Q: My car is moving the Ac get cold if I stop the signal or park the Ac get hot

asked by on

My car is moving the Ac get cold if I stop the signal or park the Ac get hot
My car has an automatic transmission.

This is a classic symptom is very common. Most likely the cooling fan for the condenser is not turning on allowing the high side of the A/C system to get to hot. This reduces the cooling capacity of your system. The cause can be the fan motor, a cycling switch, or a temperature switch depending on the design of the system in your car.

After looking at the wiring diagram of your Kia Optima, it appears the fan is turned on and off by the PCM (Powertrain Control Module). The PCM receives a signal from a pressure transducer. The transducer lets the PCM know how hot the condenser is and determines when the fan should be turned on. Between the PCM and the fan motor is a relay. Relays are excellent points to diagnose a system such as this.

From the relay you can supply power to the fan motor with a jumper wire and see if it turns on. If it does, you know it is either the relay, the PCM (not common), and the pressure transducer. You can run the car until the A/C system output begins to increase in temperature, then use a test light to see if the PCM is commanding the relay on. If it is, you need a relay. If not, you should begin by replacing the transducer. They are a common failure item, PCM’s rarely fail and are very expensive.

If you need some help with this, feel free to contact a certified technician, like one from YourMechanic. They’ll be able to diagnose the issue with your A/C and help you fix it accordingly.

Good luck!

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. My car is moving the Ac get cold if I stop the signal or park the Ac get hot

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: My dashboard lights,gauges,radio and power windows don't work. I can start my truck right up and drive.

Hello, thank you for writing in. Typically with the first symptoms you described I would direct you to check all of your fuses, focusing on the instrument cluster fuse. However considering the engine is showing signs of stress, you may...

Q: Q: Air conditioner blows warm air

There are many reasons for poor AC performance, from low refrigerant, to a failed compressor. I suggest you have an AC performance test performed on your vehicle to determine the cause. This test involves hooking up gauges to the A/C...

Q: Why is my 2010 kia forte sound like it is grinding when I'm driving but when I push the gas harder it stops?

Hi there. If your vehicle is emitting a noise when driving but when you apply more acceleration the noise goes away, then there could be an issue with the engine's lubrication system. Check the engine oil level and make sure...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.