Hey, Why is My Car's Heater Not Working?

The proof image shows the melted blower motor electrical connector, which is the cause of the intermittent blower motor functioning.

A customer brought their vehicle to the shop because its heater wasn't working properly. Sometimes, it worked fine in all settings, but in others, only at high-speed settings. They noticed that if they set the blower at high speed, it would work, and then they could adjust it to slower speeds. However, it never seemed to work if they tried starting it at a low-speed setting.

During the test drive, the technician observed that the blower motor worked inconsistently. While doing a vehicle health inspection, the technician found nothing relevant.

After the customer approved additional diagnostics, the technician accessed the blower motor and blower motor resistor under the dashboard. When attempting to back probe the electrical connector to the blower motor, they discovered the connector was melted. 

Nevertheless, the technician tested the voltage to the blower motor by back-probing the connector anyway; they found that the voltage was present at all speeds. This evidence indicated that the blower motor and its pigtail were melted causing the heater to work only sometimes at specific wiring angles, and would need to be replaced.

The proof image shows the broken blend door with its actuator removed, revealing the issue causing the lukewarm air problem in the vehicle's ventilation system.

A customer brought their vehicle to the shop because the air from the heater or AC vents was always lukewarm. It didn't get as hot or cold as it should.

During the test drive, the technician confirmed that the air temperature from the AC vent and heater fan remained lukewarm, regardless of the temperature settings on the panel. While doing a vehicle health inspection, the technician found no relevant issues.

After the customer authorized additional diagnostics, the technician used a specialized scanner designed for this vehicle to monitor the blend door's operation. They discovered that the blend door motor constantly turned when switching from hot to cold without making any clicking sound whatsoever.

The technician accessed the blend door motor and removed it from the airbox to investigate further. By adjusting the temperature settings, they observed the motor turning. Upon returning the blend door inside the airbox and observing it, they found that a crucial part of the door was broken, preventing the motor from properly managing the doors. 

To resolve this issue, the dashboard and airbox must be removed to replace the broken blend door entirely.

The proof image shows the removed thermostat, and you can see that it's stuck open, which prevents the vehicle from warming up as it should and triggers the check engine light to turn on.

A customer brought their vehicle to the shop, and they mentioned two concerns. Firstly, the check engine light was on, and secondly, they noticed the heater wasn't warm. They used to feel a lot of warmth from the heater while driving on the freeway, but now it takes a very long time to warm up.

During the test drive, the technician confirmed that the check engine light was indeed on, but they didn't notice any other concerns related to the customer. After a vehicle health inspection, the technician found no relevant issues. 

To investigate the check engine light, the technician did a vehicle code scan and P0116 code, which meant a problem with the engine coolant temperature. This was the lead to investigate the car heater problems.

With the customer's approval for additional diagnostics, the technician used a specialized scanner designed for this vehicle to verify the codes. They checked the live data of the vehicle and noticed that the engine temperature was not reaching the required level of 175° Fahrenheit.

To follow up on this, the technician used an infrared thermometer and found that the coolant temperature at the thermostat housing was reaching a maximum of 175°F.

Based on their findings, the technician recommended replacing the thermostat. After removing the thermostat, the technician found it in a stuck open position, even when it was cold. This confirmed that the faulty thermostat was the cause of the check engine light issue and why the heater wasn't warming up properly.

This proof image confirms the restricted flow in the heater core, which is causing the heating problem in the vehicle.

When the customer brought in their vehicle, they mentioned that the heater only worked while driving at freeway speeds. The heater's temperature wouldn't act right if they drove at normal speeds.

The technician confirms during a test drive that the car heater isn't working. So, it wasn't working as expected.

To diagnose the issue further, the technician conducted a vehicle health inspection. During this inspection, they didn't find any immediate problems related to the customer's concern.

However, to investigate the heating problem, the customer authorized additional diagnostics. Then, the technician used an infrared digital thermometer to read the temperature of specific car parts. They started the engine and measured the temperature at the upper radiator hose, which was 198ºF. 

Then, they checked the temperature of the heater hose going into the heater, which was 199ºF. However, the temperature coming out of the heater core was only 85°F. This temperature difference means the heater core was restricted, reducing coolant flow.

Based on the findings, the technician suggests trying a process called back-flushing the heater core to see if it helps restore proper coolant flow. They recommend replacing the clogged heater core if this attempt doesn't work.

Note that this sort of issue does not only affect small vehicles but can also be a pain for trucks. So, ensure you have a specialized mechanic with truck repair certification in similar cases.

The proof image shows the failed heater hose control valve, which remains closed even when it is supposed to open with electrical power. This causes the heater to run with low coolant, affecting the engine's cooling system, and is the reason why the heater is not functioning properly.

A customer brought their vehicle to the shop because the heater was not blowing any warm air, and the air conditioner felt like it was always running.

During the test drive, the technician confirmed that the heater was not blowing warm air. As part of the vehicle health inspection, the technician couldn't find any relevant issues. Therefore, the customer approved additional diagnostics.

The technician used an infrared temperature tool to check the engine's operating temperature, which was normal. They also checked the temperature before and after the heater control valve. Before the valve, the temperature was like the engine temperature, but after the valve, it was like the outside air temperature.

After back-probing the heater control valve's electrical connector, they found that the valve solenoid was receiving power and ground, but the valve itself was not opening. So, power was reaching it, but something internally was preventing the valve from working. As a result, the technician concluded that the heater control valve had internal damages and needed to be replaced.