8 Reasons Why Your Car Temperature Gauge Stays on Cold and AC is Not Working: Troubleshooting and Fixes.

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Have you ever experienced a situation where the temperature gauge in your car stays on cold, but the AC is not working? It can be quite frustrating, especially during hot summer months. There could be a variety of reasons for this issue, ranging from a simple malfunctioning sensor to a more complex problem with the engine control unit (ECU) or cooling system. In this blog post, we will discuss the 8 most common reasons for this issue and their fixes.

Causes

Malfunctioning Temperature Sensor

One of the most common reasons for a car’s temperature gauge to stay on cold is a malfunctioning temperature sensor. The sensor is responsible for measuring the temperature of the engine coolant and sending the signal to the gauge. If the sensor is faulty or damaged, it may send incorrect signals, resulting in a reading that shows the temperature as cold. To fix this issue, the sensor will need to be replaced.

Low Coolant Level

If the coolant level in your car is too low, it can also cause the temperature gauge to stay on cold. The coolant is responsible for absorbing heat from the engine and dissipating it through the radiator. If there is not enough coolant, the engine may not reach the proper temperature, resulting in a reading that shows the temperature as cold. To fix this issue, check the coolant level and add more if necessary.

Broken Thermostat

A broken thermostat can also cause the temperature gauge to stay on cold. The thermostat regulates the flow of coolant through the engine, and if it is stuck open, the coolant may not get hot enough to warm the engine. This can result in a reading that shows the temperature as cold. To fix this issue, the thermostat will need to be replaced.

Faulty Heater Core

If the heater core is faulty or clogged, it can also cause the temperature gauge to stay on cold. The heater core is responsible for heating the air that comes through the vents in your car, and if it is not working correctly, the AC may also be affected. To fix this issue, the heater core will need to be repaired or replaced.

Blown Fuse

A blown fuse can also cause the temperature gauge to stay on cold. The fuse is responsible for powering the sensors that send signals to the gauge, and if it is blown, the signals may not be able to reach the gauge, resulting in a reading that shows the temperature as cold. To fix this issue, replace the blown fuse.

Faulty Engine Control Unit

If the engine control unit (ECU) is faulty or damaged, it can also cause the temperature gauge to stay on cold. The ECU is responsible for regulating the temperature of the engine, and if it is not working correctly, it may send incorrect signals to the gauge. To fix this issue, the ECU will need to be repaired or replaced.

Clogged Radiator

A clogged radiator can also cause the temperature gauge to stay on cold. The radiator is responsible for cooling the engine by dissipating heat from the coolant. If it is clogged, the coolant may not be able to flow through the radiator, resulting in a reading that shows the temperature as cold. To fix this issue, the radiator will need to be cleaned or replaced.

Broken Water Pump

A broken water pump can also cause the temperature gauge to stay on cold. The water pump is responsible for circulating the coolant through the engine, and if it is not working correctly, the coolant may not reach the proper temperature, resulting in a reading that shows the temperature as cold. To fix this issue, the water pump will need to be replaced.

Fixes

How to Fix a Malfunctioning Temperature Sensor

To fix a malfunctioning temperature sensor, you will need to replace the sensor. The first step is to locate the sensor, which is usually located near the thermostat housing or the cylinder head. Once you have located the sensor, disconnect the wiring harness and remove the sensor using a socket or wrench. Install the new sensor and reconnect the wiring harness. Start the engine and check if the temperature gauge is working correctly.

If the issue persists, you may need to check for trouble codes using an OBD-II scanner. The scanner will provide a code that can help diagnose the problem further. If you are unsure how to proceed, consult the repair manual for your car or seek the help of a professional mechanic.

How to Fix a Low Coolant Level

To fix a low coolant level, start by checking the coolant reservoir or radiator. If the level is low, add more coolant to the system. Make sure to use the correct type of coolant specified in the owner’s manual. Check the coolant level regularly to ensure it stays at the proper level. If the coolant level continues to drop, there may be a leak in the system, and you should have it inspected by a professional mechanic.

How to Fix a Broken Thermostat

To fix a broken thermostat, you will need to replace it. Start by locating the thermostat housing, which is usually located on the engine block. Remove the housing and the old thermostat. Install the new thermostat and housing gasket, making sure to align it correctly. Reinstall the housing and fill the cooling system with coolant. Start the engine and check if the temperature gauge is working correctly.

How to Fix a Faulty Heater Core

To fix a faulty heater core, you will need to have it repaired or replaced. Start by draining the cooling system and removing the heater core from the dashboard. Inspect the core for damage or leaks. If it is damaged or leaking, it will need to be replaced. If it is clogged, it can be cleaned using a radiator flush solution. Reinstall the heater core, fill the cooling system with coolant, and start the engine. Check if the AC and temperature gauge are working correctly.

How to Fix a Blown Fuse

To fix a blown fuse, locate the fuse box in your car, usually found in the engine compartment or under the dashboard. Use the diagram on the fuse box cover or owner’s manual to locate the fuse for the temperature sensor or gauge. Replace the blown fuse with a new one of the same amperage. Start the engine and check if the temperature gauge is working correctly.

How to Fix a Faulty Engine Control Unit

To fix a faulty engine control unit, you will need to have it repaired or replaced. Start by locating the ECU, which is usually found in the engine compartment or under the dashboard. Disconnect the wiring harness and remove the ECU. Install the new ECU and reconnect the wiring harness. Start the engine and check if the temperature gauge is working correctly.

How to Fix a Clogged Radiator

To fix a clogged radiator, you will need to clean or replace it. Start by draining the cooling system and removing the radiator from the car. Inspect the radiator for damage or leaks. If it is damaged or leaking, it will need to be replaced. If it is clogged, it can be cleaned using a radiator flush solution. Reinstall the radiator, fill the cooling system with coolant, and start the engine. Check if the temperature gauge is working correctly.

How to Fix a Broken Water Pump

To fix a broken water pump, you will need to replace it. Start by locating the water pump, which is usually found on the engine block. Drain the cooling system and remove the drive belt from the water pump. Remove the old water pump and install the new one, making sure to use a new gasket. Reinstall the drive belt and fill the cooling system with coolant. Start the engine and check if the temperature gauge is working correctly.

Conclusion

In conclusion, there are several reasons why the car’s temperature gauge may stay on cold and the AC may not be working. These issues can range from simple fixes like a blown fuse or low coolant level to more complex problems like a faulty engine control unit or broken water pump. It is essential to diagnose the issue correctly to avoid further damage to the engine or cooling system.

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