Bosch QV Series Installation, Operation And Maintenance Manual page 37

QV Series Heat Pumps
Problem
Cooling
NO
COMPRESSOR
OPERATION
BUT FAN RUNS
(CONTINUED)
X
QV Series Heat Pumps
Unit Troubleshooting
Mode Check
Heating
Is the Fault
LED
X blinking two
(2) times?
Is the Fault
LED
X blinking three
(3) times?
Is the Fault
LED
blinking four
(4) times?
Subject to change without prior notice
Possible
Cause
Low pressure Check water valves and/or pumps for
fault—No or proper operation. Check for water coil
low air flow blockage.
75 Unit Check for proper flow rate and water
temperature, but low-water-side temp
rise in cooling.
Low pressure Check refrigerant pressure with a
fault—Low gauge set.
refrigerant
Freeze fault, Check water valves and/or pumps for
water coil— proper operation. Check for water coil
No or low blockage.
water flow
Freeze fault - Check water temperature - is it
low below 40° F entering? If heat pump
water is connected to a closed loop with
temperature antifreeze check that the "FREEZE 1"
resistor on the UPM board has been
cut to set the unit to antifreeze mode
(see UPM features on page #27).
Freeze fault - Check refrigerant pressure with a
low gauge set.
refrigerant
Condensate Check condensate pan for high water
fault—Poor level. Check drain line for blockages,
drainage double trapping or inadequate
trapping.
Condensate Check air filter and return air
fault—blocked duct work for blockage. Check that
return air there is adequate space
between the return air opening and
walls or other obstructions on free
return applications.
Troubleshooting | 37
Action
8733829041 (2021/07)