Have an older Coleman mobile home furnace (Mdl 8665D766). Both blower fan and booster motor work fine; however, during heating, booster motor will keep constantly running after system cycles through

SOURCE: Heater blower motor cycles on and off (frequently). I have a class 2 LR95329 Honeywell Thermostat

I had the same problem with a Coleman. The problem is the blower relay. You can find this at http://mobilehomerepair.com

SOURCE: Coleman Presidential II mobile home

Is this furnace standing pilot or electronic ignition. If standing pilot i would check furnace filter then the thermastat. To test themostat first turn power off to furnace. Take thermostat off wall and take wires labled R & W and connect them together. If you have electronic ignition I would start with cleaning the flame sensor with steel wool or wire brush.If you have and more questions i will be glad to help.

SOURCE: main blower stays on, burner fan on intermitantly,

All gas furnaces have a fan control of some sort. Either a mechanical fan control where there is a temperature probe that reaches into the heat exchanger compartment thru a hole in the panel that separates the control part of the furnace(this would be the front of the furnace where all the controls are) from the heat exchanger. This type of control is either a small black plastic control about 4 inches by 2 inches and about 1 1/2 inches thick secured to the panel with 2 screws. Or it is a slightly larger silver colored control that should have a pull off cover. It may say Honeywell on it. Either way the control will need replacing.
The other type of fan control is a solid state control board. This will most likely be located in the indoor fan compartment. It should be located under a covered control box. The box with all the wires going into it. This board will also need to be replaced if your furnace uses this type of fan control. You will need to bring your furnace model and serial number to a dealer that sells your brand of furnace or go online to a parts dealer that carries parts for your furnace. Hope I was of help to you! Good luck!

SOURCE: Coleman model 296OC666 vent blower will not cycle

Hi,
Your problem is with the relay on the circuit board that controls the vent blower. This relay has welded the contacts making the blower run continuously.
The relay is not replaceable so you will have to order a new control.
The part will be the main control that all the t-stat wires hook too.....

I hope that this will help you to solve your problem!

Thanks for using Fixya!!

Heatman101

SOURCE: Coleman furnace -- fan runs, ingniter won't light,

My furnace did not have a reset switch on that particular limiter. I unpugged the switch, it had 2 wires, waited 15 seconds or so and then plugged it back in . Turned the furnace back on and the limiter reset itself.