HVAC REPLACEMENT: Symptoms of a Bad or Failing AC Thermistor

Mounted near the evaporator coils, an AC thermistor is a temperature sensor that monitors the temperature surrounding your unit. Once it detects changes in temperature, it signals your AC to turn on, then to turn off once the temperature drops to the level you indicated.

A thermistor is used in different ways. The thermostat used to monitor the temperature in HVAC systems has a highly sensitive thermistor. Your cell phone, car, microwave, refrigerator, and washing machine also have thermistors.

The changes in temperature that the thermistor detects can influence your equipment. With a faulty AC thermistor, the temperature in your home may become uncomfortable.

So it helps to be able to recognize the symptoms of a bad or failing AC thermistor, so you can get it replaced right away.

Symptoms of a Bad or Failing AC thermistor

1. The air conditioner blows only cold air for a short period

Before the thermistor goes completely bad, you’ll notice things starting to go haywire. A common symptom is your AC blowing only cold air for a short period.

2. Incorrect temperature readings 

Watch out for incorrect temperature readings. Due to age and regular use, there’s a dip in resistance accuracy in thermistors. But incorrect temperature readings may also be caused by thermal mismatch, improper handling, or excessive heat.

3. Impossible temperature fluctuations

If a thermistor isn’t operating as it should, there will be impossible temperature fluctuations. You may get an initial reading of 200 degrees, then notice the temperature would drop by 30 degrees, only to find it back to 200 again.

Temperature fluctuations may occur due to other reasons, but if they happen often, it’s highly likely that the thermistor isn’t properly working.

Testing your AC Thermistor

Testing your thermistor is a surefire way to determine if it’s indeed faulty. To get started, you’ll need a multimeter with an ohmmeter to measure thermistor resistance and any heating device such as a space heater or a blow dryer.

Once you have what you need, testing your thermistor is a straightforward process:

1. Take note of the thermistor’s current reading.
2. Set the resistance value to its rated value.
3. Apply heat with a blow dryer or space heater. Thermistors respond to the slightest changes in temperature, so there should be immediate resistance fluctuation. Otherwise, you need a new thermistor.

HVAC REPLACEMENT NEAR ME: AC Thermistor Replacement Service 

Do you recognize the signs of a bad or failing AC thermistor? Can’t tell whether or not it has malfunctioned?

Book a Good Guy and we’ll make sure your AC achieves maximum efficiency, and your home stays comfortable and safe. We’ll repair and maintain your system, so you avoid paying for a replacement before it’s necessary.

If a replacement is absolutely needed, our knowledgeable, experienced technicians can also help. We’ll provide custom HVAC solutions to turn your home into an oasis of comfort, with your unique needs and budget in mind.

Schedule your appointment through our exclusive Good Guys Home Services Mobile app or fill out our online form for faster service.