Car Sputters When Air Conditioner Is On

Helen Skeates
Helen Skeates
15 min read

Do you ever wonder why the air conditioner causes your automobile to sputter? Plenty of things could be going wrong to cause this issue you’re having right now. Due to their compact size, car air conditioners are more prone to malfunction than stationary units. Possible causes include insufficient refrigerant, a faulty belt, or an air conditioner’s failing compressor. This article is for you if you’re having this issue. Exactly why, therefore, does turning on the car’s air conditioning cause it to sputter?

The Air Conditioning Shouldn’t Normally Keep the Idle Speed Down

When you turn on the air conditioning, does your automobile have a choppy idle?

When the air conditioner is turned on, it is common for there to be a temporary drop in speed. When the air conditioner’s clutch is engaged, the compressor must work harder, which increases fuel consumption. However, the PCM of the vehicle should raise the idle speed again.

If you lose over 200 rpm and idle speed doesn’t rise again, then there’s a problem.

10 Reasons Why Car Sputters When Air Conditioner Is On? - Honda The Other Side

Possible Causes of Rough Idle When the Air Conditioning is On

If you lose over 200 rpm and idle speed doesn’t rise again, then there’s a problem.

  • Concern should be raised if idle speed drops by more than 200 rpm and doesn’t recover.
  • Unclean throttle body
  • It could be a problem with the condenser or air conditioner’s fan.
  • Depending on the model, other malfunctioning systems or components

Explore the most frequent explanations in the following areas. Simple at-home diagnostic or troubleshooting steps are included in or linked to throughout each section. The diagnostic tool can shorten the time required to repair your car and, in some cases, reduce repair costs.

Reason For Sputter In A Car Air Conditioner When It’s On

First, understand that this problem is not localized in any one system but rather the end outcome of a confluence of causes. First of all, running an air conditioner puts a burden on the engine (the engine controls the compressor). As a result, low-pressure gaseous refrigerant can be compressed into high-pressure liquid and used in your cooling system.

Before you can diagnose the issue with your air conditioner, you need to know what goes on inside of it. Information about why your automobile sputters when the air conditioner is on has been compiled by us. Please read “Car sputters while air conditioner is on” before calling a mechanic. These are the results, by the way:

Reason #1. Faulty IAC valve

It is the idle air control (IAC) valve, controlled by the PCM (power system control module), that is responsible for regulating engine idle. A predetermined amount of air is allowed to escape through the throttle plate thanks to IAC. Adding more air to the combustion chamber helps when starting a cold engine. When additional demands are placed on the engine, as when the air conditioner or defrost is turned on, this feature helps the engine speed up to meet those demands.

Carbon deposits surrounding the IAC valve, the throttle passage, and IAC engine failure are the most common issues.

Simple IAC engine testing is inspecting the throttle bypass port and the IAC valve for signs of carbon buildup. If your vehicle is experiencing issues with its electric cooling system, you can use this article as a resource.

Reason #2. Dirty throttle body

The throttle body could be unclean, causing the automobile to idle erratically. It is the throttle body’s job to control how much air the engine receives. If the engine gets dusty, it will not work properly. A filthy throttle body may result in a slower idle speed when using air conditioning. And keeping the throttle closed when idling by commanding the computer to restrict airflow.

However, if the throttle plate and orifice are unclean, the air conditioner won’t be able to pull enough air through. Vehicle and driver efficiency can both benefit from a clean throttle body.

All those who have experienced erratic engine operation, risky driving, or diminished performance can benefit from this solution. The new car is still brand new, after all. As soon as you turn off the engine, the hot gases and any unburned fuel will rise to the top.

Reason #3. Complications with the cooling and condenser fan

High pressure and erratic idle speed can be caused by a faulty cooling fan or condenser. If your condenser or cooling system has a variable fan speed, check that it is functioning normally. In addition, a rapid circuit inspection can be performed using just a few basic checks. Also, you can investigate the most common issues related to cooling fans. See this article for the guide.

Reason #4. Problems with the distributor and ignition

Check the cap and rotor on your used dealer automobile. The lid’s middle and ends will degrade, accumulate carbon deposits, and catch fire. This reduces the likelihood of a spark plug exploding due to its powerful sparks. Carbon traces and cracks should be looked for in the manifold cover and terminals.

Through carbon traces, it will conduct electricity to the earth. Black dispenser covers may need bright light to reveal carbon traces. Ensure the lid is secure by checking it thoroughly.

200-6000V rotor terminal outer cap tip Carbon deposit and wear make it hard to produce powerful sparks. Look for burns, damage, and gaps in the rotor tip. Alternately, you could just switch out the final piece. The spark plug and its wire must be inspected. When it comes time to service your car, make sure to follow the manufacturer’s guidelines for checking the rotor, spark plug wire, and spark plugs. Please refer to your vehicle’s maintenance manual or owner’s manual if you have any questions.

Reason #5. Adjust idle speed

If you haven’t already done so, try experimenting with different idle speeds to see if that helps. When driving an older car with a carburetor, you can adjust the idle speed. As a matter of fact, this is a common practice for many carburetors. If necessary, adjust the idle speed screw or examine the idle speed solenoid valve. Then do what it says to do in the car’s maintenance handbook.

The idle speed of a modern car is controlled by the powertrain control module (PCM), which receives data from airflow, throttle position, and temperature sensors. Manual controls may be available in some releases.

To find out more, look at the engine compartment decals or the manual that came with your vehicle. Sensors used by the PCM to determine the idle speed can be inspected. Throttle position sensors (TPS), mass airflow sensors (MAF), and engine coolant temperature sensors (ECT) are a few examples. When your system is running at low speeds, such as before you switch on the air conditioner, sensors or actuators on the periphery might not be a concern. The malfunction indicator light (commonly known as the “check engine light”) could also be absent.

10 Reasons Why Car Sputters When Air Conditioner Is On? - Honda The Other Side

How to Maintain Your Car’s Air Conditioner

Inspecting The A/C System & Keeping It Running

In the northern climes, automobiles’ air conditioning systems need to be run for around ten minutes once a week during the cooler months. As a result, the oil will be recycled throughout the system, avoiding the seals from drying out (which would cause the Freon to leak out.) Furthermore, regular use of the air conditioner can help prevent the growth of mold and mildew in the air chambers, which is a common source of musty scents (or worse).

Even if you only use your AC sometimes, you should still check it over to make sure everything is in working order. Almost anyone is capable of doing this. The air conditioning condenser, which is situated in front of the radiator, is the first component of the cooling system to be examined. The condenser is responsible for transforming the gaseous Freon back into a liquid state (it condenses). Remove any obstructions, like a clogged bug screen, from the condenser to ensure proper airflow. The efficiency of the air conditioner will suffer if the condenser is obstructed. A high-pressure nozzle attached to a garden hose makes quick work of cleaning the condenser.

Checking The Engine Fan And Fan Belt

Next on the list is inspecting the mechanical or electrical components of the engine fan. Electric radiator fans are required to operate continuously whenever an air conditioner is switched on. High pressure in the system caused by the fan not working might cause the hoses to burst, releasing Freon and oil. When the air conditioner is on, just one of the two electric fans (if present) needs to be operating. If you’re driving and you notice the temperature of the air flowing out of the vents is low, but it climbs significantly when you let the engine idle, it’s likely that your cooling fan is broken.

If, on the other hand, you have a mechanical clutch fan with a thermostat at its core, the fan’s clutch should tighten and its blades should spin more quickly as the air passes through the condenser and the radiator warms up. The fan clutch can be checked for wear with a simple test. Reach in while the engine is cold and turned off and manually spin the fan. It is appropriate for the fan to rotate at will. When the engine is hot, you will experience some resistance when turning the crank. If the fan is loose and free to spin when the engine is heated, the fan clutch is probably broken. As mentioned in the previous paragraph, a faulty clutch fan can be detected if the air from the vents is cold when driving but noticeably warmer when the engine is idling.

The next step is a visual inspection of the fan belt. Check the belt’s underside for any signs of cracking. The belt has to be changed if there are any splits in it. When replacing the belt on an older car, it is important to use a belt tension gauge to ensure that the belt is not under too much tension and damaging the vehicle’s drivetrain. Newer vehicles avoid this issue altogether because to the inclusion of a spring-loaded belt tensioner that automatically adjusts the belt’s tension to prevent early failure of the driven components.

Checking Operation

Now is a good time to inspect the condition of the air conditioner. Turn the thermostat all the way down and the fan all the way up before starting the engine. To rotate the internal parts of the air conditioner, a clutch is located at the front of the device. The compressor’s clutch and drive pulley should rotate in unison if you give it a close look. It is common for the clutch to engage and disengage every 20-30 seconds. It’s a good sign that the system needs more Freon if the clutch turns on and off rapidly every few seconds.

What You Do Need A Professional For

Ten to fifteen percent of the Freon in air conditioners might leak out every year. Here is where you should seek the assistance of a qualified expert. There is a recommended amount of Freon that should be present in every air conditioner. A label can be found on the top of the radiator housing, the bottom of the hood, or the evaporator compartment. This label specifies the exact type and quantity of Freon (in ounces and pounds) that must be present for the system to function properly. Because oil is often carried along with the Freon, a leak can often be located. Leakage is likely present if greasy or black residue can be seen on fittings or hoses. Leak detection dye or an electronic leak detector are two alternative options.

Adding more Freon to a system that is only slightly low is not recommended. Adding too much Freon to a system might damage the compressor or lead to dangerously high pressure, which can cause hoses to burst, because it is impossible to determine how much Freon is already there. To properly recharge an air conditioning system, one must empty the entire system and then refill it with the specified amount of refrigerant as indicated on the label. In order to recharge an air conditioner, you will need a vacuum pump and a set of air conditioning gauges. Since water boils at a vacuum of 17 inches at sea level, increasing the vacuum pressure on a system beyond that point will result in the removal of moisture by boiling it. Twenty to thirty minutes of continuous operation of the vacuum pump is recommended to eliminate any possibility of moisture contamination. A low-pressure gauge with a vacuum reading can let you know just how much suction is being drawn. After 20-30 minutes of purging air from the system, the technician flips a switch to see the low-pressure side of the vacuum gauge in complete darkness. Seeing if there is a leak in the vacuum would require waiting around five minutes. It is generally accepted that if a system can hold vacuum, it can also hold Freon.

DIY Recharge Kits?

Stay away from the do-it-yourself recharge kits sold at most hardware stores. Keep in mind that the absence of Freon isn’t the only possible explanation for a broken air conditioner. In the event that the issue with the system wasn’t caused by low Freon levels, what would happen then? Adding more Freon to a system that is already full can result in the damage of the compressor or the rupture of system hoses. The sum total of those factors is negative.

Careful attention must be paid in tinkering with an air conditioner. If a line does burst and Freon gets in your eyes, it can freeze them instantaneously and can cause blindness, thus you should always wear safety glasses. Oil charge kits are available at auto parts stores, but their application requires expert knowledge. When there’s an excess of oil in the system, performance suffers. In most cases, oil is unnecessary unless some of the system’s components need to be changed.

Is Dripping Water A Sign?

Water will drip from the undercarriage when the air conditioner is on. It’s usual for the evaporator to release some condensation into the cabin after the passengers have been evacuated. Condensation drains may be clogged if water is entering the passenger side floor from above rather than below the car. Mold and fungus can grow in stagnant water and eventually block the drain or hose leading outside. Most of the time, this will require a thorough cleaning of the vehicle’s undercarriage.

Finally, the most frequent query I receive is, “why does it take so long for the air to get cold?” The sun’s heat radiating off the dashboard is just one of several factors making it necessary to have a fully functional air conditioning system. A few minutes are needed for the dashboard to cool down. Humidity removal also improves the performance of a system. You can watch it drip down the vehicle’s undercarriage over the course of a few minutes. Most modern automobiles also feature a cabin air filter, the restriction of which can impede the flow of air through the dashboard. This filter needs to be swapped out a few times a year at minimum.

10 Reasons Why Car Sputters When Air Conditioner Is On? - Honda The Other Side

Prevent waiting in line at the repair shop by having your air conditioner checked out and serviced well in advance of the summer season. When people are uncomfortable, they often spend more money than is reasonable. Stores that insist Freon depletes with time and must be refilled selling you a load of hooey. Quick lubes often recommend getting your air conditioner recharged as an easy and successful up-sell. More likely than not, they are merely adding Freon and not following the steps outlined here to properly recharge the system.

Final Thoughts

So it explains why your automobile sputters while the air conditioner is on. Always double-check any potential issues with your vehicle, and if you’re still unsure, see a professional mechanic. In other words, are you interested in continuing to read? Do you know why a car’s air conditioning only kicks on when it’s moving? If that’s the case, you might also want to read this. Whatever the case may be, I appreciate it.

Helen Skeates

Helen Skeates

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