Guardian PowerVent Training Manual SVC900; Rev 1
Page 21
HOW TO CHECK THE BLOWER MOTOR
The blower motor on the Guardian PowerVent is responsible for all fresh combustion air
entering the combustion chamber. There are two different blowers and may not be interchanged
between products. The short blower goes on only short models and the tall blower and goes on
the tall models. The tall blower is more robust than the other because is needs more power to
vent the combustion by-products on the taller models. Interchanging the two motors will cause
erratic behavior and lockouts. Of special note is that the blower motor mounting gaskets must be
in good condition to prevent exhaust gases from escaping into the living space where the water
heater is installed.
In normal operation, the controls check for a closed vacuum switch within 12 seconds before
starting the pre-purge time. The vacuum switch measures the vacuum created by the blower and
verifies the blower is operating at speed. The control attempts to verify the vacuum switch is
open first. If the vacuum switch is not open, the control attempts to open the switch by cycling
(turning off, then on) the blower motor. After 5 cycles (attempts), the control will lockout. LED
indicator will flash 3/1. This means the vacuum switch failed to open.
When the blower is turned on, the control insures it that the vacuum switch is closed before
continuing with the ignition sequence. If it cannot force the switch to close by cycling the
blower, it will indicate this failure. LED indicator will flash 3/3. Three potential causes of these
faults are the vacuum switch is damaged, the blower motor is damaged, or there are venting
problems.
Figure 5 – Blower Motor
1. Verify unit is plugged in to a 120VAC source.
2. Disconnect the PVC vent pipe temporarily.
3. Turn unit on at the on/off switch at the blower
motor.
4. Blower motor should operate. Check flash code
on the gas valve. The LED should have a constant
fast flash. If the blower motor comes on and you
get main burner, there is a problem with the
venting or a vent restriction.
5. If the blower motor does not operate, check for
120VAC at the on/off switch.
6. Remove the switch cover and measure for
120VAC at the bottom of the switch. If 120 VAC on the bottom, then turn switch to on
and check for 120VAC at top of switch. If 120VAC at top of switch, then verify 120VAC
at the red #3 wire on the control valve; then verify 120VAC on the yellow #5 wire.
7. If you have 120VAC at the yellow #5 wire, replace the blower motor.
8. If you do not have 120VAC at the yellow #5 wire, replace the control valve.
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