What should the temp of the air be coming out of the vents when the furnace is on?

When the furnace is operating properly, the air coming out of the vents should typically be between 120°F to 160°F (49°C to 71°C). However, this can vary based on the type of heating system and the specific settings. If the air temperature falls significantly outside this range, it may indicate an issue with the furnace or the heating system. Regular maintenance can help ensure optimal performance and temperature output.