Coleman 8900 Furnace Fan Won't Come On

Questions about repairs and parts for Coleman furnaces, air conditioners and heat pumps for manufactured homes. Click here for Coleman parts.

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Sun Feb 18, 2007 10:31 pm

Furnace lights but turns off when fan fails to operate. Replaced the 2 wire (RED & WHT) T stat with a Honeywell 2 wire HEAT ONLY T stat but it doesn't have a FAN CONTROL switch to check the fan in MANUAL to eliminate the FAN SWITCH in the furnace. Can anyone tell me where the FAN SWITCH is in the furnace? The wire colors don't quite match up with the schematic's wire colors so I can't trace them back... Thanks...Monty


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Sun Feb 18, 2007 10:32 pm

Complete model number please. I cannot locate a 8900 series unit. Please check your model number and brand name again and repost.
hvac1000

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Sun Feb 18, 2007 10:34 pm

OK...
It is my older sister's mobile home...a honey-do if you will...
Coleman 8995 Upflow Forced Air Furnace
Model 8995E676
Serial No. 950345386
Btu/Hr Input 95,000

While I'm unindating you with all this, I do have another question. Is the furnace on all the time when the T-stat is calling for heat all the time(24V) or does the furnace cycle on and off with the blower continuously blowing the air?
I shorted the FAN SWCH and the fan stays on, but the furnace eventually goes out. Didn't short the LIMIT SWCH cause the furnace does come on initially which shows that at least initially, it's working. Same for the CENTRIFIGUL SWCH. What the heck is a ROLL OUT SWCH? Anyway, same for it... Thanks again...Monty

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Sun Feb 18, 2007 10:34 pm

I do not believe this is a mobile home furnace. In fact the picture tells me it is not designed for a mobile home. There is a big difference between a furnace for a mobile home and one for a stick built home. We only have information here for mobile homes but I will tell you what I believe to be the problem.

The furnace has an automatic fan switch. The picture you sent will not blow up good enough to get a clear look at the unit but if you look at the top you will see a box that says hot. Below that and to the right there is a sensor/temp disc. This could be the fan control on this unit.

I must tell you that having this furnace in the mobile is not a good idea and also it violates HUD and all other code requirements. If there is a fire I doubt if the insurance company will pay off. I am just mentioning this information as a friendly gesture and something for you to think about. BTW parts for this unit may no longer be available but usually a crafty repair person can find something that will work.

hvac1000

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Sun Feb 18, 2007 10:34 pm

Roll out switch= A switch designed to prevent a fire if the draft or draft inducer stops working and the fire or heat rolls out of the front of the unit or vestibule area.

The fan will run all the time but the gas valve should cycle with the operation of the thermostat. You can test for this by just turning the thermostat up or down and checking the results.

hvac1000


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Sun Feb 18, 2007 10:35 pm

The furnace has an automatic fan switch. The picture you sent will not blow up good enough to get a clear look at the unit but if you look at the top you will see a box that says hot. Below that and to the right there is a sensor/temp disc. This could be the fan control on this unit."
The ladder schematic calls this part a Manual Reset Limit Switch that gets 24VAC from the t-stat and supplies coil voltage for the HEAT RELAY and is physically mounted below and to the right of the box with 'HOT' on the front and it has a red reset button on top which I have toggled a few times. I guess if it's intermittent, it could be the problem...although the furnace does light, but just won't stay on...Thanks for your help...Monty

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Sun Feb 18, 2007 10:35 pm

No I do not believe the limit is the problem. I thought that part was the limit because I cannot read the drawing or really see the furnace parts from the pic you sent. You need to find the fan switch . That will prevent the blower from turning on if it is defective.

hvac1000

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Sun Feb 18, 2007 10:36 pm

This pic shows I have the FAN SWITCH (the one on the right) quick-disconnects(one from the XFRMR fed by the BLOWER DOOR SAFETY SWITCH & the other from the BLOWER RELAY) shorted with a paper clip enabling the fan to run in case that was the culprit but the furnace still turns off even though the blower is still working...
The LIMIT SWITCH is located left of and next to the FAN SWITCH with the large orange wires still attached...

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Sun Feb 18, 2007 10:36 pm

If you jump the fan switch all it will do is cause the blower to run all the time. This will keep you warm and the heat will blow but you should replace the fan switch. Since you found the fan switch take it out and blow off the dust. There should be some numbers on it that you can use to get a new one.

hvac1000

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Sun Feb 18, 2007 10:36 pm

So...does the furnace burner cycle on & off with the blower on when the t-stat is calling for heat or should that burner stay on all the time until the t-stat hits hi-limit? I can't tell if the burner is shutting off because of a problem or because of it's normal duty cycle on & off...
Thanks for all the help.

Monty

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Sun Feb 18, 2007 10:37 pm

So...does the furnace burner cycle on & off with the blower on when the t-stat is calling for heat

The burner will cycle on and off with the thermostat. Since you jumped the switch the blower will run all the time. This set up will work until you get a part.

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Sun Feb 18, 2007 10:37 pm

So any time that t-stat calls for heat (supplies 24VAC via the WHT wire from t-stat,)the burner should be on during that time and not toggling on and off? Just want to make sure there is not another problem causing it to cycle on & off or is that just the duty cycle set by mfr?

Monty

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Sun Feb 18, 2007 10:37 pm

No duty cycle.Burner controled by T-stat. There are limit switches etc that will open the T-stat circuit if a problem happens.

hvac1000

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Sun Feb 18, 2007 10:37 pm

Now when you say "Burner controled by T-stat.", are you saying as long as the t-stat is supplying 24VAC (room temp < t-stat temp), that burner will be on? Cause if that's the case, I still have a problem since the t-stat is set to 80 degrees and the room is around 60 degrees and after several minutes, the burner goes off. I've never paid much attention to whether or not it comes back on again automatically after some time.

Monty

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Sun Feb 18, 2007 10:38 pm

If that is the case you have another problem. At this time I am going to recommend you call a professional for on site service at the home. Unfortunately I can no longer be of assistance after exhausting the all the possibility's we have discussed. This unit really needs a professional who is there to test all the components of the furnace and track down the problem areas. I would rather see you call a pro so your furnace will operate safely. Sorry.

hvac1000

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