The answer to 'heat exchanger not turning on' is that a malfunctioning heat exchanger is a common issue that can have several potential causes, including a faulty thermostat, a problem with the blower motor, or a buildup of dirt and debris. Symptoms may include the furnace not turning on, poor airflow, or strange noises coming from the unit.
In some cases, the issue can be resolved through basic troubleshooting and cleaning, but more serious problems may require the expertise of a professional HVAC technician. It's important to address a non-functioning heat exchanger promptly, as it can lead to safety concerns and further damage to the system if left unresolved.