When diagnosing poor A/C performance, if only hot air is blowing out of the A/C outlets after moving the temperature control knob, who is correct?

When only hot air is blowing from the A/C outlets after adjusting the temperature control knob, it indicates that there may be a failure in the air conditioning system's cooling function. Option A likely refers to a scenario where an individual suggests the air conditioning system is not functioning properly, which is indeed correct.

The system's inability to produce cold air can stem from multiple issues, such as a malfunctioning compressor, inadequate refrigerant levels, or a problem with the evaporator coil. All these conditions can prevent the proper cooling air from reaching the cabin, leading to the experience of hot air blowing out instead.

Additionally, understanding how the temperature control knob works in relation to the A/C system is crucial. This knob typically adjusts a blend door that mixes outside and conditioned air to achieve your desired temperature setting. If this door is stuck in a position that allows only hot air to flow, that will also result in the issue described.

In contrast, the other options suggest that either the view put forth is inaccurate or that there are interpretations in which both A and B could be valid, which might not apply to this situation based on the information presented. Proper diagnosis requires a clear understanding of how these systems operate and the signal that a simple temperature adjustment should produce.