Skip the auto shop - Our mechanics make house calls

Q: Message on my dash where speedometer is says ac off becasue engie temp is too high

asked by on

I got a message today that said my ac is off because engine temp is too high and my temp gauge doesn't seem to be working, it shows all the way cold. When I shut my car off it sounds like the fan or something is still running. I am wondering if this could be my thermostat.

My car has 107000 miles.
My car has an automatic transmission.

It sounds as if your car has put itself into a default mode to protect itself form overheating. The fact that the gauge shows it is cold indicates there is likely a problem with the coolant temperature sensor. When this system fails, the PCM (powertrain control module) assumes the car is overheating to protect it from getting too hot and damaging the motor further. The A/C condenser is mounted on the front of the radiator and adds heat to the cooling system, so it is turned off to limit any extra heat sources from contributing to the lack of ability to cool the car sufficiently.

I would begin diagnosing this by connecting a scanner and inspecting the data. Most likely you will see the CTS (coolant temperature sensor) has failed. Keep in mind, wiring to the CTS could be damaged and causing this problem as well. The CTS data should show a temperature that reflects the temperature of the motor. If you have been driving it recently, it will be in the 180F to 200F degree range. If you check the data with the engine cold, the data should reflect the ambient temperature. It is common for a failed sensor to show a reading of -40 degrees Fahrenheit. If you want to have the AC system and related components inspected, a technician from YourMechanic can come to your home or office to diagnose your car and let you know what needs to be repaired.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  • Home
  • Questions
  • Message on my dash where speedometer is says ac off becasue engie temp is too high

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: I have an error code P2159 popping up on my Hyundai Sonata. I want to know exactly which speed sensor to replace driver or passenger

Hey there. If your Sonata does not have ABS (not sure any exist without ABS), the wheel speed sensor input is from the physical wheel speed sensor, located on the passenger front wheel hub assembly. If your Sonata has ABS...

Q: Leak caused by corrosion on throttle body terminal

Hello. There are some fairly sensitive electronics inside the throttle position sensor (TPS) housing. They are also not engineered to be easily disassembled for repair either. Unless you are quite experienced at unsoldering and soldering printed circuit board connections, I...

Q: My a/c was going from cold to warm and back to cold. Then went hot permanantely. The dealer looked at it and said the compressor i

Hello. I suggest to ask the dealer staff to inform you why the compressor needs to be replaced. Ask them if the compressor is seized up, if it's leaking oil around the main bearing shaft seal or just the compressor...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.