What Causes One Side of the Car Radiator to Be Hot and the Other Side Cold?
2 Answers
Here are the reasons why one side of the car's heating system is hot and the other side is cold: Specific reasons: Damaged air filter; insufficient refrigerant; blockage in the heater core channel leading to inadequate hot water flow; the air duct on the cold side may not be open or is blocked. It is necessary to check whether the control flap cable for the heater core's hot and cold air is detached, whether the heater fan is damaged, or whether the flap has fallen off. Heating system: The heating system simply utilizes the car's internal heat circulation process and does not require the activation of the car's compressor. The heating is generated by the heat dissipated after the engine is running. A small fan in the engine compartment blows the heat collected from the engine cooling system into the car's interior.
The radiator is half hot and half cold, I've seen this many times, most commonly due to uneven cooling system causing localized temperature differences. It could be because the water pump isn't working well and coolant can't circulate; or there's scale or rust buildup inside the radiator blocking half the water flow; or there might be air bubbles in the system preventing heat from spreading. If the water pump is inefficient and can't push water properly, one side stays cold; blockages or air bubbles will create even more unevenness. Don't underestimate this issue—if the engine heats unevenly, it might overheat and blow the head gasket, leading to costly repairs. I suggest keeping an eye on the dashboard temperature gauge while driving. If you notice this phenomenon, shut off the engine immediately to reduce risks. It's best to take it to a professional repair shop to check the water pump, flush the radiator, or bleed the air from the system. Early intervention saves big money—this is a lesson I've learned from years of experience.
