Troubleshooting a Cold Car Heater

If your car’s heater is not producing sufficient heat, even when set to the “heat” position, a common cause is a clogged heater core. This guide outlines a method to clean the heater system.

Cleaning Procedure

1. Prepare Cleaning Agent: Crush 3 to 4 dishwasher detergent tablets into a powder using a knife.
2. Add to Cooling System: Introduce the powder into the car’s cooling system. This is typically done by accessing a hose connected to the system.
3. Refill and Drive: Refill the cooling system with the appropriate coolant mixture. Drive the vehicle for approximately five days.
   • Recommendation: Prioritize highway driving or driving at higher RPMs. This increased circulation helps pump more coolant, including through the heater core.

Explanation of Process

This method aims to dissolve the “brown sludge,” which is identified as oxide deposits that obstruct the heater core.

Post-Cleaning Steps

1. Drain System: After the five-day period, drain the entire cooling system.
2. Flush System: Thoroughly flush the entire system. Using a garden hose to flush the system is recommended.
3. Target Heater Core: It is advisable to flush the heater core directly during this step.

Alternative Professional Method

Workshops may employ a different method involving bypassing the heater core and filling it with a 25% acetic acid solution (vinegar). The system is then left to sit for a day before being flushed.