On Tue, 10 Dec 2013 16:54:27 +0000, Danny D'Amico wrote:
LESSONS LEARNED on my Payne 394JAW propane furnace this week:
Voltage between R & C should be 24VAC.
- Red = 24VAC power (sometimes called RH, for Red Heat, RC for Red Cold)
- C = common (often blue, or black), usually not switched
The typical color code is:
- White = heat
- Green = blower
- Yellow (sometimes blue) = Compressor
- O = Orange (heat pump)
A typical test would be:
- Connect R to W to tell the furnace to supply heat.
- Connect R to Y to tell the system to supply cooling.
- Connect R to G to tell the system to operate the fan.
Most common problems:
0. It's (usually) not the thermostat
1. Sticking 3-wire pilot assembly (common, low stage, high stage)
2. Power to the two-stage gas valve (which is only on 4 to 7 seconds)
3. Spark igniter (high voltage comes out to light pilot)
4. Gas valve (sticking or blown solenoids)
5. Fan control board (often a relay sticks or won't turn on)
7. 3A fuse on the blower circuit board
8. One of the safety mechanisms has tripped
The thermostat "calls for heating" by connecting Red to White.
Power goes from the 24VAC Transformer to the Fusible Link to the
Limit Switch to the Vent Safety Shut-off Switch to the Lockout
Timer to the pilot ("pick" & "hold" gas valves), enabling propane
gas to begin flowing in the pilot.
Power also flows to the high-voltage igniter, which clicks a few times
to ignite the pilot flame.
About 60 seconds after the pilot lights, the safety pilot switches its
contacts and energizes the main valve portion of the gas valve.
About 10 seconds later, the main gas valve opens, and the main gas is
ignited by the pilot flame.
About 75 seconds after the pilot lights, the fan control board activates
the blower on low speed.
When the thermostat "is satisfied", the connection between R & W is broken.
Gas is immediately stopped to both the pilot and main burners.
The blower continues for about 100 seconds.
a) If the furnace overheats, the Limit Switch opens.
b) If the furnace overheats in the vestibule, the Fusible Link opens.
c) If the furnace overheats in the vents, the Vent Safety Switch opens.
d) If the pilot doesn't light, the Lockout Timer shuts down the system.
e) If the door is opened, the 120VAC door switch turns off the power.
These are the thermostat connections:
This is the "3-wire pilot assembly":
This is the high-voltage ignitor:
This is the "gas valve" (set up for propane):
This is a fusible link, vent switch, & the "lockout timer":
This is the limit switch:
This compartment holds the fan-control PCB:
This is the terminal set from the thermostat (and elsewhere):
This is the 3 Amp fuse for the fan-control PCB:
This is the "fan control" PCB:
This is the 120VAC door safety switch:
This is the on/off switch for the gas, which remains on:
This is the on/off mechanism (pull the plug) for the 120V power:
This is the 16x25x1 3M filter:
This is the schematic printed on the inside of the door panel:
This is another smaller schematic above that big one on the door panel:
And, this is on the outside of the door, for the electric pilot:
This is a furnace operational and troubleshooting manual::
This is the burner running and heating up the house:
- Check the air filter & clean with water monthly.
- Clean & lubricate blower wheel yearly.
- Clean the pilot area and clean the sensing probe yearly.
- Lubricate the motor with 20-weight oil every 2 to 5 years.
- Clean heat exchanger with brush & vacuum when necessary.
Thanks to all of you, this one furnace is not only working, but,
it's finally starting to make sense how it works.
Your help in this endeavor was/is much appreciated.