What Parts to Replace When the Heater Isn't Hot?

[SanColeman]

When the heater isn't hot, you may need to replace the thermostat. The reasons for the heater not being hot include: insufficient coolant, damaged thermostat, clogged heat exchanger, circuit failure in the heating system, etc. The details are as follows: Insufficient Coolant: Due to damaged components in the engine's water circulation system, leaks at interfaces, or blown cylinder gaskets, the coolant may be insufficient. This results in only a small amount or no coolant circulating in the heater pipes, causing the heater to not produce heat. The solution is to ensure the engine's water circulation system is functioning properly and then replenish the coolant. If there are other issues, repair them first and then add coolant to the normal level. Thermostat Malfunction: If the thermostat was damaged during previous repairs due to issues like high water temperature, it might remain stuck in the open position. This causes the engine's water circulation to stay in a large loop continuously. Combined with low external temperatures and efficient heat dissipation, the engine's water temperature struggles to rise, leading to a lack of heat from the heater. The solution is to install or replace a new thermostat.