What Causes the Car Heater to Not Get Hot?
2 Answers
Car heater not getting hot is caused by a clogged cabin air filter or a faulty thermostat. The details are as follows: Clogged Cabin Air Filter: The cabin air filter is related to the air intake of the air conditioning system. Once the cabin air filter is clogged, the air intake of the entire air conditioning system becomes restricted. Dust or dirt blocking the filter leads to clogging, thereby affecting the heating performance of the heater. The solution is to clean the cabin air filter. Faulty Thermostat: A faulty thermostat prevents effective temperature control, causing the cooling system to enter the large circulation prematurely, which results in the heater not getting hot. The solution is to repair or replace the thermostat.
I often drive for travel and have encountered the issue of the heater not blowing warm air several times. Last month, during a snowy trip, I noticed the car was blowing only cold air. After checking, it turned out the coolant level was too low—topping it up to the midpoint between the markers solved the problem. Another time, the engine's thermostat was stuck closed, preventing the engine from reaching optimal temperature, which naturally resulted in insufficient heat from the heater. Additionally, if there are air bubbles trapped in the cooling system blocking the heater core's pipes, heat can't be transferred effectively, leaving you shivering. During winter, regularly inspecting the coolant reservoir's color and level is crucial. If you spot any leaks or deterioration, replace it promptly. If the heater remains cold after the car has been parked for a while, it's advisable to visit a professional shop for a system bleed test to ensure there are no blockages. Addressing such minor issues early is key to avoiding discomfort during long drives.