Fault codes covered
32-15, 32-55
Exceeding soft and hard low pressure limits result in code 32-15. The soft low pressure limit can be exceeded for up to 2 minutes before code is generated, while exceeding the hard limit immediately results in code 32-15. Low pressure limits are compressor and rpm dependent, but 30psi and 15psi are typical. 4 occurrences of code 32-15 result in a 2-hour lockout. Note: AEM will attempt to mitigate low pressure by adjusting system operation. This fault will only be set if system operation cannot be modified quickly enough to prevent exceeding hard and soft limits. A single occurrence of fault will result in 5-minute time delay followed by attempted restart if demand is still present.
Low pressure conditions can occur from multiple causes: Blockage in liquid line, stuck TXV or EXV, no airflow across evaporator, low system charge. Low ambient temperatures will increase diagnostic sensitivity to contributing factors above. Check pressure drop of liquid line at condenser and evaporator, confirm airflow across evaporator, and confirm system charge is correct. Replace EXV/TXV if necessary.
Source: ACHPVSR454-02SM troubleshooting pages.