed' in cool mode. (air switch is disconnected). I also have lower limit jumped out again (may be going bad-sound strange?)A brand NEW finding (for me) is that 'occasionally' the blower drops out during a cool cycle (yes, condenser is running) Then blower immediately comes back on to finish call for cooling. This blower dropping out may be related to this safety circuit problem?James
Customer: replied 1 year ago.
update... Hey Billy I have a thought...
I've looked at all the components that i have jumped out or removed from the circuit and come up with this idea... every thing is thermally (heat) related... also its a cool day again.... therefore, not many calls today for a cool cycle.. but there have been at least 5 successful cool cycles today with no errors spread out about 1 call per hour or so... Am I missing something?
James
Expert:  BillyHvac replied 1 year ago.

you bypassed pretty much everything that can start the blower as far as safety switches....is there a snap disc switch that maybe we didnt get?

Customer: replied 1 year ago.
Snap disc switch? Do you mean a thermal overload?...
Customer: replied 1 year ago.
the only snap switches i have seen are the two limit switches the upper is a manual reset and the lower is automatic style. The parts list doesn't show any more either....Ok I have another idea, I've been looking in my old 'GTH' school books and the theory seems to suggest that if the HSI was energized (wiring grounding out) that could cause the lower limit to open (from the heat) and possibly 'believe' that gas valve error..? What do you think? maybe disconnect the HSI for test purposes...?
Just a thought...James
Expert:  BillyHvac replied 1 year ago.

you can unhook but you would have likely noticed the unit on . hot, limit open etc..

This one is surely a tough one

Customer: replied 1 year ago.
Hey Billy, just an update... I have had very few coded errors last few days (I still turn off at night though). I have so much of the the heat and limit circuits disconnected I think i will start to reconnect them one at a time. I will start with the heat leg (W) and wait several cycles before i move to the next wire. I ordered a lower limit (be in tomorrow)...
James
Expert:  BillyHvac replied 1 year ago.

just keep me posted..

Billy