The answer to 'emergency HVAC service not cooling' is that there could be several common causes, including a refrigerant leak, a problem with the compressor, or a clogged air filter. Symptoms may include warm air blowing from the vents, the system running constantly without cooling, or the compressor not turning on at all.
If you're experiencing an emergency HVAC issue where your system is not cooling, the first step is to check the air filter and replace it if it's dirty. You can also try resetting the circuit breaker. However, if those basic troubleshooting steps don't resolve the issue, it's best to call a professional HVAC technician to diagnose and repair the problem. Attempting complex repairs on your own could be unsafe and may even void your warranty.