wrote in message
oups.com...
Thanks for the help again Turtle.
I can run the fan in ON position and it keeps running continuously
without stopping. As a matter of fact, that is how I have it now until
the service tech arrives. I also changed the filter last month.

The diagnostic light on the ECU remains OFF, so the ECU is not noting
any problems with its sensors.


Tony


This is Turtle.

This still does not prove anything.

#1 first when you turn the thermostat to cont. fan mode it shifts the motor to a
higher speed winding and a motor can be burnt up on heating / low or med. speed
and still run fine on high speed for cooling.

#2 The heating mode of the furnace relay board or relay system will run low or
medium speed to run the heat and high speed for cooling mode. You can have bad
bearing on a motor and start cutting out on low or medium speed but run fine on
high speed for you have more horse power on high and can over come the drag of
the bearings. Direct drive blower motor have different house power on each speed
as here : [ High Speed 1/2 H.P. 1075 R.P.M.'s ] [ Medium 1/3 H.P. 975 R.P.M.'s ]
[ Low Speed 1/4 H.P. 875 R.P.M. ] .

#3 Most all older blower motors have 3 or 4 speed types have completely
different motor built into them. A 4 speed motor has 4 different motors built
into it. You can burn up 1 or 2 or three of the speeds and still have 1 or more
that will still work fine. So your testing just showed that high speed of your
furnace is ok but never looked at heat speed or medium speed as it being good or
not.

#4 Now you have high speed running for the tech to see but when he gets there ,
tell him to check the problem speed of medium or the low speed set for heating.

#5 Now you still don't know what it is but you can use the high speed to heat
with till he gets there.

TURTLE