Safety Circuit Voltage Trace
WARNING
115 volt potential exposure. Use caution making voltage checks to avoid
personal injury.
Safety Circuit Voltage Trace
14
Note: This procedure assumes a cold tank.
Step 1. Remove three screws (Phillips screw driver) from control access cover on blower and remove
cover.
Position gas control switch to the “ON” position and adjust the thermostat dial to call for heat. Is there 10 to 13VAC between the red wire leading to the blower temperature switch and the green ground wire? Blower must be running during this voltage check (see photo 15).
Y
N | Is LED on gas valve flash- Y |
| |
| ing the “heartbeat” code |
| (alternating bright/dim)? |
N
Verify 115VAC to gas con-
trol (see page 41).
N
No voltage from gas control.
Call for technical support.
Determine cause of blower temperature switch activa- tion and correct.
Is there 10 to 13VAC between
the yellow wire leading from the N pressure switch and the green ground wire (see photo 27)?
Y
N
Do you hear or can you see the igniter sparking?
Y
Safety circuit voltage is OK.
If burner does not light, ob- serve LED flash code on gas control and refer to trouble- shooting section on page 17.
Is there continuity through
the blower temperature switch (see page 31)?
Check igniter/sensor (see page
22). Is igniter/sensor OK?
Correct igniter/ sensor problem
Green ground wire
Red sire leading to blower temp. switch
Yellow wire leading from pressure switch
YCheck for loose or broken 
wire connection at switch
terminals.
Y
Faulty cord set or gas control
15
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