Skip the auto shop - Our mechanics make house calls

What Typically Causes the Heating or AC to Stop Working?

heating and AC

While both the heating and AC are connected - to an extent - within your car, they’re actually separate systems. Your car’s heater uses heated engine coolant to warm the air that is blown into the cabin, while the air conditioner uses a compressor driven by the engine, combined with both high pressure and low pressure lines, special refrigerant and many other components.

Potential problems with your car’s HVAC system

The potential issues here vary whether your heating has gone out or your car’s AC system is on the fritz.

Common reasons for the heating system not to work include the following:

  • Low coolant
  • Air in the coolant system
  • Malfunctioning heater core
  • Failed (or failing) thermostat

The potential issues with the AC system are different, and include:

  • Low refrigerant (will generally blow cool, but not cold)
  • Damaged compressor
  • Damaged compressor clutch
  • Damaged expansion valve
  • Damaged evaporator
  • Worn or stretched serpentine belt (required to operate the compressor and clutch)

As you can see, both systems are very different. However, if you’re experiencing problems from the HVAC controls, then it’s possible that the same issue will prevent both your air conditioning and heater from working. For instance, a failed blower motor won’t be able to blow air into the cabin. A failed fan switch will make it impossible to adjust the blower fan speed. There are a number of other potential issues, ranging from a failed relay to a blown fuse to a short in the wiring.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

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.

GET A QUOTE

More related articles

How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P0291OBD-II Trouble Code: Cylinder 11 Injector Circuit Low
P0291 code definition When your vehicle’s PCM registers the P0291 code, it means that a voltage reading came from the fuel injector circuit – for cylinder number 11’s fuel injector –...


Related questions

Q: Their is a hole in the Heater Box

If you are referring to the "heater core", which is the metal assembly under the dash that looks like a mini radiator and through which heated coolant flows, for your make and model that part costs anywhere from $75 to...

Q: Various problems with driver's side of car.

Looking at the wiring diagrams there is no correlation or common issue that tie together the AC, wipers, and speaker issues. For the heat issue where the drivers heat is staying there is either an issue with the front mode...

Q: Fan blower motor not working replaced resistor and blower motor but I don't know we're the fuse or relay is located

The fuse and relay is in the power distribution center which is mounted under the hood on the left side of the engine compartment. Remove the top cover and look on the under side of the cover. You will see...