HVAC in Maryland is a humidity job as much as a temperature job, except in the mountains where heat runs longer. Piedmont and Shore houses spend summer pulling water out of the air, not only heat out of the room. Western houses still need equipment that survives a hard freeze. Tell us whether the trouble is cooling, heat, or air that feels wet when the set point says it should not.
The house decides the equipment more than any trend does. Older city blocks may still run boilers and radiators, with a window unit fighting the top floor. Suburban houses usually have ducts, a heat pump or a furnace paired with an outdoor unit, and an attic that heats the supply air before it ever reaches a bedroom. Salt air near the bay is hard on metal that sits outside.
Say what the equipment is doing, not what you guess the part is called. No cool air, short cycling, ice on the line outside, a smell when the heat first starts, or rooms that never catch up are enough to begin. In a tall older house the top floor cooks while the basement stays clammy. That split is common from the older towns to the tight blocks, and it changes where the work starts. A thermostat in a hallway can lie about a bedroom that faces the afternoon sun.
Blocked returns, a collapsed duct, and a filter that has not been changed can mimic a dead compressor. If you already changed the filter, say so. If the outdoor unit sits in a shrub bed or a narrow side yard with no free air, say that too. Do not try to name the failed part. Describe the symptom, the floor that suffers, and whether anyone has already opened the cabinet.
Have the part of the state ready, and say whether the fuel is gas, oil, electric, or a heat pump. A checkup before the hot season and a no-heat night are different calls, and both belong here. HVAC in Maryland has to handle sticky summers and real winters, sometimes in the same year, and the mountains do not get the same balance as the Shore. Call the number on this page.