Intertherm furnace stays hot after fan cycle

14:53 ______________________________________________________________________ I have a mobile home with a Intertherm Air/Handler that is less than 2 years old (installed on 5/22/02). The model number is S3QA-030KA (2.5t). I also have an owners manual that lists the 2 different possible “Series” that I may own as the E2EH-xxx HB or E2EB-xxx HB Series. I do not know how to tell the difference. I have a problem and several questions. The unit heats the home to the set temp and the fan cycles off when appropriate. The problem is that I luckily noticed this morning that the heating element is remaining on (after an hour of searching for the burning smell in the home). This heats the entire unit and the surrounding area to a very hot temp. A fire seemed a definite possibility. I manually had to switch the thermostat fan to “on” rather than “auto” to cool the unit down. Repeated attemps to make the heat cycle off failed and the unit stayed hot after the fan shut down each time. I switched the unit to air conditioning to see if that cycled properly. It did but when the fan shut down the heating element is either remaining hot while the a/c is running or turning on after the a/c shuts down-I could not tell. I was forced to disconnect the power at the breaker or I’m concernerd it will burn the house down. Is there anything that can be done prior to calling a serviceman? Any suggestions of whether this may be a defective switch or something? Also, anyone know how Nordyne handles matters like this when its under 2 years or should I try to repair it myself? Replies: Xenos Webmaster “Re(1):Intertherm furnace stays hot after fan” , posted Wed 31 Mar 17:19 ______________________________________________________________________ If you are referring to am electric furnace a sequencer has failed. I have no information on this system or the warrantee status. Xenos. The best way to escape a problem is to solve it. tymbom “Re(2):Intertherm furnace stays hot after fan” , posted Wed 31 Mar 19:39 ______________________________________________________________________ Yes it is an electric furnace. Sorry I forgot to mention that. Is replacing a sequencer difficult? I’m hoping that there is only one of these. Do you know of any references to do this or would that be needed? I am also interested in whether less than 2 years of life is normal for a sequencer or if there may be an underlying cause for it? Thanks in advance Xenos Webmaster “Re(3):Intertherm furnace stays hot after fan” , posted Wed 31 Mar 20:37 ______________________________________________________________________ There will be several of them in the furnace. You will need to find out what on is sticking on and it will be a tight area with high voltage. Personally If your not well versed with power I would leave it for a professional. Xenos. The best way to escape a problem is to solve it. tymbom “Re(4):Intertherm furnace stays hot after fan” , posted Fri 2 Apr 18:57 ______________________________________________________________________ It turns out that there is only one sequencer for the Intertherm model E2EB-015 HB. I replaced it today but the heating element still stays on anytime there is power to the unit. I read an earlier post by Xenos that suggested disconnecting the “W” wire at the thermostat. I tried that but anytime there is power, the heating element stays hot-even with a shiny new sequencer… Is there any other possible reason that the this would happen? Any help would be greatly appreciated. I even found the service manual at Nordyne if that would help. rIxQV52O0BEJ:www.nordyne.com/Literature/359a.pdf+replace+furnace+seque ncer+E2Eb&hl=en&ie=UTF-8 Xenos Webmaster “Re(5):Intertherm furnace stays hot after fan” , posted Fri 2 Apr 19:52 ______________________________________________________________________ Got it. Acording to the diagram, low voltage terminal 1 or 2 ( their jumped on the diag) is powered if the heaters are on. These should be the W terminal since this is all that can power the sequencer. Xenos. The best way to escape a problem is to solve it. Xenos Webmaster “Re(5):Intertherm furnace stays hot after fan” , posted Fri 2 Apr 19:15 ______________________________________________________________________ Can you repost that link. Or email it to xenos@hvacmechanic.com Xenos. The best way to escape a problem is to solve it. tymbom “Replaced thermostat..no luck” , posted Sat 3 Apr 15:06 ______________________________________________________________________ I replaced the thermostat to rule out the possibility that it may have been bad. I checked all the connections at the furnace and everything appears ok with no loose or grounded wires. I also even tried putting power to the furnace with all the thermostat wires disconnected. The same problem though-the heating element is on anytime there is power. The blower seems to cycle normally but the heat is on, even if the thermostat is set to air conditioning There are two circuit breakers at the furnace. When the top breaker (which feeds the bottom coil only) is in the “on” position there is no heat. But, when the bottom breaker is turned on the heating element comes on immediately. Xenos Webmaster “Re(1):Replaced thermostat..no luck” , posted Sat 3 Apr 17:18 ______________________________________________________________________ Have you checked for power on the sequencers coil? Acording to the diagram it’s either powered or wired wrong if the sequencer is not shorted. Xenos. The best way to escape a problem is to solve it. tymbom “Coils are cycling…..” , posted Sun 4 Apr 10:27 ______________________________________________________________________ I powered up the heater to watch its cycle with everything tore down where it is easy to see. There are two heating element coils. When power is put to the furnace with the thermostat set to “off” and fan is set to “auto”; only the top coil energized. It would do this until the power is shut off at the breaker (or until a heat cycle comes on-see below). Here is the odd part. First, I set the heat on the thermostat at a temp it would come on when I switched it on. When I turn the thermostat to “heat” and fan to “auto”, the lower coil is energized and the top coil shuts back off. I can tell by seeing through small holes in the case. I can also tell that the heat coming through the vent is roughly “half” as warm as it was. The blower normally cyles on and off as called for by the the thermostat but half the heat. The HVAC system hasn’t been altered and worked for almost 2 yrs so I’m figuring the wiring is correct. This problem started while the heat was in use if that indicates anything. There is nothing burnt or smelling burned and I have returned all the original equipment to the furnace. Xenos Webmaster “Re(1):Coils are cycling…..” , posted Sun 4 Apr 11:53 ______________________________________________________________________ Is the sequencer powered? Xenos. The best way to escape a problem is to solve it. tymbom “Re(2):Coils are cycling…..” , posted Fri 9 Apr 18:24 ______________________________________________________________________ Did this help any? Do you need any other readings? tymbom “Sequencer power…” , posted Tue 6 Apr 12:28 ______________________________________________________________________ I’m not sure what you need so I throw out a few readings. The “heat” was “on” and the fan was set to “auto” for the tests. I checked the power at the transformer first. After disconnectng the 24v output wire from the transformer to the sequencer, the transformer reads 22v (at the transformer 24v output terminal to the sequencer). Oddly, after I reconnnect the wire to the sequencer I am only reading 11-12v at the sequencer bi-metal heater terminal. There is a limit switch (I think-its a “button” type sensor leading into the heating element box) hooked up on the other side of the sequencer’s bi-metal heater terminal. It also reads 11-12v. At the sequencers switching portions, there was 120v each (there are 2). So, the transformer puts out 22v to sequencer that shows 11-12v at the sequencer bi-metal heater terminal and it reads 120v at each switching portion. Xenos Webmaster “Re(1):Sequencer power…” , posted Fri 9 Apr 20:01 ______________________________________________________________________ OOPS…. 11-12vac for some reason you are getting a back feed through a relay or coil that is goving you this power reading. Xenos. The best way to escape a problem is to solve it. tymbom “Re(2):Sequencer power…” , posted Fri 9 Apr 22:10 ______________________________________________________________________ Can you put that in layman terms? What would a HVAC tech look for next? The only component left I can see replacing would be the transformer but it puts out 22v as called for by the service manual. What causes “back feed”? What would the next troubleshooting procedure be? Xenos Webmaster “Re(3):Sequencer power…” , posted Fri 9 Apr 23:01 ______________________________________________________________________ Some where some how either there is two resistances in series with each other that shouldnt be or there is a ground on the other side of a resistance some how. The problem may even be this resistance. I dont know how to explain this any easier. Other than, the power or common wire is not going directly to the coil and is passing through a resistance causing a voltage drop or there is a short pulling down the transformer. This is not a easy problem you have embarked on. The question you need to answer is why is there 12 vac on the coil when there shouldnt be. Xenos. The best way to escape a problem is to solve it. tymbom “Re(4):Sequencer power…” , posted Tue 13 Apr 19:22 ______________________________________________________________________ According to the service manual the transformer “should” put out 24vac to the bi-metal heater terminals of the sequencer. My transformer puts out 22vac and this is considered normal I think (service manual states it can vary from 22vac-26vac). There are 2 bi-metal heater terminals on the sequencer. One of these receives 24vac from the transformer. The other is tied into what appears to be a button style limit (?) switch. Both of these bi-metal heater terminals on the sequencer read 11-12vac. Its my understanding that when the 24vac is applied to the sequencer then it heats up a bi-metal heater terminal to allow the circuit on each heating coil to be closed. I have two heating coils and so the sequencer has 2 “switching portions” that close the circuit on each heating coil. I have 120vac on each of these terminals of the sequencer not 12vac. I hope I cleared that up. Do you need any further info to determine the next troubleshooting step? I can only think of two other visible components that could fail and they are the transformer (which puts out 22vac as called for) and some type of button style switch with two wires that is connected to one side of the bi-metal heater terminals. This switch is positioned in the cabinet containing the heating coils. Thanks Xenos Webmaster “Re(5):Sequencer power…” , posted Wed 14 Apr 17:31 ______________________________________________________________________ If you are reading 12vav across the coils something is incorrect and I cannot see it on the units wiring diagram. Follow the wiring diagram and see where the difference is. Xenos. The best way to escape a problem is to solve it. tymbom “Coils read 120vac at the sequencer…” , posted Wed 14 Apr 18:28 ______________________________________________________________________ I am not reading 12vac across the coils. I am reading 120vac across the coils. I am reading 11-12vac across the sequencers bimetal heater terminals that heat up and close the circuit on the 120vac coils. I don’t know any other way to explain it. The transformer puts out 22vac to the sequencers bimetal heating terminal (this terminal heats up to close the circuit on the coils, one at a time-there are 2). These terminals are labeled M1-M2 and M3-M4 on the wiring diagram. Each coils reads 120vac. They also read 120vac at the sequencer. Xenos do you still have access to Nordyne’s technical support website? Maybe there is more info there? I have read everything available and it doesn’t add up-even the wiring diagram. I can’t find any other info on the web either. I hope I am making any sense? Xenos Webmaster “Re(1):Coils read 120vac at the sequencer…” , posted Wed 14 Apr 20:39 ______________________________________________________________________ Look at fig 15 , what voltage do you have on terminals 1 and 3 of the top drawing? http://www.nordyne.com/Literature/359a.pdf Xenos. The best way to escape a problem is to solve it. tymbom “Re(2):Coils read 120vac at the sequencer…” , posted Thu 15 Apr 11:23 ______________________________________________________________________ When I try to acces the site you referenced I got this “You are not authorized to view this page.You might not have permission to view this directory or page using the credentials you supplied.”. Is there any way to post the PDF or send it to my email? If you can, I will let you know the voltage. If not maybe you could let me know where to test and I can give you those numbers. I am sure I could figure out where to test with some help. Also, you stated the problem is possibly the 12 vac keeping the bimetal contact hot and keeping the heaters on. Is it possible that the transformer is defective? It shows 22vac when disconnected from the sequencer but reconnected it drops to 11-12vac at the heater terminals. Thanks again for you help. Its greatly appreciated. Xenos Webmaster “Re(3):Coils read 120vac at the sequencer…” , posted Thu 15 Apr 17:17 ______________________________________________________________________ Actually that link is actually one you gave me back in the prevoius messages. You actually sent it to me. I am not sure how to download the pdf. when i click on it adobe just fires up. Xenos. The best way to escape a problem is to solve it. Xenos Webmaster “Re(1):Coils read 120vac at the sequencer…” , posted Wed 14 Apr 19:39 ______________________________________________________________________ When I refer to the term coil, I mean the relays heater coil. Not the furnaces heating coil. When we supply 24 vac on this coil the heater will heat up and switch the contacts in the sequencer and thus turn on the heaters. The way I see it the problem is this 12 vac I think its keeping the bimetal contact hot and keeping the heaters on. Xenos. The best way to escape a problem is to solve it. tymbom “Problem solved…thanks” , posted Sat 17 Apr 21:44 ______________________________________________________________________ I called Nordyne customer service 1-800-4AC-HEAT (I figured I’d post it as its hard to find the toll free#). Although Tech support could not give me a password to the literature on their website because its for Techs only they were really helpful and faxed me a copy of that wiring diagram (before I got it to download). That link to Nordyne eventually did work and I got the .pdf to load after an update. Figure 15 was for a different model. The E2EB-015 HB was on figure 21. After checking out the new .pdf service manual I decided to check the coils for continuity at each end(power off and wires disconnected). The bottom coil showed continuity but the top did not. I removed the coil assembly to find that the top one had broken, melted downward and welded itself to the bottom coil. I replaced the coil assembly which consisted two coils parallel to each other (Nordyne part #903906). It fired up no problem now. The heat and air are working perfectly. Thanks for the help! talbert97 “Re(1):Problem solved…thanks” , posted Fri 5 Oct 22:08 ______________________________________________________________________ quote: ______________________________________________________________________ I called Nordyne customer service 1-800-4AC-HEAT (I figured I’d post it as its hard to find the toll free#). Although Tech support could not give me a password to the literature on their website becau … ______________________________________________________________________ You wouldn’t happen to still have the wiring / installation diagrams would you? C.T.

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