T960_O or T971_O: Compressor Lube Protection
The VSODC will not display any fault
The Drive LED's will not indicate anything
When the compressor sump thermistor sees a temperature below saturated suction temperature (Suction pressure converted to a temperature), The compressor slows down incrementally, and may go to lowest speed but will not shut off. Once the sump temperature increases to Suction Saturation Temp plus 10 degrees, is allowed to increment at the same rate as it was decremented. If the unit was running a reduced RPM for more than an hour, it is cancelled and allowed to run normally, for up to 5 minutes, where it can happen all over again.
- Check to make sure the suction line thermistor at the indoor coil is secure to the line if this occurs in cooling mode. If it occurs in heating mode, make sure outdoor suction thermistor is secured properly.
- Check accuracy of suction transducer and thermistor.
- Check operation of EEV's. Make sure stator is pressed firmly onto EEV valve body.
- Check accuracy and secure mounting of compressor sump thermistor.
