York Heat Pump Error Codes and Troubleshooting Guide

York Heat Pump Error Codes help homeowners and technicians quickly identify operational faults, safety trips, and diagnostic states. This guide explains common codes, likely causes, diagnostic steps, and recommended actions to restore reliable operation. It focuses on York-branded residential heat pumps used across the U.S., including common models and control systems.

Code	Meaning	Typical Action
Lockout / E1	Compressor Overcurrent or System Lockout	Reset, Check Compressor & Capacitor
Low-Pressure / LOP	Low Refrigerant Pressure	Check Refrigerant Charge, Leak Test
High-Pressure / HOP	High Discharge Pressure	Check Condenser Airflow, Clean Coil
Outdoor Sensor / OD	Outdoor Temp Sensor Fault	Inspect Wiring, Replace Sensor
Defrost / dF	Defrost Cycle Active Or Fault	Verify Defrost Components

How York Heat Pump Error Codes Are Organized

York error codes are presented by the outdoor unit controller or the indoor control board and can appear as alphanumeric displays, LED flash patterns, or fault message strings on thermostats. Understanding the display format is the first step: consult the unit’s nameplate and owner manual for model-specific code tables.

Codes typically fall into categories: safety trips (over/under pressure or temperature), sensor failures, communication faults, electrical supply issues, and refrigerant system anomalies. Each category affects operation differently and requires targeted diagnostics.

Common York Error Codes And Meanings

This section lists frequently encountered York Heat Pump Error Codes and a concise interpretation. Specific code labels vary by model; the descriptions below cover the underlying fault so the reader can match similar messages.

Lockout / Compressor Fault

Lockout often appears after repeated short cycling or a detected overcurrent condition. The controller will prevent compressor restart until the cause is resolved and the lockout is cleared. Typical indicators include an E1, LCK, or LED flash pattern referencing compressor protection.

Low Pressure / LOP

Low-pressure faults indicate the refrigerant circuit pressure has dropped below safe operating thresholds. Causes include refrigerant leaks, metering device malfunctions, or restricted liquid lines. Operation stops to protect the compressor from damage due to suction starvation.

High Pressure / HOP

High-pressure faults occur when discharge pressure exceeds safe limits. Common triggers include dirty condenser coils, blocked airflow, non-condensables in the refrigerant, or a faulty pressure sensor. The unit may lock out or cycle the compressor to reduce pressure.

Outdoor Sensor Fault

Outdoor sensor faults are signaled when the outdoor temperature sensor is open, shorted, or out of range. The controller may default to conservative operation or fault out the heat pump if outdoor sensing is critical for defrost or head pressure control.

Defrost Related Codes

Defrost messages indicate active defrost cycles or problems with the defrost thermostat or control. Long or repeated defrost cycles can point to incorrect refrigerant charge, failing reversing valve, or failed outdoor fan motor affecting heat exchange.

Communication Faults

Communication errors between indoor and outdoor boards or between thermostat and control often show as com, Err, or flashing LEDs. Causes include broken wiring, loose connectors, or failed control modules. These errors prevent coordinated operation and often inhibit heating function.

Step-By-Step Troubleshooting Workflow

This workflow provides a logical progression to diagnose and resolve most York Heat Pump Error Codes. Technicians should follow safety protocols and use proper tools when working with electrical and refrigerant systems.

1. Record The Code And Operating Conditions: Capture the exact display, ambient temperatures, and recent events before powering down the unit.
2. Perform A Visual Inspection: Look for obvious issues—tripped breakers, burned connectors, ice on coils, oil stains at fittings, or rodent damage to wiring.
3. Check Power And Grounding: Verify correct line voltage at the unit, proper phase if three-phase, tight lugs, and good grounding. Voltage imbalances cause compressor faults.
4. Confirm Airflow And Filters: Restricted airflow raises internal pressures. Clean filters, ensure supply and return vents are open, and inspect the outdoor coil for debris.
5. Measure Pressures And Temperatures: Use manifold gauges and thermometers to confirm suction/discharge pressures and superheat/subcooling values for refrigerant diagnosis.
6. Test Sensors And Controls: Check sensor resistances against manufacturer tables. Inspect communication wiring and connectors for continuity.
7. Address Refrigerant Issues: If low charge or leak suspected, perform a leak test and repair before recharging to the specified charge.
8. Clear Faults And Monitor: After repairs, clear stored faults per the service manual and observe several cycles to ensure stable operation.

Tools And Measurements Recommended

Accurate diagnostics require basic HVAC and electrical tools. The following list highlights the essentials.

• Multimeter (voltage, current clamp, resistance)
• Refrigerant manifold gauges and hoses
• Thermometer or infrared temperature gun
• Leak detector (electronic or UV dye kit)
• Insulated hand tools and nut drivers
• Portable vacuum pump and recovery machine (EPA compliance)

Model-Specific Notes And Control Variations

York heat pumps span multiple product lines and control platforms such as the Affinity, LX, and legacy residential units. Error code labels and clearing procedures vary by controller firmware. Always reference the model-specific service manual for exact code tables, wiring diagrams, and recommended spare parts.

Some models log historical faults that can be downloaded or viewed via a service connector, offering context for intermittent issues. Modern units may support remote diagnostics through building automation interfaces.

DIY vs Professional Service: When To Call A Technician

York Heat Pump Error Codes related to simple issues—tripped breakers, clogged filters, thermostat misconfiguration, or sensor wiring that is easily accessible—can be handled by competent homeowners. However, refrigerant handling, compressor replacement, control board swaps, and high-voltage work require a licensed HVAC technician.

Call a professional if the fault involves refrigerant leaks, compressor lockouts, repeated high- or low-pressure trips, or any time safety devices or PCB diagnostics indicate component failures. Improper intervention can void warranties and create hazards.

Preventive Maintenance To Reduce Error Codes

Regular preventive maintenance reduces the frequency of faults and extends equipment life. A practical maintenance checklist includes annual or biannual inspections and seasonal tasks.

• Change or clean indoor filters every 1–3 months during heavy use.
• Inspect outdoor coil and fan monthly for debris and clear 2 feet around the unit.
• Check electrical connections and contactors for corrosion or pitting annually.
• Verify refrigerant charge and measure superheat/subcooling during yearly service.
• Test and replace failing sensors, capacitors, and motors proactively.

Safety And Warranty Considerations

York systems are covered by varying warranties that often require professional service records for claims. Homeowners should keep service logs and copies of invoices for warranty verification.

Working on refrigerant circuits requires EPA certification in the U.S. and adherence to environmental rules for recovery and disposal. Disconnect power before opening panels and follow lockout/tagout procedures to avoid injury.

Example Troubleshooting Scenarios

Scenario: Outdoor Unit Displays Low Pressure (LOP)

Symptoms: Heat pump stops on low-pressure fault after several short cycles. Gauges show low suction pressure and the outdoor coil is cold and frosted.

Likely Causes: Refrigerant leak, partially blocked metering device, or malfunctioning TXV/orifice.

Recommended Steps: Inspect for oil at fittings, perform electronic leak detection, repair leak, evacuate, and recharge to manufacturer charge. Confirm proper superheat after repair.

Scenario: Compressor Lockout After Power Event

Symptoms: Unit failed to restart after a utility outage and shows a lockout or compressor protection error.

Likely Causes: Motor overload caused by brief voltage dip or stuck relay; failed start capacitor or contactor welding.

Recommended Steps: Check incoming voltage and continuity to the compressor, test start/run capacitors, inspect contactor contacts, and clear lockout following the service manual. Replace failed components.

Reference Resources And Where To Find Model Codes

Useful resources include the York installation and service manuals, OEM technical bulletins, and authorized distributor portals. Manufacturers often publish downloadable code tables and wiring diagrams for specific model numbers.

For warranty or parts, contact York’s authorized service network or visit the Johnson Controls / York professional support pages. Keep the unit model and serial number available when requesting support.

Quick Troubleshooting Checklist For Common Codes

Code Type	Quick Checks	Immediate Action
Lockout / Compressor	Breaker, voltage, capacitor, contactor	Reset after fixing electrical issue
Low Pressure	Gauge pressures, check for oil stains	Leak test, repair, recharge
High Pressure	Outdoor coil cleanliness, fan operation	Clean coil, repair fan, check refrigerant
Sensor Fault	Wire continuity, resistance vs spec	Replace sensor or repair wiring
Comm Fault	Thermostat wiring, module connectors	Secure connections, replace faulty board

Readers should treat the error code descriptions here as a practical guide. Model-specific values and procedures are available in York service manuals. When in doubt, a qualified York technician will diagnose complex faults safely and preserve warranty coverage.