The answer to 'HVAC repair blowing cold air' is that there could be several common causes, including a refrigerant leak, a problem with the compressor or fan, or an issue with the thermostat or control system. Symptoms may include the air coming out of the vents feeling significantly colder than normal, the system running constantly without reaching the set temperature, or the compressor not turning on at all.
In some cases, the issue can be a simple fix like replacing a faulty thermostat or cleaning the condenser coils. However, more complex problems like a refrigerant leak or compressor failure will likely require professional HVAC repair. It's generally best to call in an experienced HVAC technician to diagnose and repair the issue, as improper DIY attempts could lead to further damage or safety concerns.