Electric Furnace (only) Blower On Continuously. - HVAC - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 11-25-2013, 12:43 PM   #1
Member
 
Join Date: Aug 2009
Location: Southwest Ohio
Posts: 506
Rewards Points: 402
Default

Electric Furnace (only) blower on continuously.


[QUOTE=justplumducky;1271291]
Quote:
Originally Posted by justplumducky View Post
I only had a chance to see this furnace for a few seconds, on way out of the home. Going back this morning. I only noticed one sequencer (smaller mobile home) and a fan relay. There was also a contactor relay - was not sticking. T-stat controller was removed from its base.
Relay part number: 9400-13Q152 See pic below.
EDIT: I have both the relay and sequencer on my bench now - no diagram on the relay, but there are 6-ea terminals. 24vac coil. With long side of the rectangular relay positioned vertically in front of me,
#1 & #3 terminals are at bottom (#1 at bottom left).
#2 & #4 terminals are at top (#2 top-left).
#5 & #6 terminals are just below #2 & #4). #5 terminal at left side.

#1 & #3 are the coil terminals, and are good (continuity). With no power to coil, the only other terminals that have continuity are 5 & 6.
With 24vac applied to coil, the only two terminals with continuity are 2 & 4.

I just checked the sequencer with ohm-meter. With no 24v power applied to base, both sets of terminals (base & the only pair on top of that) have continuity across them, but someone just told me this "sequencer" is actually a limit/sequencer. After a second look, I realize now that the bottom of this "seq." looks to be a typical limit switch, with the quarter (25 cents)-sized sensor button on the bottom.

[/B]
Since the only other components in this furnace control box are a contactor relay (not sticking) and the XFMR, one or both of these units (Fan Relay and limit/sequencer) would have to be bad, correct? Changing them both would take care of the problem (FAN on constantly), unless there were a short circuit in the wires to fan motor, Correct? Warm air is also coming out of the registers when fan on.
Attached Thumbnails
Electric Furnace (only) blower on continuously.-fan-relay-pic-electric-furnace-20-billy.jpg  
Attached Images
 

Advertisement


Last edited by justplumducky; 11-25-2013 at 04:16 PM.
justplumducky is offline   Reply With Quote
Old 11-25-2013, 05:27 PM   #2
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,471
Rewards Points: 4,588
Default

Electric Furnace (only) blower on continuously.


Did you check to see if one of the trip heaters is shorting to ground.

Advertisement

__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is offline   Reply With Quote
Old 11-25-2013, 05:45 PM   #3
Member
 
Join Date: Aug 2009
Location: Southwest Ohio
Posts: 506
Rewards Points: 402
Default

Electric Furnace (only) blower on continuously.


I did not, but will tomorrow.

Googled for "trip heater" and found only the attached Pic, called a Bi-Metal Trip Heater. Is that what you're talking about? Or is trip heater the same as "heating element"? Whichever it is, I'm guessing it would have to be something behind the control panel, where the heating elements are...

I googled some more for trip heater ("images") and all I get is pics of heating elements. You must be talking about one individual element in the set of however many there are in a given electric furnace, yes?
Attached Images
 

Last edited by justplumducky; 11-25-2013 at 06:05 PM.
justplumducky is offline   Reply With Quote
Old 11-25-2013, 06:06 PM   #4
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,471
Rewards Points: 4,588
Default

Electric Furnace (only) blower on continuously.


It was a typo. Should have been Strip heater.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is offline   Reply With Quote
The Following User Says Thank You to beenthere For This Useful Post:
justplumducky (11-25-2013)
Old 11-25-2013, 11:21 PM   #5
Member
 
Join Date: Aug 2009
Location: Southwest Ohio
Posts: 506
Rewards Points: 402
Default

Electric Furnace (only) blower on continuously.


I did some more googling and determined that my relay is, indeed, working properly, as detailed in my post #1. I ordered a new sequencer/limit switch - pick it up tomorrow, will go install it, and check for grounded heat strip and/or short circuit elsewhere in Blower circuit. Report back tomorrow.

In the mean time, can anyone tell me how this limit/sequencer is supposed to work? Continuity/NC across the bottom set of terminals (for the limit function), and NO (open circuit) across the top set of terminals, for the sequencer function? Cause if that were the case, my limit/seq. is bad then - has continuity across both sets of terminals, with power off.

Last edited by justplumducky; 11-25-2013 at 11:32 PM.
justplumducky is offline   Reply With Quote
Old 11-26-2013, 05:51 AM   #6
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,471
Rewards Points: 4,588
Default

Electric Furnace (only) blower on continuously.


They may just be a dual element limit. Both closed until trip temp reached.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is offline   Reply With Quote
The Following User Says Thank You to beenthere For This Useful Post:
justplumducky (11-26-2013)
Old 11-30-2013, 02:47 PM   #7
Member
 
Join Date: Aug 2009
Location: Southwest Ohio
Posts: 506
Rewards Points: 402
Default

Electric Furnace (only) blower on continuously.


I know I shouldn't admit it, but the problem was a short circuit in the t-stat wires, due to some recent paneling work by the owner's contractor. Another lesson well-learned.

Quote:
Originally Posted by beenthere: They may just be a dual element limit. Both closed until trip temp reached.
Just thought I would add, at this late date, that you were correct. They both were limits.

Advertisement


Last edited by justplumducky; 12-11-2013 at 11:37 AM.
justplumducky is offline   Reply With Quote
Reply


Thread Tools
Display Modes

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Furnace flame and blower alternate 1harleynut HVAC 7 10-29-2013 09:53 PM
blower problems with bryant furnace. blowerissue HVAC 4 03-14-2012 12:34 AM
Quote for new furnace. Reasonable? dengle HVAC 16 03-04-2012 08:01 AM
Payne gas furnace - blower fan running continuously Ed40 HVAC 0 02-05-2011 03:19 PM
Need help with Electric Furnace and HP goodeetwoshews HVAC 7 12-17-2009 10:38 PM




Top of Page | View New Posts