One of the most common HVAC issues is a lack of warm or cool air coming from the vents. If a heater or air conditioner fails to do its job, you may start wondering if the time has come for HVAC replacement, but this problem could be caused by clogged air filters. Damaged ductwork may also be to blame. A malfunctioning blower motor could be the culprit as well. With AC units, low coolant levels may cause the system to blow out warm air instead of cool. Listed above are a few solutions to the problem which can be easily resolved on your own, although, you may benefit better a replacement service.