A customer reports inconsistent heater operation. Technician A believes the water pump is faulty, while Technician B suspects low coolant levels. Who is correct?

Inconsistent heater operation can often be linked to the level of coolant in the system. When the coolant level is low, it can create air pockets within the cooling system, leading to inadequate circulation of heated coolant through the heater core. This disruption can result in fluctuating temperatures from the heater, causing the inconsistency that the customer is experiencing.

While a faulty water pump could theoretically contribute to heating issues by not circulating coolant effectively, it is less likely to be the root cause in this scenario when the primary issue reported is inconsistency, which points more directly to the potential for low coolant levels. If the coolant volume is sufficient, the water pump can typically move it around the engine and through the heater core efficiently, resulting in stable heater performance.

Moreover, low coolant levels are a common issue that can arise from leaks or evaporation, making it a more straightforward first diagnosis before exploring more complex reasons like pump failure. Therefore, suspicion of low coolant levels aligns more accurately with the symptoms of inconsistent heater operation.