FAUL
T CODE THUMBNAILS –
PAGE
F 3
FAUL
T CODE THUMBNAILS –
PAGE
F 3
Heater System Solving Guide
Fault Code Thumbnails AO Blower V
acuum Switch – F
ailed Open
F
AULT
C
ODE
T
HUMBNAILS
AO B
LOWER
V
ACUUM
S
WITCH
– F
AILED
O
PEN
UHS
IDL2
IDL
AO
B
LOWER
V
ACUUM
S
WITCH
– F
AILED
O
PEN
If the blower vacuum switch opens unexpectedly during operation, the
heater will shut down and attempt to re-light if there is still a call for
heat. If the blower vacuum switch does not close after the blower starts,
the control will stop the ignition trial & go into lockout. The blower will
continue to run for post-purge.
Automatic reset is immediate after the switch closes.
P
ARTS
T
HAT
M
AY
B
E
N
EEDED
• Blower
• Control Module/Ignition Board
• Blower Vacuum Switch
• Gray Vacuum Tubing
D
IAGNOSTIC
S
EQUENCE
A. Check for faulty vacuum switch
tubing
and replace if necessary.
B. Check for faulty vacuum switch
wiring
or
connection
. Wire harness
terminals must be securely fastened to spade terminals on vacuum switch.
C. Check for faulty blower
wiring
or
connection
. Plug on blower must be
securely fastened to control module.
D. Check for defective vacuum switch by disconnecting blower plug
from control module. Measure resistance across blower windings.
Winding resistance across lead should be in the following range:
IDL:
Black to White 30-45 ohms
Red to White 90-130 ohms
IDL2:
Black to White 10-14 ohms
Red to White 18-22 ohms
UHS:
Red to White 8-9 ohms
If measured values vary substantially from these values,
the blower is defective and should be replaced.
E. Check for a defective blower relay by disconnecting blower plug from
the control module. Place heater in Pool or Spa mode. Lower set point
temperature to generate call for heat. During pre-purge period, measure
for 120VAC across pins 1 and 2 (UHS & IDL2) or L1 & IND low (IDL).
If 120VAC is not present, the control module relay is defective, which
means the control module must be replaced.
F. If the above steps do not resolve the problem (the error still exists),
the vacuum switch is defective and must be replaced.
