Hey, Why Does My Car's AC Sometimes Work And Sometimes Don't?

Hey, Why Does My Car's AC Sometimes Work And Sometimes Don't?
The modern-day air conditioning system is computer-controlled. There is a multitude of sensors, switches, and motors that control the amount of cooling that the air conditioner puts out inside the vehicle. When these sensors start to act up, they can randomly affect the interior temperature. The interior temperature may fluctuate widely. Diagnosing these systems often requires the use of very dedicated specific equipment.

Is Your Car's AC Inconsistently Working?

It’s only working sometimes because the cabin air filter is too dirty, the “mode” door motor is faulty, or the variable compressor is stuck. Alternatively, the following parts might intermittently malfunction: the ac control unit, the ac high-pressure switch, and the evaporator temperature sensor.

Are you experiencing an unpredictable AC system in your car? One moment, it's working fine, and the next, it's not cooling at all?

Don't take this issue lightly! Ignoring it could put your safety at risk and lead to costly repairs. Instead, consider discussing with a professional to address the problem immediately.

Doing so ensures your vehicle remains in good working order, and you can drive it carefree, knowing your AC system functions consistently. Don't let a minor AC issue become a significant problem that could have been avoided with timely maintenance.

Let's Get To The Bottom Of It!

  • Q: Is the car's AC air coming from somewhere apart from the vents?

    Your car's air conditioning system has several doors in its box that merges hot and cold air and direct it to where it must go. The Mode door motor is usually connected to a lever mechanism that controls multiple doors. However, if the Mode door motor gets miscalibrated, it causes air to come out of the wrong vent or not come out at all. This happens due to an intermittent connection that causes the motor to function only sometimes or stall, directing air to the wrong location.

  • Q: Is the temperature coming differently from opposite sides of the car?

    The AC control unit in your car is often built into the same panel as the fan and temperature knobs. Over time, the switch on this panel can wear out. When a switch wears out, it sends the wrong or no signal. This can cause problems for switch-controlled components, like the blower and air door control motors. For example, if one of the temperature switches is malfunctioning, it sends the wrong signal to the blend door on one side, causing the temperature on that side to be different.

  • Q: Is the temperature from the air coming out of the vents erratic?

    The AC high-pressure switch is essential to keep your car's air conditioning system running smoothly. It's responsible for monitoring the pressure on the "high" side of the system. If the high side pressure is out of range, the pressure switch signals to the climate control module about a problem with the AC system. If this happens, the compressor shuts off, meaning no cooling comes from the climate control system. Sometimes, however, the pressure switch can be erratic. This means it may shut the AC system off even if the pressure is within the normal range.

  • Q: Does your air conditioner stops for a long while before working again?

    The evaporative temperature sensor is a small but essential part of your car's air conditioning system. It's located in the airbox before the evaporator core, and it determines the core's temperature. This information is crucial for maintaining your AC system's efficiency. Another essential function of the temperature sensor is to alert the climate control module if the evaporator freezes over. If the sensor registers a temperature colder than the actual temperature of the evaporator, the climate control module thinks that the evaporator is frozen. This causes the AC system to shut down until the temperature rises.

All related issues checked?

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Hey, Why Does My Car's AC Sometimes Work And Sometimes Don't?

Vehicle Health Inspection Proof

Explore the following typical inspection results that show a potential cause for the symptom and select the one you believe is similar to your vehicle's issue.

Dirty cabin air filter

The proof image shows the restricted cabin air filter, highlighting the importance of regular maintenance and replacement of filters to ensure the efficient operation of the air conditioning system.

A customer brought their vehicle to the shop and mentioned the air conditioning was not cooling as usual. They thought the blower motor was wearing out because the air from the vents did not feel as sturdy.

During the test drive, the technician noticed the air conditioning was not cooling as expected, and the air from the vents was weak. So the technician conducted a vehicle health inspection to determine the cause of the issue. After checking the components, they found that the cabin air filter was clogged, reducing airflow.

The cabin air filter purifies the air before it goes through the evaporator core. However, over time, the filter clogs with dirt, mold, and debris, restricting the airflow and reducing the cooling performance.

The technician recommended replacing the cabin air filter to restore the airflow to normal. After replacing the filter, the technician checked the air conditioning system's performance. First, they used an AC machine to check the pressures in the air conditioning system and found that they were running in the normal range.

They also checked the temperature coming out of the center to vent with the AC on high and found that the vent temperature was at 38°, indicating that the AC was performing efficiently.

Does the issue look like this? if not accessible your shop will document it

Typical Fixes to Address the Cause(s)

The following chapters bases themselves on experiences from our auto repair shop; we'll describe related problems' causes and fixes.

"Cabin air filter replacement" fixes "Dirty cabin air filter"

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Sometimes a problem is more challenging to describe than it initially looked like. If you are not sure your problem is described by this article, please find below similar vehicle symptoms, which might describe better the issue you are experiencing.

Other things your auto repair shop might talk about:

Car AC sometimes works sometimes it doesn't. Car air conditioning. Electric blower motor. Air compressor. Air blowing.

Is AC Only Work Sometimes
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