coleman presidential II 7670C856 blower wont start


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Old 11-22-22, 05:30 PM
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coleman presidential II 7670C856 blower wont start

coleman presidential II 7670C856 the burner lights but the blower wont turn on.I have already replaced the capacitor!Please help!!
 
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Old 11-22-22, 05:57 PM
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Welcome to the forums.

The Coleman furnaces are very vague by model number.
Is that a gas furnace with a split A/C system ?
If yes..... does "fan on" work on the thermostat ?

Is there a wiring diagram you can post ? ........... How to insert pictures.
 
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Old 11-26-22, 07:37 AM
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First, have you checked the heat exchanger in this very old furnace? It may be cracked or rotted and if so is dangerous to use.
Is there power to the motor?
 
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Old 11-26-22, 10:42 AM
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Do you have a volt meter so you can measure for 120 volts going to the motor?
 
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Old 11-26-22, 11:25 AM
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There won't be "fan on" control there.
I split, enlarged and labeled your diagram.
You either have a defective motor or fan switch.
When the furnace comes up to heat.... the fan switch shorts and powers the blower.
You can carefully short the two wires on the fan switch.
 
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Old 11-26-22, 04:32 PM
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Measure the fan relay orange and black wire connections.
110 volts is potential voltage.
It should give you 0 volts if the relay is calling.
110 volts here means that the relay isn't closing the circuit.




 
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Old 11-26-22, 05:08 PM
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Heat exchanger will be where the burner is located. For an old furnace inspection is MANDATORY.
Cracked heat exchangers are a carbon monoxide risk.
 
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Old 11-26-22, 05:18 PM
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The relay says time delay relay on it.
 
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Old 11-26-22, 07:31 PM
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Sounds like the relay is not sending power to the blower.

Do you have power to the two green wires at the relay base?
 
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Old 12-04-22, 09:54 PM
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Houston204, I can't thank you enough! I replaced the Camstat and of coarse it worked so thank you again!! I already had a few carbon monoxide detectors in place but I added one and replaced the ones I had just in case!Do you happen to know an better way to adjust that air sliding thing that the gas valve blows gas through on its way to the burner?
 
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Old 11-26-22, 04:50 AM
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Pic



 

Last edited by PJmax; 11-26-22 at 11:22 AM. Reason: split pic and labeled
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Old 11-26-22, 04:53 AM
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Gas furnace,No AC,Fan on doesn't work
 
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Old 11-26-22, 04:58 AM
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model no.7670C856 This furnace is very old in a mobile home
 
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Old 11-26-22, 02:41 PM
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New pic.


 
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Old 11-26-22, 02:50 PM
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I don't know how to check the heat exchanger Nore where to test for power at the motor.
I do have a multimeter.
That was a pic of what I actually have going,there is also a switch on the housing of the squirrel cage.
 
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Old 11-26-22, 04:37 PM
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@ Houston.... there is no fan relay.... is that the fan switch ?

What is this ??
 
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Old 11-26-22, 07:10 PM
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more pics









Hard to explain when I can't see all at once!
 
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Old 11-26-22, 07:14 PM
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I have power at the delay relay.
 
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Old 11-26-22, 08:04 PM
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Yes,26V
 
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Old 11-26-22, 08:26 PM
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I had someone come out yesterday for a diagnosis but I don't know how good he is,when he was "diagnosing" he arced something,not sure what but at the end he said the motor was bad.I replaced the motor already and it still doesn't work.
 
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Old 11-26-22, 09:32 PM
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Sorry PJMAX I didn't notice that you circled what you were asking about.Oh and thank you for all your input it has helped rule some stuff out as the problem! I think it is a transformer but not sure.The one above that is the delay relay.The thing right below the one you circled looks like a switch.The picture right below the time delay relay has a good view of that.
 
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Old 11-26-22, 10:04 PM
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The second picture in the "more pics" message #15 is the switch that is on the blower motor housing just below and behind the blower motor.
 
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Old 11-27-22, 09:24 AM
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What is that partially covered part number on that time delay relay?

You should be measuring 0 volts on that time delay relay when a demand is present.

You have proven that the relay is the problem.

Changing anything other than the relay is not going to fix the problem.

110 volts at those terminals proves potential voltage.
This proves that the cause is the relay.
110 to ground isn't the same as 110 across those 2 terminals.

If the relay was closed, as it should be when demand is present, then you would be on the same side of the load at both points.

Believe me, I've performed this test many times. Many, many times.

Shorting those two wires will provide power to the motor.
 
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Old 11-27-22, 10:16 AM
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Wow that is an expensive little Camstat relay.
I would search your part number and not necessarily use this example.


Your wiring diagram reminds me of Lennox and Trane and Bosch diagrams.
They don't show every wire. The 2 low voltage wires aren't shown in the diagram.


 
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Old 11-27-22, 10:21 AM
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Should I short the green wires or the orange and black wires?
 
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Old 11-27-22, 10:24 AM
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Black and orange wires are shorted when the relay closes as it should during normal operation.

Shorting the green wires cooks the transformer. you don't want that.
 
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Old 11-27-22, 11:04 AM
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No I don't want that! It says CAM STAT S106--1A-55-60C on the time delay relay.Can I short those wires together over night safely?I can pick one up tomorrow!And thanks a lot for all of the help I really appreciate it!
 
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Old 11-27-22, 11:30 AM
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There is much info missing here. My first observation is the photo shows 4 wires on a time delay relay, but neither the furnace wiring diagram or the furnace schematic show a time delay relay. Also missing on the documents is the gas igniter and its interlocks. Is it possible you got wires mixed up? The schematic shows 2 wires going to blower motor. Your photo show at least 4 connections at the blower motor. You said you changed the blower motor. How did you identify the equivalent wires between old/new blower motors? What was old/new rating of the blower motor capacitors?
 
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Old 11-27-22, 12:28 PM
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Yes you can short them overnight if you can get a good secure connection.

 
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Old 11-27-22, 12:31 PM
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The diagram is still 10 times better than many Lennox heat pump and Bosch geothermal units that I see regularly.
 
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Old 11-27-22, 03:49 PM
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I have put the two wires together to test,Blower motor comes on,it works!I don't know when I can replace the part most of the supply places are closed today and the ones that are open can't get it until dec.or jan.and are very pricy almost $200! As for the motor wiring a motor just like the one in the picture was in it way before I moved in here and I put a motor just like that one in there maybe 10 years ago plus the one that I just put in this weekend and they all worked.
 
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Old 11-27-22, 04:49 PM
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Houston204. shorting wires may be OK for a tradesman who has knowledge of what a component's function is in a circuit, but usually it is a disaster for a DIY. By the way, what will shut off the blower motor when the t'stat is satisfied and the time delay contacts are jumpered?
 
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Old 11-27-22, 05:20 PM
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That's a good point. If the jumper connection is loose the connection can get hot. I would cut the wires and put a wire nut if I didn't stock Y connectors.


Running the fan continuously can become an issue in cool mode but not a major issue. Higher humidity.
I have done this on beeper calls a few times.
 
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Old 11-27-22, 06:00 PM
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I do know a little about electricity,Not an expert by any means and that was the first thing I thought of,I figured I could turn it on and off manually.I have already put together a kind of jumper with a switch and wires to extend the switch far enough to reach the thermostat so I can turn the switch off from there after I turn down the thermostat and the burner goes out.I know that it sounds like a pain in the ass but I have an 85 year old mother that lives here and she can't live without a furnace so I can stay up and turn the heater on and off for a few nights!

 
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Old 11-27-22, 07:14 PM
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I'm not sure why you would need to stay up if the gas still cycles with demand.
 
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Old 11-27-22, 08:07 PM
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The blower seems to stay on after the burner goes off.Wont it just blow cold after that?Thank you for all the help/info,it helped save me a lot of cash and headaches.Everybody I called wanted to charge me thousands of dollars which I do not have.I am going to call the place that sent the guy out that diagnosed it as the blower motor,they charged me over $100 to come out to give me the wrong info.
 
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Old 11-27-22, 08:51 PM
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Camstats are not very common anymore. They were more common when I started in the field a long time ago.
I recommend getting a carbon monoxide detector along with that new Camstat.
 
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Old 12-11-22, 12:43 AM
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That is great news. I'm happy to have helped.
If you ever find the need to jumper 2 spade connectors again these are the adapters that I use...


 
 

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