00017
Carrier Transicold
Critical
Alarm 17 – High Compressor Discharge Temperature (CDT)
Carrier Transicold alarm code 17 (AL17) triggers when Compressor Discharge Temperature (CDT) climbs above the safety threshold — typically 310°F (154°C) on Vector, X4, X2 and Supra reefer units. The Advance controller shuts the unit down to protect the compressor from thermal breakdown of oil, valve plate damage, and burned windings. AL17 almost always points at a refrigerant-side or airflow problem, not the compressor itself.
Possible causes
- Low refrigerant charge — insufficient mass flow to cool the compressor head
- Blocked or clogged filter drier restricting liquid flow
- Stuck-closed or misadjusted TXV starving the evaporator
- Dirty condenser coil or failed condenser fan (high compression ratio)
- Non-condensable gases (air) in the refrigerant circuit
- Failed or drifted CDT sensor giving a false-high reading
- Compressor internal valve leakage (worn discharge reeds)
- Suction service valve partially closed after PM work
Recommended actions
- Read live CDT, suction pressure and discharge pressure from the controller — high CDT with low suction pressure = starved evaporator (charge or TXV).
- Weigh the refrigerant charge against the unit's data plate; leak-check and recharge if short.
- Change the filter drier and re-check — a plugged drier is the #1 cause of AL17 in the field.
- Verify the condenser coil is clean and the condenser fan turns the correct direction at full RPM.
- Recover a small sample and check for non-condensables — evacuate and recharge if present.
- Test the CDT sensor at ambient: ~86 kΩ at 77°F (25°C). Replace if resistance is off or open.
- Check TXV superheat at the evaporator outlet; adjust or replace if superheat is > 12°F.
- If mechanical damage is suspected, do a compressor efficiency test (pump-down / pressure ratio) before condemning the compressor.
Can't find your code? Talk to an expert
$150
One-on-one phone session with a Low Temp refrigeration tech. Emergency temporary assistance only.
Other Carrier Transicold codes
Need a professional diagnosis?
Low Temp Service — refrigeration experts in Florida.