loaddriver
02-01-2006, 09:02 PM
I've replaced just about every major component in a
couple of dozen York downflow furnaces. I don't know
whether I've been lucky or just very methodical, but
I've never had any problems until today.
A neighbor tells me his York furnace (model no. P3CCD12N0
7601A) is completely dead. He's got a basic Honeywell
mercury switch thermostat, but its only a couple of years
old. The switch checks out good and I'm reading 24 VAC
at the thermostat control wires.
After several tests on this furnace its obvious that the
original White Rogers Ignitor Control Module is not
supplying 24 volts to the gas valve solenoid terminals.
I'm amazed that this module (50E47-070) lasted for almost
thirteen years!
I purchased the replacement for the entire 50E47-XXX series.
Model no. 50E47-843. It's the one with the card port and
six program keys that allow you to set the trial ignition
time, retries, prepurge, and igniter warm up times.
Before I remove any complex part I always take some
graph paper and make a quick drawing of all the original
connections, wire colors, termimal numbers or letters, etc.
Maybe you veterans never forget anything, but I feel a
whole lot better hooking up the new module with my diagram
of the old unit. The chances of making a wiring error are
almost reduced to zero.
With the new control module in place I'm still not getting
24 volts at the gas valve. In fact, the LED is not lighting up
at all! With this new module the LED can be used as a
diagnostic tool to determine if you wired the module
correctly, plus several other conditions.
I did check the solenoid coil for any shorts. Its ok.
I also checked the main house breaker for the furnace and
the emergency power cutoff wall switch. No problems in
either case. The furnace transformer checks out good.
The contactor (relay) that controls the blower is ok too.
I always keep a little custom made clamp in my toolbox
that keeps the plunger switch depressed when I'm testing
the system. Its very easy to forget that this switch
opens the second you remove the furnace cover!
I tried switching the two "MV" wires that supply power to
the solenoid. I am getting 120 VAC at the "L1" module
terminal. Even though its not needed with this furnace,
I used the jumper wire provided with the module and
connected "L2" to ground. This wire is used as a neutral
power supply connection.
I'm completely stumped. The answer is probably staring me
right in the face but I don't see it. If there is something
obvious that I haven't tested please point this lost soul
in the right direction!
couple of dozen York downflow furnaces. I don't know
whether I've been lucky or just very methodical, but
I've never had any problems until today.
A neighbor tells me his York furnace (model no. P3CCD12N0
7601A) is completely dead. He's got a basic Honeywell
mercury switch thermostat, but its only a couple of years
old. The switch checks out good and I'm reading 24 VAC
at the thermostat control wires.
After several tests on this furnace its obvious that the
original White Rogers Ignitor Control Module is not
supplying 24 volts to the gas valve solenoid terminals.
I'm amazed that this module (50E47-070) lasted for almost
thirteen years!
I purchased the replacement for the entire 50E47-XXX series.
Model no. 50E47-843. It's the one with the card port and
six program keys that allow you to set the trial ignition
time, retries, prepurge, and igniter warm up times.
Before I remove any complex part I always take some
graph paper and make a quick drawing of all the original
connections, wire colors, termimal numbers or letters, etc.
Maybe you veterans never forget anything, but I feel a
whole lot better hooking up the new module with my diagram
of the old unit. The chances of making a wiring error are
almost reduced to zero.
With the new control module in place I'm still not getting
24 volts at the gas valve. In fact, the LED is not lighting up
at all! With this new module the LED can be used as a
diagnostic tool to determine if you wired the module
correctly, plus several other conditions.
I did check the solenoid coil for any shorts. Its ok.
I also checked the main house breaker for the furnace and
the emergency power cutoff wall switch. No problems in
either case. The furnace transformer checks out good.
The contactor (relay) that controls the blower is ok too.
I always keep a little custom made clamp in my toolbox
that keeps the plunger switch depressed when I'm testing
the system. Its very easy to forget that this switch
opens the second you remove the furnace cover!
I tried switching the two "MV" wires that supply power to
the solenoid. I am getting 120 VAC at the "L1" module
terminal. Even though its not needed with this furnace,
I used the jumper wire provided with the module and
connected "L2" to ground. This wire is used as a neutral
power supply connection.
I'm completely stumped. The answer is probably staring me
right in the face but I don't see it. If there is something
obvious that I haven't tested please point this lost soul
in the right direction!