Diagnosis For Anti-High Temperature, Overload Protection - Carrier 38GRQB12-3 Service Manual

4. Diagnosis for anti- high temperature, overload protection (AP1 below is control board of the outdoor unit).
Main detection points:
S If the outdoor ambient temperature is in the normal range
S If the indoor and outdoor fan is running normal
S Are the units clear of dirt and debris?
Malfunction diagnosis process:
If the outdoor ambient temperature is
High temperature,
overload protection
higher than 127 ºF?
No
After the unit
de-energized for 20min
Outdoor unit coils clean?
No
Do the indoor and outdoor
fan work?
Y
Yes
Replace
control board
AP1
End
Fig. 40 – Troubleshooting
Yes Above operating envelope
Y
Yes Clean coils
1. Check if fan terminal
OFAN is connected well
No 2. Test if resistance value
of any two terminals is less
than 1k with ohmic meter
Replace fan
capacitor C1
Replace
outdoor fan
37