American Standard Air Conditioner Error Codes — Meanings, Causes & Repair in Greater Vancouver

Seeing a fault code on your American Standard air conditioner? This guide explains what the most common American Standard air conditioner error codes mean, what’s safe to check yourself, and when to call HeatLand’s licensed HVAC technicians for American Standard air conditioner repair across Metro Vancouver and the Fraser Valley.

The codes below apply across common American Standard models (Platinum, Gold, Silver). Meanings follow American Standard’s documented fault codes — always confirm against your unit’s own manual, because exact wording can vary by model, control board and firmware.

How to read American Standard air conditioner error codes

American Standard communicating air conditioners (Platinum 20/18, Gold 17, and similar two-stage/variable-speed models) use the AccuLink / ComfortLink II control bus, which is the same platform shared with sister brand Trane. Faults are reported as numeric Alert Codes shown on the AccuLink color thermostat (AccuLink Platinum 1050 / Gold 950 / 850 / 824) as 'Err ###' or 'Error ###.##', and on the outdoor unit's control board (CDA / Charge Diagnostic Assistant on variable-speed units) as red Fault-LED flash patterns. Each numeric Alert Code maps to a CL2.xxx.xx alarm ID in American Standard / Trane service literature (e.g. Alert 79 = CL2.079, Alert 80 = CL2.080, Alert 89 = CL2.089). The highest-priority faults flash sequentially on the LED; cycle power to the outdoor unit to clear stored hard-lockout faults. Basic single-stage, non-communicating American Standard air conditioners (entry Silver-series models) have NO digital fault-code display and provide only a hard-wired condenser status LED – diagnosis on those requires a technician with gauges and a meter. Source: American Standard / Trane CL2 Alert Code reference tables and ComfortLink II / AccuLink Service Facts.

American Standard air conditioner error codes & what they mean

These are the American Standard air conditioner codes our Greater Vancouver technicians see most. Anything marked pro repair involves electrical, refrigerant, sensor or control-board work that must be done by a licensed HVAC technician — never open the indoor/outdoor unit or refrigerant lines yourself.

Code	What it usually means	Common causes	Safe to check yourself
18	24V Sensing Error / Control Fault (AC Sns Err / CTRL FLT, CL2.018). 24V is not being sensed at the Y1 input (J1 connector) of the outdoor control board, or the outdoor control board has an internal failure. Shown as Err 18 on the AccuLink thermostat pro repair	Missing or faulty Y1 (red wire) 24VAC signal reaching the outdoor control board; Loose or corroded low-voltage wiring at the outdoor unit J1 connector; Internal failure of the outdoor control / inverter board, sometimes caused by a line-voltage spike or static discharge	Confirm the thermostat is set to Cool with the setpoint below room temperature; Check that the outdoor disconnect and the breaker for the air conditioner are both ON; Try one power cycle: turn the AC breaker off, wait one minute, turn it back on, and allow several minutes for the system to re-establish
67	Temperature Sensor Fault – out of range, open or shorted (CL2.067). Covers the outdoor Ambient, Coil, Liquid, or External Outdoor Temperature sensor depending on sub-code. Shown as Err 67 on the AccuLink thermostat pro repair	Outdoor ambient, coil, liquid, or outdoor-temperature sensor open, shorted, or out of range; Damaged sensor wiring or a loose sensor connector on the outdoor control board; Failed temperature sensor (thermistor)	Try one power cycle of the air conditioner at the breaker and allow several minutes to clear
68	Defrost Fault, heat pump models only (Fault A / B / C, CL2.068). Defrost was terminated abnormally – on time-override instead of temperature, or on abnormal delta-T. Cooling-only air conditioners do not run defrost, so this applies to heat-pump versions of the platform pro repair	Heat-pump defrost sensor fault, low refrigerant charge, shorted coil sensor, or open ambient sensor (heat pump only); Reversing valve (SOV) stuck, or outdoor fan failure; Defrost repeatedly terminated on the 15-minute time override instead of temperature	For heat pumps, confirm the outdoor coil is not blocked by ice, snow, leaves, or debris and clear anything obstructing airflow around the unit; Try one power cycle at the breaker
79	Low Pressure Cut-Out (LPCO) Fault (CL2.079). The low-pressure switch has opened. Sub-codes cover a short lockout, a heat/cool lockout, and a hard lockout after the third trip in the same call (cycle power to reset). In cooling, suction pressure has dropped below the low-pressure limit. Shown as Err 79 on the AccuLink thermostat pro repair	System low on refrigerant charge (leak); Indoor airflow restriction in cooling (dirty filter, blocked return, dirty indoor coil); Low-pressure switch wiring open or shorted	Replace or clean the indoor air filter if dirty; Make sure supply and return vents are open and unobstructed; Confirm the thermostat is set to Cool below room temperature
80	High Pressure Monitor Fault (HPCO, CL2.080). The high-pressure switch (limit approximately 650 psig) has tripped. Sub-codes cover a short lockout, a hard lockout after 6 short-lockout events, and reduced-capacity operation. Shown as Err 80 on the AccuLink thermostat pro repair	Refrigerant overcharge; Outdoor fan failure or restricted outdoor (condenser) airflow – dirty or blocked condenser coil, recirculating hot air; Non-condensables in the refrigerant	Clear leaves, grass, dirt, and debris from around and on the outdoor condenser so air flows freely (do not open the unit); Make sure nothing is blocking airflow within about two feet of the outdoor unit; Replace a dirty indoor air filter and keep vents open
89	Equipment Missing / Configuration Fault (Config Fault, CL2.089). Equipment that was auto-discovered at startup is no longer reporting on the communication bus – the thermostat expected a component (such as the outdoor unit) and can no longer find it pro repair	Loss of communication to the outdoor unit or another component (open or shorted data line; ~16VDC on the bus instead of a healthy 12VDC); A breaker tripped or power lost to one piece of equipment; Loose communicating-bus connection at a component	Verify the breaker and disconnect for the outdoor unit are ON; Power-cycle the system at the breakers, wait one minute, and allow it to re-discover equipment
90	Excessive Communication Errors / System Comm Error (CL2.090). The AccuLink / ComfortLink II control bus has too many communication errors or lost the demand message; the thermostat is no longer reliably talking to the outdoor unit pro repair	Loose, open, shorted, or reversed-polarity communicating-bus wiring (the D and B / 1-2-3-4 data leads); Voltage out of range on the data line (12VDC indicates good communication; ~16VDC indicates a loss of communication); Failed control board on an indoor or outdoor component	Power-cycle both the thermostat and the equipment: turn the system off at the breakers, wait one minute, restore power, and give the system a few minutes to re-establish communication
91	System Communication Error / Loss of Heat-Cool Demand or System Clock (CL2.091). The communicating system lost the demand message or the master clock (bit-master) signal on the AccuLink / ComfortLink II bus. Shown as Err 91 on the AccuLink thermostat pro repair	Communicating-bus wiring fault – data (D) line broken, grounded, or D and B reversed at the outdoor unit; 0VDC measured on the data line indicating a broken or grounded data wire; Failed master control board on the bus	Power-cycle the system at the breakers, wait one minute, and allow a few minutes to re-establish communication
102	Y2 without Y1 – miswire, 24-volt (non-communicating) mode (CL2.102). A second-stage cooling call (Y2) is present without the first-stage call (Y1), indicating reversed or incorrect field control wiring pro repair	Y1 and Y2 field control wires reversed or miswired at the outdoor unit	This is a wiring / installation fault – no safe homeowner check beyond confirming the thermostat is set to Cool; contact a licensed technician
113	Liquid Pressure Sensor Fault – out of range, open or shorted (CL2.113). The liquid-line pressure transducer reading is invalid (0VDC = shorted, 4.99VDC = open). Shown as Err 113 on the AccuLink thermostat pro repair	Liquid-line pressure transducer open, shorted, or out of range; Transducer wiring or connector fault at the outdoor control board	Try one power cycle of the air conditioner at the breaker and allow several minutes
114	Personality Module (PM) Fault (CL2.114). The PM (configuration module on the outdoor control board) is missing, unseated, corrupted, or mismatched to the unit. Some sub-codes allow continued operation with a displayed fault; others stop the compressor until a good PM is present. Shown as Err 114 on the AccuLink thermostat pro repair	Personality Module missing, not seated, or corrupted on the outdoor control board; PM data corrupted by a power surge or faulty field wiring; Wrong or mismatched PM installed after a board service (capacity mismatch to indoor unit)	Try one power cycle at the breaker; if the code persists this requires service
126	Equipment Change Alert / thermostat communication fault (CL2.126). The AccuLink thermostat detects that the equipment reporting on the bus no longer matches what was discovered at startup, or it has lost communication with a piece of equipment. Shown as Err 126 / Error 126 on the AccuLink display pro repair	A communicating component went offline (open data line, ~16VDC on the bus instead of 12VDC); Loose, corroded, or reversed communicating-bus (data) wiring; A component lost power or was changed without being re-discovered	Check the thermostat is seated firmly on its base; Verify the outdoor unit breaker and disconnect are ON; Power-cycle the system at the breakers, wait about one minute, restore power, and allow a few minutes to re-establish communication
174	Suction Pressure Sensor Fault (variable-speed models, CL2.174). The suction pressure transducer is missing, open, shorted, or out of range (0VDC = shorted, 4.99VDC = open), which can also indicate a refrigerant-pressure or airflow problem pro repair	Suction pressure transducer open, shorted, missing, or out of range; Transducer wiring or connector fault at the outdoor control board; Underlying refrigerant-pressure or airflow problem	Replace a dirty air filter and confirm vents are open; Clear debris from around the outdoor unit, then try one power cycle at the breaker
184	Protection Algorithm Fault (variable-speed models, CL2.184). The drive has shut the compressor down to protect it – sub-codes include indoor coil freeze protection in cooling, compressor high-dome-temperature protection, low suction pressure protection, and a universal hard lockout after repeated protection shutdowns pro repair	Restricted airflow, low refrigerant charge, or low-ambient operation (indoor coil freeze, low suction pressure); High superheat at the compressor from low charge, a restricted metering device, or restricted condenser airflow in cooling; Repeated protection shutdowns leading to a hard lockout	Replace a dirty air filter and make sure supply and return vents are open; Clear leaves, grass, and debris from the outdoor condenser so air flows freely (do not open the unit); Try one power cycle at the breaker, then allow several minutes

American Standard air conditioner codes we get called for most

18 — 24V Sensing Error / Control Fault (AC Sns Err / CTRL FLT, CL2.018). 24V is not being sensed at the Y1 input (J1 connector) of the outdoor control board, or the outdoor control board has an internal failure. Shown as Err 18 on the AccuLink thermostat

Typical causes include missing or faulty y1 (red wire) 24vac signal reaching the outdoor control board; loose or corroded low-voltage wiring at the outdoor unit j1 connector; internal failure of the outdoor control / inverter board, sometimes caused by a line-voltage spike or static discharge. A few things are safe to check yourself (Confirm the thermostat is set to Cool with the setpoint below room temperature; Check that the outdoor disconnect and the breaker for the air conditioner are both ON), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 18 on American Standard air conditioners throughout Greater Vancouver.

67 — Temperature Sensor Fault – out of range, open or shorted (CL2.067). Covers the outdoor Ambient, Coil, Liquid, or External Outdoor Temperature sensor depending on sub-code. Shown as Err 67 on the AccuLink thermostat

Typical causes include outdoor ambient, coil, liquid, or outdoor-temperature sensor open, shorted, or out of range; damaged sensor wiring or a loose sensor connector on the outdoor control board; failed temperature sensor (thermistor). A few things are safe to check yourself (Try one power cycle of the air conditioner at the breaker and allow several minutes to clear), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 67 on American Standard air conditioners throughout Greater Vancouver.

89 — Equipment Missing / Configuration Fault (Config Fault, CL2.089). Equipment that was auto-discovered at startup is no longer reporting on the communication bus – the thermostat expected a component (such as the outdoor unit) and can no longer find it

Typical causes include loss of communication to the outdoor unit or another component (open or shorted data line; ~16vdc on the bus instead of a healthy 12vdc); a breaker tripped or power lost to one piece of equipment; loose communicating-bus connection at a component. A few things are safe to check yourself (Verify the breaker and disconnect for the outdoor unit are ON; Power-cycle the system at the breakers, wait one minute, and allow it to re-discover equipment), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 89 on American Standard air conditioners throughout Greater Vancouver.

79 — Low Pressure Cut-Out (LPCO) Fault (CL2.079). The low-pressure switch has opened. Sub-codes cover a short lockout, a heat/cool lockout, and a hard lockout after the third trip in the same call (cycle power to reset). In cooling, suction pressure has dropped below the low-pressure limit. Shown as Err 79 on the AccuLink thermostat

Typical causes include system low on refrigerant charge (leak); indoor airflow restriction in cooling (dirty filter, blocked return, dirty indoor coil); low-pressure switch wiring open or shorted. A few things are safe to check yourself (Replace or clean the indoor air filter if dirty; Make sure supply and return vents are open and unobstructed), but the repair is a licensed HVAC technician job. HeatLand diagnoses and fixes 79 on American Standard air conditioners throughout Greater Vancouver.

Is it safe to keep running a American Standard air conditioner with a fault code?

Most American Standard fault codes put the air conditioner into a safe lockout for a reason. You can safely check the basics — the power and breaker on, the air filter clean, the outdoor condenser clear of debris, and the thermostat set to cool — and restart it once. If the code returns, stop and book a technician. Air-conditioner faults are electrical and refrigerant issues — never open the unit or touch the wiring or refrigerant lines yourself.

American Standard air conditioner repair across Greater Vancouver

HeatLand has kept Metro Vancouver homes comfortable since 1999. Our licensed, insured technicians diagnose and repair American Standard air conditioners — sensor and thermistor errors, communication faults, fan and compressor problems, refrigerant and pressure faults, and control-board issues — including units we didn’t install. We’re brand-agnostic, carry common parts, and give you an honest repair-or-replace assessment with upfront pricing and a free estimate. If your air conditioner is beyond economical repair, we’ll show you right-sized, high-efficiency replacement options and the rebates available.

Need it sorted fast? We offer priority emergency air conditioner repair. Explore Air Conditioner services, browse all air conditioner error codes by brand, or request a free estimate.

American Standard air conditioner service areas

We repair American Standard air conditioners across Greater Vancouver and the Fraser Valley, including:

American Standard air conditioner error code FAQs

Can I reset my American Standard air conditioner myself?

Yes — power-cycling the unit at the breaker once is generally safe after you’ve checked the basics (the power and breaker on, the air filter clean, the outdoor condenser clear of debris, and the thermostat set to cool). If the air conditioner faults again right away, stop and note the code — repeatedly resetting a air conditioner that keeps locking out can mask a real problem. Call a licensed HVAC technician to diagnose it.

What does the American Standard 67 code mean?

On American Standard air conditioners, 67 commonly indicates temperature sensor fault – out of range, open or shorted (cl2.067). covers the outdoor ambient, coil, liquid, or external outdoor temperature sensor depending on sub-code. shown as err 67 on the acculink thermostat. Confirm the exact meaning against your unit’s manual — codes can vary by model and series — and have the repair done by a licensed HVAC technician. HeatLand fixes this across Greater Vancouver.

Do you repair American Standard air conditioners you didn’t install?

Yes. HeatLand is brand-agnostic and services American Standard air conditioners throughout Metro Vancouver and the Fraser Valley, whether or not we installed the unit. We carry common parts and give you an honest repair-or-replace assessment.

Is a American Standard air conditioner fault code an emergency?

No heat in cold weather or no cooling in a heat wave is worth treating urgently. For priority air conditioner repair across Greater Vancouver, call (604) 330-3812.

How much does American Standard air conditioner repair cost in Vancouver?

It depends on the fault. Many American Standard codes point to sensors, thermistors, capacitors or control parts — usually far cheaper than replacement. We give upfront pricing and a free estimate before any work.

More Air Conditioner error-code guides

HeatLand repairs every major air conditioner brand across Greater Vancouver. More brand guides: