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Ambient Air Temperature Sensor Replacement Cost

Know what price you should pay to get your vehicle fixed.

The average cost for an ambient air temperature sensor replacement is between $56 and $115. Labor costs are estimated between $26 and $78 while parts are priced between $30 and $37. Estimate does not include taxes and fees.
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What is an Ambient Air Temperature Sensor?

Air conditioning systems are forced to operate in the range of their environment, and computer controlled air conditioners are forced to operate in two environments. The ambient temperature, or the outside air temperature, is monitored by the ambient air temperature sensor, while the in car temperature sensor measures the temperature in the cabin of the vehicle. These two measurements help the control module for the air conditioning system adjust fan (blower) speed and air conditioning compressor operation in order to maximize the cooling of the vehicle as compared to conditions.

How does an Ambient Air Temperature Sensor work?

When the ambient air temperature sensor is cooled down, it raises resistances, so the reference voltage received from the control module will return to the control module much lower in voltage. This will inform the control module that the outside air temperature requires little activation of the air conditioning compressor once the inside temperature has reached the desired user setting. However, a scorching summer day in the southwest United States will heat the ambient air temperature sensor, causing the signal voltage to return to the control module nearly uninhibited. This tells the control module that even once the interior is at the desired temperature, as set by the user, the air conditioning system will still need to work very hard to maintain that temperature. Through small adjustments in blower motor, air conditioning compressor function, and blend door function, the control module will use these two sensors to eventually bring the inside of the vehicle to a constant desired setting.

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What are the symptoms of a bad Ambient Air Temperature Sensor?

There are one of three symptoms to be noted if the ambient air temperature sensor fails. Either the vehicle will become far too warm, or far too cold inside the vehicle. This is caused by the inability of the control module to adjust to outside temperature, and the resistance in the circuit will likely remain the same. In most cases, if the resistor fails, the air conditioning system will not function at all. This is because there is not likely to be current passed back to the control module if ambient air temperature sensor has failed internally. Finally, since many ambient air temperature sensors are used by other modules, the check engine light may display, and the temperature reading on the instrument cluster or rear-view mirror may display blanks or a set of dashes.

Can I drive with a bad Ambient Air Temperature Sensor?

Vehicles with a bad ambient air temperature sensor can be driven indefinitely, but the comfort and, depending on the climate, safety of passengers should be considered. In extremely hot climates such as deserts, not having an air conditioner in the vehicle could be considered a risk factor for children and seniors.

How often do Ambient Air Temperature Sensors need replacement?

Electronic switches fail at random, and many vehicles will need various sensors and switches replaced within 150,000 miles or so. However, due to the simplicity of the ambient air temperature sensor, it is not likely that the sensor will require replacement except in the event of a collision which causes direct damage to the sensor. This is because many of these sensors are mounted on the front of the vehicle, directly behind the bumper cover where there is little protection. Aside from that, the failure of this sensor will be totally random.

How are Ambient Air Temperature Sensor issues diagnosed?

The ambient air temperature sensor is only one point of failure in the air conditioning system, and any servicing technician must diagnose the air conditioner as a whole. Refrigerant pressure must be checked on the high pressure and low pressure side, which will normally provide an understanding of where the problem may be, and where the technician should investigate further. Keep in mind there are electronic components that must be checked with computerized scanning equipment to verify accuracy and functionality, and the ambient air temperature sensor definitely falls into that category. Since this sensor is just a resistor, it can be removed and checked by connecting a multimeter to the pins on the electrical connection, and heating or cooling the sensor while watching the resistance for proper movement through its range.

How are Ambient Air Temperature Sensors replaced?

Replacement is as simple as accessing the ambient air temperature sensor, disconnecting the battery, removing any securing clips, brackets or fasteners, and disconnecting electrically from the main wiring harness. Then, the new sensor can be connected electronically and secured to the vehicle in the most convenient order. Reconnecting the battery is needed to test the functionality of the system.

RepairPal Recommendations for Ambient Air Temperature Sensor issues

we recommend avoiding the use of any off-the-shelf air conditioning repair additives, as these additives are only temporary fixes, if they work at all, and can cause damage to air conditioner refrigerant evacuation machines. Also, never attempt to vent refrigerant into the air, as this is harmful to the environment, and can cause chemical burns. If the system is overcharged, you will need the refrigerant to be recovered by a trained and certified technician.

What to look out for when dealing with Ambient Air Temperature Sensor issues

Older vehicles were made with ozone-depleting, or non-environmental friendly refrigerants, and releasing any refrigerants into the atmosphere is illegal. Federal law requires contained evaporation and disposal of refrigerants, and this requires fairly expensive machinery/tooling. Federal law also states that the older types of refrigerant be replaced with a more environmentally friendly version when the air conditioner service is performed. This will likely require several components, and seals to be replaced to ensure compatibility with the new refrigerant. Due to the nature of air conditioning systems, adding refrigerant is not advised without measuring the high pressure and low pressure side of the system simultaneously, as the pressures may not be affected on both sides of the system.

Can I replace the Ambient Air Temperature Sensor myself?

As easy as the sensor may be to replace, the air conditioning system must be tested prior to replacing the ambient air temperature sensor. In many cases, the sensor will not be the issue, so testing will prevent unnecessary cost and frustration. Air conditioner repair is seldom achievable at home, and will require expensive evacuation equipment, a manifold and gauge set, creating a vacuum in the system, and charging the system. Aside from the lack of equipment that most DIYers will face, there is a danger of harm to person, equipment, and the vehicle when repairs or diagnostics are performed incorrectly. When it comes to servicing the air conditioner, it is best left to the pros. However, if the sensor is known or proven faulty, replacement is a breeze for just about anyone, as long as the location of the sensor can be found.

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