Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. What Sensors in the AC Tell the Car If the System Is Working or Not?

What Sensors in the AC Tell the Car If the System Is Working or Not?

ac malfunction sensor

The average car today contains a bewildering range of sensors that feed information to various computers to monitor everything from air intake to emissions and engine timing. Your car’s air conditioning system also contains a couple of sensors that manage operation. However, unlike oxygen sensors, MAP sensors and others on your car, they don’t feed information to the computer. You can’t “pull a code” on an air conditioner malfunction.

Air conditioning components

There are two primary components that manage the operation of your car’s air conditioning system. The first and most important is the AC compressor. This component is responsible for pressurizing the system during operation. It also adjusts based on your input – when you change the temperature in the cabin through the HVAC control panel. The clutch operates the compressor based on your settings (but it doesn’t really “sense” whether the system is working or not).

The second component is the clutch cycling switch. This is a safety switch designed to keep the system off if there is not enough refrigerant for safe operation. It’s also designed to monitor the temperature inside your car’s evaporator core to ensure that they don’t drop low enough to freeze the entire core (which would stop AC operation).

Both of these components play a role in temperature monitoring and control, but neither of them communicates this information to the car’s computer. Diagnosing an automotive air conditioner problem will require a professional diagnosis of the symptoms (blowing hot air, not blowing at all, noise from the compressor, etc.), and then a complete inspection of the entire system coupled with a check of refrigerant levels, often with a special UV dye to detect leaks.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


More related articles

Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...
P2159 OBD-II Trouble Code: Vehicle Speed Sensor B Range/Performance
Diagnostic Trouble Code (DTC): P2159 P2159 code definition Vehicle Speed Sensor B Range/Performance...

Related questions

Q: My air conditioning stopped cooling the air in my 2010 Toyota Corolla

It is statistically unlikely that you had, at the same time, BOTH a leaking condenser and a leaking compressor on a 6 year old vehicle with only 50,000 miles. Indeed, the fact that after replacement of those two parts, the...

Q: When hot outside, bad odor from vent when on

It is possible that your evaporator may have fungus growing on and it's so thick that the cleaners you are running are of no use. In extreme cases, the evaporator will actually need to be replaced in order to get...

Q: Can running the blowers for the AC with the engine off drain the battery?

The problem is although the current draw over 45 minutes might be "low", your battery might be weak, meaning it could have a bad cell and a low reserve capacity. It doesn't take much to "drain" a weak battery. A...