E2EB-012HA Heater w/AC - SOLVED

Questions about repairs and parts for Nordyne furnaces, air conditioners and heat pumps for manufactured homes including Intertherm, Mac and Miller brands. Click here for Nordyne parts.

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mscott

Tue Dec 04, 2007 1:19 am

Blower fan comes on if I turn it on manually, or have it in A/C mode, but not in heat mode. Tested for 240 volts AC on sequencer at M1-M2, M3-M4, M5-M6, got nothing. Assumed this meant bad sequencer, as did get 24 vAC on H1-H2, H3-H4.

Replaced sequencer, same situation is occurring. Have been watching voltages with t-stat set to heat, and 85 degrees. Noticed that it appeared the power to the sequencer appears to come through the heating coils first, and then into the sequencer. Getting voltage to the limit switch on one side, and when it clicks on, I do get voltage on the other sides, appearing to go into the box behind it, and into the heater coils. They don't stay on very long (about 10 second), I see them glowing red-hot from some holes into the box, and it clicks off, at which point the voltage drops. (Should they glow red-hot, or is this abnormal?) On the other side of the coils, which connects to the sequencer, and from what I can tell should also read 240v, I usually get in the millivolt range (nothing). I think I have seen it get to around 120 volts, but its hard to tell if my voltmeter was just saying 120millivolts, instead of volts at the time.

I checked for a short to ground on all four terminals of the heating coils, discovered none, and got about 9.2 ohms of resistance between each side, on each coil.

I pulled the wires off the limit switch one pair at a time, and got continuity between them while it was cold. This makes sense, as I saw 240 volts on one side after it had clicked on, it just only lasted a couple of seconds before it went off.

I tested the relay (even though I assumed it was okay since I got 24v at the sequencer), and I got 240v and 24v on their respective sides.

At this point, I figure its either got to be the heating coils, or the limit switch.

Mark Scott
Last edited by mscott on Tue Dec 04, 2007 10:18 pm, edited 1 time in total.


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hvac1000
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Location: Cincinnati ohio

Tue Dec 04, 2007 2:28 am

The coils will glow if the blower is not working. It is not suggested that you run your furnace under those circumstances. Follow the wiring diagram on your unit to track the problem down. If you feel the sequencer is defective holding off your blower I would just jump the blower terminals on the sequencer to see if it works.
God, grant me the serenity
to accept the things I cannot change;
the courage to change the things I can;
and the wisdom to know the difference.

mscott

Tue Dec 04, 2007 10:18 pm

Thanks for posting, the problem is now fixed. When I ordered the sequencer, I also ordered a capacitor as preventative maintenance. Well, I hadn't installed that yet, as I assumed that the old capacitor was fine, I mean, that fan came on. I didn't realize until installing the new cap, how quickly that fan was supposed to come on. It really comes on quickly with force now, and in heat, it comes on as well.

I suppose it just didn't have enough umph to spin up the motor from the sequencer, and bypassing it allowed it to start at all.

I would have tested the capacitor sooner, but my multimeter with capacitor tester is kaput, and I haven't gotten it replaced yet. I didn't want to add more to the equation. Sure glad I ordered the cap at the same time, as I wouldn't have specifically assumed it to be the problem, just knew that it was relatively common to need to replace them.

Thanks!

Mark

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Robert
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Fri Dec 07, 2007 3:41 am

When you get 24-28vac at H1/H2 and H3/H4 and so on, IF the sequencer is good, you should get 0vac across M1/M2, M3/M4, etc....





Thanks,
Robert
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?

mscott

Fri Dec 07, 2007 2:44 pm

This holds true, as long as the temperature limit switch hasn't cut the elements off, which in turn kills voltage to the sequencer, on my model, with only one sequencer.


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Robert
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Mon Dec 10, 2007 3:50 am

IF that happens and you get unusual readings, you then OHM the sequencer to eliminate and jumper each limit in turn to locate problem.

You also test each leg to ground , which would send you to the limit if it was open.

You had stated you were surprised to get nothing at the M terminals since you got 24vac at the H terminals.

I was just saying that if you had the 24vac, if sequencer was working, you would get 0vac across those M terminals.


The voltage comes to sequencer from both sides to equal 240vac when the sequencer is energized and the contacts close.



Thanks,
Robert
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?

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