Carrier 42QFD048D8S Service Manual page 109

TS11-L: Top temperature protection of compressor diagnosis and solution
Description: If the sampling voltage is not 5V, the LED will display the failure.
Recommended parts to prepare:
• Connection wires
• Outdoor PCB
• Over load protector
Troubleshooting and repair:
Check if the air flow system
of indoor and outdoor units
are obstructed?
No
Turn off the power supply and turn
it on 10 minutes later.
Yes
Check if the temperature of
compressor Top
Is more than 90℃？
Yes
Check if the refrigerant
system
is normal?
Yes
Replace the outdoor control PCB.
Clear up the air inlet and outlet or the heat
Yes
exchanger of indoor and outdoor units.
Check if all the connection, especially
No the connection of OLP (Over Load
Protector) sensor is good.
Measure
between the two ports of
the OLP. Is it zero?
No
Repair the refrigerant
system .
 Troubleshooting
Yes
the resistance
No
Yes Replace the outdoor control PCB.

No Correct the connection.
Replace the OLP.