Trane HVAC Error Code 35: How to Fix It

Q: What does error code 35 mean on a Trane HVAC system?

Error code 35 on a Trane HVAC system indicates a heat strip fault. This means the control board has detected a problem with one or more of the electric resistance heating elements — such as an element that has burned out, a high-limit safety switch that has tripped due to overheating, or a failed heat sequencer that is preventing the strips from activating properly.

Q: Can I reset Trane error code 35 myself?

Yes, in many cases you can reset the error by first turning off power at the breaker, pressing the reset button on the high-limit safety switch inside the air handler, replacing a clogged air filter, and restoring power. However, if the fault returns after resetting, there is an underlying problem such as a failed heating element or sequencer that needs to be diagnosed and repaired before the error will clear permanently.

Q: How much does it cost to repair a Trane heat strip fault?

The cost depends on what has failed. Replacing an air filter costs just a few dollars. A replacement high-limit safety switch typically costs $10 to $30 for the part. A heat strip element replacement can range from $50 to $150 for parts, plus $100 to $200 in labor if a technician is called. A heat sequencer replacement is usually $20 to $60 for the part. Total professional repair costs typically range from $150 to $400 depending on what needs to be replaced and local labor rates.

Q: Why does my Trane heat strip keep tripping the high-limit switch?

The most common reason a Trane heat strip repeatedly trips the high-limit safety switch is restricted airflow. This is usually caused by a dirty or clogged air filter, blocked supply or return vents, a slow or failing blower motor, or ductwork obstructions. The heat builds up with nowhere to go, causing the element to overheat and the safety switch to trip. Always check and replace your air filter first, and make sure all vents in your home are open and unobstructed.

Q: Is it safe to run my Trane HVAC system with error code 35 active?

It depends on your system configuration. If error code 35 is active, the heat strips are not functioning, so your system will not provide electric heat. If you have a heat pump, the compressor may still provide some heating capacity. Running the system without resolving the error is generally not dangerous in the short term, but you should not attempt to bypass or disable the high-limit safety switch, as it is a critical component that prevents fires and overheating damage to your equipment.

Abstract

Trane HVAC error code 35 indicates a heat strip fault, meaning one or more of the electric resistance heating elements in your air handler or heat pump system has failed, overheated, or lost electrical continuity. This error commonly appears when a high-limit safety switch trips, a heating element burns out, or there is a wiring issue affecting the heat strips. While this is a medium-severity issue that won't immediately damage your system, it does mean your home may not heat properly until the fault is resolved.