HVAC Error Code E13 — What It Means & How to Fix It

What Does This Error Mean?

E13 on an HVAC system typically indicates a refrigerant pressure fault. The system detected that refrigerant pressure is abnormally high or low. This can mean a refrigerant leak, a blocked coil, or a failed pressure sensor. When pressure is outside safe limits, the HVAC system shuts down to prevent compressor damage. Do not attempt to run the system continuously with E13 — you risk destroying the compressor, which is one of the most expensive components to replace.

Affected Models

Carrier, Trane, Lennox, and Goodman split systems
Daikin, Mitsubishi, and LG mini-splits
Rheem and Ruud heat pumps
Most residential and light commercial HVAC systems

Common Causes

Low refrigerant level due to a leak in the refrigerant circuit
High refrigerant pressure caused by a blocked or dirty condenser coil (outdoor unit)
A failed high-pressure or low-pressure safety switch that triggered incorrectly
The outdoor unit fan motor has failed, causing heat to build up and pressure to rise
A restriction in the refrigerant line — often from a kinked copper line or a clogged filter drier

How to Fix It

Turn off the HVAC system immediately. Do not keep trying to run it. Set the thermostat to Off. A system with a refrigerant pressure problem will attempt to run, fail, and try again — each attempt stresses the compressor.

The compressor is the most expensive component in an HVAC system — often $1,000–$2,500 to replace. Protecting it by shutting down promptly is the most important step.
Check the outdoor unit (condenser). Make sure nothing is blocking airflow — leaves, dirt, grass clippings, or debris on or around the unit restrict airflow and cause high-pressure faults. Clear any visible debris from around the unit.

The outdoor unit needs at least 18–24 inches of clearance on all sides for proper airflow. Overgrown shrubs, fencing, or stored items too close to the unit are a common cause of high-pressure errors.
Check the air filter inside your home. A heavily clogged filter reduces airflow through the indoor coil, which can cause pressure imbalances in the refrigerant circuit. Replace the filter if it is visibly dirty or has not been changed in over 3 months.

A standard 1-inch filter should be replaced every 1–3 months. A thick 4-inch media filter lasts 6–12 months. Using the wrong filter size or a filter that is too restrictive can also cause airflow problems.
Listen to the outdoor unit when the system is briefly turned on. The condenser fan (on top of the unit) should be running. If the fan is not spinning or is spinning slowly, a failed fan motor is causing the high pressure that triggered E13.

A failed outdoor fan motor is one of the most common causes of high-pressure faults in summer. The fan keeps the condenser coil cool — without it, refrigerant pressure spikes rapidly.
Call a licensed HVAC technician. Provide them with the error code (E13) and any observations you made — whether the outdoor fan was running, whether there are visible ice on the lines, or any unusual sounds.

An HVAC technician will connect refrigerant gauges to measure actual system pressure, check for leaks with a leak detector, and diagnose whether the pressure switch, refrigerant level, or another component is the root cause.

When to Call a Professional

E13 almost always requires a licensed HVAC technician. Refrigerant handling requires EPA 608 certification — homeowners cannot legally purchase or add refrigerant. Diagnostic visit costs $80–$150. Refrigerant leak repair and recharge: $200–$1,500 depending on the refrigerant type and severity of the leak. Compressor replacement (if damaged): $1,200–$2,500. Do not delay — running a low-refrigerant system destroys the compressor.

Frequently Asked Questions

Can I add refrigerant to my HVAC system myself?

No — it is illegal in the United States for unlicensed individuals to purchase or handle HVAC refrigerants. The EPA requires technicians to have Section 608 certification to work with refrigerants. Do-it-yourself refrigerant products sold online are not the same as the refrigerants used in central HVAC systems. Always call a licensed HVAC technician for refrigerant issues.

How do I know if my HVAC system has a refrigerant leak?

Signs of a refrigerant leak include: the system runs continuously but the house does not reach the set temperature, ice forming on the copper refrigerant lines or indoor coil, a hissing or bubbling sound near the outdoor unit, and higher-than-normal electricity bills. A licensed technician can confirm a leak with an electronic leak detector or ultraviolet dye.

How much does it cost to fix E13 on an HVAC system?

It depends on the cause. A dirty condenser coil cleaned by a technician: $100–$200. A failed pressure switch: $100–$250 parts and labor. Refrigerant leak repair and recharge: $300–$1,500 depending on the refrigerant type (R-22 is very expensive due to phase-out). If the compressor was damaged from running with low refrigerant: $1,200–$2,500 or more. Early diagnosis prevents the most expensive outcomes.