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D_E_Bishop's avatar
D_E_Bishop
Explorer
Jan 22, 2020

Thermostat Fan Speed switch doesn't work, LONG

I have a '02 Winnie Adventurer with a Suburban SF35 furnace and a Coleman residential central AC/Heat pump unit, controlled by a Coleman-Mach Thermostat. Last week we were dry camping in Quartzsite Arizona and experiencing overnight temps in the low 40's to mid 30's. The rear bedroom/bath area has 3 furnace registers, the kitchen/dinette area two registers and the cockpit area one. The AC has numerous registers in the ceiling.

Because we were dry camping for 10 days we relied mostly on the furnace for heat and there is very little air movement in the cockpit. One morning it was especially cold, about 37 degrees and knowing the AC/Heatpump would not be very effective, I tried it anyway. The air from the heatpump was barely above body temp but as I later learned, the two appliances are tied together so that if the air temp and the temp setting on the termo are more than 5 degrees apart, the furnace will start and run until the the room temp reaches the set temp of the thermo and then both the heatpump and the propane furnace shut off.

What was odd to me was the furnace came on at a very high speed, high enough that as my wife walked over floor register, her nightgown did a MM thing by blowing up around her knees. It had never blown that hard before and the air temp in the cockpit/dinette areas are normally 5 to 7 degrees cooler than the bedroom/bath areas. The thermostat is in the hall separating the bedroom/bath areas from the dinette/cockpit areas. When the thermo shut down both units, the temps in the dinette/cockpit area were the same as the bedroom/bath area.

The thermo allows for heat, AC and heat pump and for fan only at HiSpeed or LowSpeed and heating/AC at either HiSpeed or Low Speed. The "fan only" function does not work at all and we've had this rig about 2.5 years and the furnace has never had much airflow. It is opvious that the floor duct is clear because the one time the high speed did come on there was as much airflow in front as in the back and it was enough to move the DW's nightgown around.

How do I trouble shoot the fan speed control. None of the schematics I could find show a speed control wire on the thermostat. Getting help from AirEx is neigh impossible and I am not a member of any of Winnie's consumer groups. Normally I can find installation instructions to find out what should be there or how things should work but this has me stymied. Anyone have any ideas?

Another important bit of information is that the RV is 45 miles from our house and so I can't just walk out to it and look for anything. Knoing what to look for , however, would be good to know as I will be out there at least by Saturday.

6 Replies

  • What was odd to me was the furnace came on at a very high speed, high enough that as my wife walked over floor register, her nightgown did a MM thing by blowing up around her knees.


    I don't know the cause, but this is the only way you should operate your furnace from now on.

    :)

    Steve
  • D.E.Bishop wrote:
    I'm sorry Doug but I'm not aware what you mean by the Coleman HP blower motor.


    This is your Main Basement AC. HP stands For Heat Pump. The basement AC has 2 motors. One motor is the outside Condensor fan motor. The other is the INSIDE whole house blower motor and this motor is the 2 speed motor. The wall tstat should have HI and LO fan speeds plus an AUTO setting. The Tstat has a HI and LO individual wires that goes to the Basement AC control board and is connected to the HI and LO inputs on the control board. When that HI or LO wire is energized, the control board then sends the signal to the HI or LO 120 wire on the Fan motor. Doug
  • The L.P. furnace, the one that blows out of the floor, only has one fan speed.
  • I'm sorry Doug but I'm not aware what you mean by the Coleman HP blower motor.
  • Quick response---The furnace only has 1 fan speed. It is NOT adjustable. The higher air speed must have been from the Coleman HP blower motor. Doug