The answer to 'emergency HVAC service not working' is that there can be several common causes, including a failed thermostat, issues with the electrical system, refrigerant leaks, or a malfunctioning compressor. Symptoms may include the system not turning on at all, short-cycling, or blowing warm air. In some cases, the issue may be a simple fix like a tripped circuit breaker or clogged air filter, but more complex problems will require professional HVAC repair.
If your HVAC system is not working, the first step is to check for any obvious issues you can address yourself, like changing the air filter or resetting the thermostat. However, if the problem persists or you're unsure of the cause, it's best to call an experienced HVAC technician to diagnose and repair the issue. Attempting complex repairs without the proper training and equipment can be dangerous and may end up costing more in the long run.