Troubleshooting
18 Troubleshooting
18.1 Unit Troubleshooting
NOTICE
The troubleshooting information provided may reflect a fault
that could have one or more causes and one or more solutions.
Check each cause and adopt a “process of elimination” and/or
verification of each before making any conclusion.
NOTICE
If troubleshooting a system that is low on refrigerant due to a
system leak, DO NOT simply add refrigerant. The leak must be
found and repaired per F-Gas regulation.
Faults may be indicated by the UPM LED Status Indicator or a
remote device with a malfunction light. Refer to section
12
Safety Devices and the UPM Controller Overview starting on
page #25.
18.1.1 Online Help Resources
For FAQs, videos, service bulletins, and more, visit our Service
and Su
pport web page at www.boschheatingcooling.com/
service or use your cell phone to scan the code below.
Unit Troubleshooting
Problem Possible Cause Action
Entire unit does not
run
Power Supply OFF Apply power, close disconnect
Blown Fuse Replace fuse or reset circuit breaker. Check for correct fuses.
Voltage Supply
Low
If voltage is below minimum voltage specified on unit data plate, contact local power company.
Thermostat/
Controller (DDC)
Set the fan to “ON”, the fan should run. Set thermostat to “COOL” and lowest temperature setting, the
unit should run in the cooling mode
(reversing valve energized). Set the unit to “HEAT” and to the highest temperature setting, the unit
should run in the heating mode. If neither the blower or compressor run in all three cases, the
thermostat could be miswired or faulty. To ensure it is a miswired or faulty thermostat, verify 24 volts
is available on the condensing section low-voltage terminal strip between “R” and “C,” “Y” and “C,” and
“O” and “C”. If the blower does not operate, verify 24 volts between terminals “G” and “C” in the air
handler. Replace the thermostat if defective.
40 |
EC Series Heat Pumps — 8733841499 (2024/05)
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