HVAC Error Code F7 — What It Means & How to Fix It

What Does This Error Mean?

F7 means the outdoor discharge temperature sensor has a fault. The discharge sensor monitors the temperature of refrigerant leaving the compressor. This is one of the hottest points in the system — the compressor protects itself by watching this reading closely. If the sensor fails, the system loses this protection and may shut down to avoid damage. F7 can also appear when the discharge temperature is genuinely too high.

Affected Models

Mini-split heat pumps
Inverter split systems
Central air conditioners
Variable-speed heat pump systems

Common Causes

The discharge sensor probe has failed from prolonged heat exposure near the compressor
Sensor wiring has been damaged or has corroded due to moisture getting into the outdoor unit
Low refrigerant charge is causing the compressor discharge temperature to spike into the fault range
Refrigerant overcharge is creating high discharge temperatures and triggering the sensor threshold
The outdoor control board has failed and is misinterpreting the sensor signal

How to Fix It

Turn off the system immediately at the thermostat and at the outdoor disconnect box. High compressor discharge temperatures can damage the compressor quickly.

Do not try to restart the system repeatedly if F7 keeps appearing. Each restart cycle puts more stress on the compressor if the root cause is not just a sensor failure.
Check that the outdoor unit has clear airflow on all sides. Shrubs, fences, or debris closer than 18 inches can restrict airflow and cause discharge temperatures to rise.

Remove any leaves, grass clippings, or debris from the sides and top of the unit. Restricted airflow is a common and easily fixed cause of discharge temperature faults.
Check that the outdoor unit's condenser coil fins are not severely dirty or bent. Clogged fins prevent heat from escaping and drive discharge temperatures up.

You can gently spray the coil fins with a garden hose from inside the unit outward to clean them. Do this only with power off at the disconnect.
Restore power and restart the system. Watch for F7 to return. If the system runs without error for several hours, the issue may have been a one-time high-temperature event.

If the outdoor ambient temperature was extremely high when F7 appeared, that may have been a contributing factor. Monitor during the next hot day.
If F7 returns, call an HVAC technician. They will test the sensor and measure refrigerant pressures to determine whether the sensor or the refrigerant charge is the actual cause.

A technician with manifold gauges can diagnose refrigerant issues in minutes. Do not delay — a compressor damaged by overheating is a $1,000 to $3,000 replacement.

When to Call a Professional

F7 requires professional diagnosis — especially if refrigerant levels are involved. Only EPA-certified technicians are legally permitted to handle refrigerant. If the sensor itself is the issue, replacement costs $100 to $250. If refrigerant is the cause, expect additional costs for leak detection and recharge. Call an HVAC technician promptly — running the compressor at high discharge temps risks serious damage.

Frequently Asked Questions

Is F7 the same as the compressor overheating?

Not necessarily — F7 specifically means the discharge sensor has reported a fault. This could be a true high-temperature condition or simply a failed sensor sending a bad reading. A technician uses refrigerant pressure gauges and a digital thermometer to tell the difference. If refrigerant pressures are normal and the temperatures are normal, the sensor is likely bad.

Can low refrigerant cause an F7 error?

Yes — low refrigerant is a common cause of genuinely high discharge temperatures. When refrigerant is low, the compressor has to work harder and runs hotter than normal. If your system has also been cooling or heating poorly recently, low refrigerant is a likely suspect. A refrigerant leak check and recharge will be part of the diagnosis.

How hot does HVAC discharge gas normally get?

Normal compressor discharge temperatures typically range from 150°F to 225°F depending on conditions. An F7 fault usually triggers when the sensor reads above 230°F to 260°F — exact thresholds vary by brand. At these temperatures, compressor oil breaks down and bearing surfaces can be damaged. The sensor protection system exists specifically to prevent catastrophic compressor failure.