B. If both hoses to the heater core are hot, coolant is circulating through the heater core. One hose that is significantly cooler than the other would indicate a clogged heater core. However, if the temp control cable is incorrectly adjusted, the temp blend door may not allow enough warm air to enter the passenger cabin for sufficient heating.

Customer complains of poor heat output. After checking hoses from heater core and finding them both to be hot Tech A says it could be a clogged heater core. Tech B says a misadjusted temp control cable would be the problem. Who is right?

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