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Old 12-28-2012, 09:52 PM   #16
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Sears Heater system doesn't stop


the only thing I have to help me wire it is a worn schematic on the back of an access panel. I'm going to take a picture of it and post it here because it's like an archaeological hieroglyph that will be understood only by people who voted for or against Eisenhower. The owner's manual looks like it was made by the same publishers of the "What you need to know about the Atom Bomb." pamphlet. unfortunately the manual is for the long replaced A/C unit.

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Old 12-29-2012, 01:30 PM   #17
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Sears Heater system doesn't stop


For the first time the fan switch on the thermostat worked in the sense that when I turned the switch to on, the fan came on. but when I turned it to auto and turned the heat on the fan never came on. I can manually turn the fan on with the stat switch but it's still giving me a headache. I really suspect it's either scrap the whole unit and start baking brownies to fund raise or personally rig the whole thing to work because no licensed repairman would work on it. I saw sparks from the insulated mount of the squirrel cage which leads me to think the whole frame is shorting to 120v.
the sequencer is represented in this picture as clutch coil "timer". or maybe the sequencer was a later upgrade in 1980. one thing that bothers me is the transformer that I Replaced had 40va printed on it. so it wasn't original but that's the specs of the new one. does it matter? ANother problem with this schematic is the stat is not accurate. I guess in 1958 the fan control was part of the unit and not on the stat. Now there is a yellow A/C control wire and a Green fan relay.


here's a picture of the fan relay. it's the only thing I haven't replaced because I can't find a match.

Last edited by oggy bleacher; 12-29-2012 at 01:35 PM.
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Old 12-29-2012, 01:41 PM   #18
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Sears Heater system doesn't stop


I'd look to see what was sparking at the blower before just getting another fan relay.

http://www.famousparts.com/90sprel.html

The above relay works in place of the fan relay you have.
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Old 12-29-2012, 07:48 PM   #19
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Sears Heater system doesn't stop


I investigated and found that two of the elements that I had stretched and reattached had both burned out again and then the dangling part drooped down so it touched the metal cage that holds the ceramic posts. so the element was still working because it was shorting directly to the frame of the heater. Another reason why there is no fixing a broken heater element. So I took those two elements out and am left with two of four that never broke to begin with.

but I don't know enough about these limiters and relays and the schematic is only partly up to date. all the info has been baked off one of the sensors so I don't even know if I replaced it with the right part. The heat comes on but the fan won't turn on automatically. I took apart a limit switch that says "off at 200 degrees" and it's ancient also with this lever system that pushes a small pin into the switch. The pin is stuck depressed but that means it's stuck in the closed position since I don't think the unit ever got over 200 degrees.

I think when I turn the fan switch at the stat to ON that overrides the heat setting so it immediately turns the heat off.* reading the stat manual tells me that actually when the fan is switched on and the heat is selected the "heating system cycles from thermostat; fan runs continuously." So, it's a puzzle why the heating elements shut down when I turn the fan to on. I suspect a miswiring.

according to the motor label and the schematic it's a 240v motor. So I'm thinking of wiring the black motor wire to the load side of the sequencer so when the heat is on, the fan is on. no limiter sensors, but I don't know how to complete the circuit once I remove that part. The black motor line branches off all over the place, to one sensor then to the limit switch that's stuck closed, then to the transformer. And the same branch goes directly to the fan relay but the color codes are a mess as someone used a chunk of the brown relay wire to bridge the distance between the black motor wire and the red relay wire.

It's possible the relay and the limiter switches have failed in a way that prevents the motor from turning on when the heat comes on but the way it acts makes me think something is wired backward. Also, it's obvious only amateurs like me have worked on this unit in the past 40 years. The killer is that it's merely a glorified space heater and it really is a boat anchor but the realities of a fixed income of the owner and general poverty of everyone involved makes me not want to give up yet.

I'll restring the elements, replace the relay and the limiter switches but I still need help wiring it.

I can post a picture of a labeled and numbered schematic of what actually exists in the unit. If anyone is up to the challenge then maybe we can team up and wire it by the book.

Today I moved the thermostat and re-stripped all the wires. I have crimping tools and blade terminations and new 10ga wire at the hardware store. I've tested for continuity at the terminals but I can't vouch for the resistance.

The only reason I've gone this far is because Jan 7th is the earliest a serviceman can see it. And I know he's going to charge $100 to tell me it can't be fixed so I'm trying to fix it myself and cancel the appointment. And even if it can be fixed he'll be at least a week ordering the parts. I really feel I can learn basic HVAC wiring in 2 weeks with a little tutoring so it makes no sense to wait. At least we found a few space heaters for the cold nights.

In case anyone is wondering I replaced the thermostat with a white rodgers 350 that replaces everything but a hydronic zone heat stat. I don't think the old one was broken but now I'm not sure either thermostat is right for this unit because of its age. The same problem happens with both thermostats. When switched to Heat/Auto the heat comes on but the fan is off. I've got the heat anticipator set to .4 amps because that's what the old stat was set for but I can't find any stamp for the actual rating.

Last edited by oggy bleacher; 12-29-2012 at 09:54 PM.
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Old 12-30-2012, 01:58 AM   #20
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Sears Heater system doesn't stop


Problem was probably the fan relay or a sequencer, not the stat.

Won't learn HVAC wiring 101 in 2 weeks. but might be able to rewire your unit up to work with the new parts.

I'd probably just wire the blower up to run 24/7, and let the stat control the 2 remaining strips, until I had the parts and restring kits.
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Old 12-30-2012, 02:59 PM   #21
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I think something is wired wrong also because turning the fan on shouldn't affect the heating elements at all. I understand why the A/C control wires go to the fan relay but I don't understand why one A/C control wire also goes to the sequencer. What business does the A/C have with the heating elements?
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Old 12-30-2012, 03:05 PM   #22
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Depending on which wire it is. its just using the sequencer as a convenience terminal.
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Old 12-30-2012, 04:00 PM   #23
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I think it's all there now. that fan limit switch in the upper left is probably what the fan relay replaced when the thermostat got upgraded. that is a probe sensor and the pin still works on it. the limit switch at the top "Off at 200" is stuck with the pin depressed. I tried to get the pin unstuck but can't get a grip on it because it's so small. forgive the incorrect symbols but the wiring is what it is right now. if you can recommend a way to turn the fan on when the heat comes on that would be a temporary solution I could live with.

Last edited by oggy bleacher; 12-30-2012 at 04:24 PM. Reason: left out one 120 wire to limit sensor
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Old 12-30-2012, 04:13 PM   #24
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Sears Heater system doesn't stop


Connect one wire of fan to the #2 terminal of the sequencer, and to the L1 line. then when the sequencer energizes the strip the blower will run. make sure if #2 or $ closes first on the sequencer, you want to connect to the one that closes first.
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Old 12-30-2012, 04:31 PM   #25
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Sears Heater system doesn't stop


http://www.airconditioningofsanantonio.com/
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Old 12-30-2012, 05:02 PM   #26
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Sears Heater system doesn't stop


Quote:
Originally Posted by beenthere View Post
Connect one wire of fan to the #2 terminal of the sequencer, and to the L1 line. then when the sequencer energizes the strip the blower will run. make sure if #2 or #4 closes first on the sequencer, you want to connect to the one that closes first.
Yes, I picked those two to land the elements on because they were the ones that came on first. That's the idea I want to work with but if I disconnect the black that goes to the fan relay and the sensor then I'm breaking part of the transformer circuit.

I don't want to get it wrong. do you mean an additional L1 branch? Or a straight shot to the #2 terminal since that is L1 when the sequencer closes...like this?


Last edited by oggy bleacher; 12-30-2012 at 05:26 PM.
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Old 12-30-2012, 06:09 PM   #27
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Sorry. Meant one wire of blower motor to L2 and the other ie from motor to #2 of the sequencer. Only move the blower motor wires, not any other wires.
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Old 12-30-2012, 06:53 PM   #28
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Quote:
Originally Posted by beenthere View Post
Sorry. Meant one wire of blower motor to L2 and the other ie from motor to #2 of the sequencer. Only move the blower motor wires, not any other wires.
So move the line input to the motor from L1 to L2. Then run the black motor wire to the load side of the sequencer #2.
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Old 12-30-2012, 07:44 PM   #29
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yes..
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Old 12-31-2012, 01:27 PM   #30
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Sears Heater system doesn't stop


I changed the motor breaker line to L2 and then routed the other motor line to the sequencer terminal #2 and the blower comes on as expected when the sequencer kicks on but it looks like having only two elements isn't enough because the blower cools them down to the point they don't emit much heat. the elements will glow red hot until the blower comes on and then only the areas that are protected from the wind at the ceramic posts will remain glowing. as far as I can see the voltage always stays the same. I moved the blower motor to terminal #6 of the sequencer and it didn't change anything. it seems #6 and #8 kick on at the same time as #2 and #4 and the elements still cool down. It's either that or the motor is drawing most the amperage leaving little for the elements. I put the other two broken elements back in hoping they act as a wind screen but that didn't change anything. The two elements still glow only at the ceramic posts. I was going to restring the elements anyway so if this same problem happens with four glowing elements then something is still wrong. I guess there is a tiny bit of warm air coming from the vents so it's an improvement. I'll order a new relay and probe sensor too and next week start all over again.

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