Updated at: 12-04-2023 - By: Helen Skeates

Consider a well-worn vehicle with a few niggling issues. It’s easy to miss them or brush them off.

The inefficiency or production of hot air, however, from your air conditioner is certain to be a source of frustration. The coolant level, the condenser fan, or the compressor could all be to blame.

The following article provides information to think about and potential solutions to the problem of an air conditioner that only functions while in motion.

Air Conditioner Only Works When Driving Causes

A/C Condenser Fan

The role of the condenser fan in a well functioning air conditioning system is to maintain a constant cool temperature.

Through the condenser, they are responsible for moving heat from the indoor to the outside unit. Consequently, the function of the air conditioner’s condenser fan is crucial. There could be issues if they don’t function properly.

Air Conditioner Only Works When Car Is Moving - What's Wrong? - HVACseer.com

If your air conditioner isn’t cool enough or isn’t turning on at all, it could be the first sign that something is wrong. When vehicles are idling, they are less efficient than when they are moving.

However, when driving at high speeds or on the highway, the condenser receives sufficient airflow on its own, and a cooling fan is unnecessary. There is no airflow when the vehicle is parked, therefore the fan is crucial for maintaining a comfortable temperature inside.

Before doing anything more, make sure all of the connections and wiring for the fans are secure. It’s possible that they’re unplugged or connected into the wrong outlet. Similarly, you should test the fuses and relays that control the power.

If your fans aren’t working and there isn’t an obvious fault, they’re probably dead. Thermostat switch or motor failure could be to blame if your air conditioner’s condenser fan stops working. Therefore, they will not become heated enough to trigger the fan.

A/C Condenser Blockage

If the fan is functioning properly and the car is still too warm when parked, you can look elsewhere for the cause of the problem.

You can inspect the condenser itself, in addition to the fan, if you have an air conditioner. Contact and accumulated dirt might cause them to become clogged over time if they aren’t cleaned. When you find the source of the issue, the first thing to do is to clean these components. Restarting the air flow with a thorough cleaning.

It is important to thoroughly clean the condenser when it becomes clogged. If you wait too long, you may need to replace the entire air conditioning unit.

A coil’s ability to function properly is diminished if dirt and dust are allowed to build up in it over an extended period of time. Like condensers, they require regular cleaning to remove debris and filth.

You should do these things as often as you can while you have the car. Preventative maintenance is the most effective way to lower the number of irritants in one’s driving experience.

Faulty or Worn Condenser Parts

Due to frequent blockage, condensers’ performance suffers, resulting in subpar overall system efficiency. The condensers only turn on and off briefly, and the A/B systems are inefficient even when running at full speed.

Long-term damage will be done to several components. You should thus consider upgrading the system or replacing specific components.

There are a number of components that make up the condenser. These parts are susceptible to dirt and wear and can reduce the condenser’s efficiency over time.

You can do things like clean individual components or the whole system. Additionally, if necessary, they can be replaced.

If you run across problems, you may want to think about fixing them or getting new ones:

  • If your machine is malfunctioning, you should get a new engine. However, not every motor will work in your car. You should check your previous engine description for precise numbers, as doing so might assist you avoid making any unintended mistakes.
  • The malfunctioning switch: This information is readily available whenever a suitable replacement is sold. It’s also very simple to make a change.
  • If the capacitors fail, they may be simply located and swapped out like a faulty switch.

Those are, nevertheless, elementary mistakes. There are situations when you come across more serious issues that prevent the system from functioning.

  • It’s important to keep the condenser free of debris like dust and scrap metal. They trigger a complex error that is difficult to fix. It seems like you need a new condenser, or maybe even a new air conditioner.
  • Coil: It is highly difficult and uncommon to replace a segment of the loop. Because of the effort, expense, and difficulty involved. People typically change out the complete lock on their air conditioner. Therefore, this action will result in financial and time savings.

Air Conditioner Compressor

The compressor is the brains of the air conditioner system of an automobile. When the system is underperforming, there is usually more than one problem causing it, therefore spotting the issue right away will be challenging.

Since the compressor is where the cooling coil is located, the wiring isn’t any more impressive or effective while the vehicle is operating than it would be with the compressor located elsewhere.

In cases like this, the compressor is typically the first thing checked by mechanics. If your air conditioner stops blowing cool air and starts blowing hot air, the compressor may be malfunctioning or needs to be replaced.

This malfunction is due to the lack of available refrigerant or a disruption in its transport.

This inefficiency becomes most apparent while the car is at rest, especially when traveling on highways when fresh air is not constantly being drawn into the cabin.

Noise is the second possible indicator. The source of the noise is within the compressor itself. For this reason, it can be challenging to trace the origin of compressor noises. Pay close attention so that you can pick up on the specifics of the mistake.

You can also find out when the sound is being emitted by turning on the air conditioning. While the air conditioner is on, it may or may not be released. If the air conditioner won’t switch on and the noise keeps going, it’s not the compressor.

Low Coolant/Freon level

It is common knowledge that Freon is an AC refrigerant. They aid in maintaining an optimal engine operating temperature. Adapting to the weather is an integral part of keeping your vehicle’s engine in tip-top shape.

The engine may be kept cool and functioning properly with the help of the freon even if the ambient temperature rises dramatically. However, as the temperature outside drops, the engine can remain comfortably warm thanks to the freon.

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Therefore, the proper temperature-keeping operation will be less effective if the coolant level is inadequate. Your systems’ efficiency will suffer as well because of their reliance on the coolant.

The issue may become apparent when the automobile is running with no fresh air coming in.

It’s also possible to pick up on a problem with the clutch from the noise it makes. There should be a clutch noise when you turn on the air conditioner; if there isn’t one, the coolant level is probably low. For the simple reason that the clutch is activated by sensing the coolant level and releasing pressure on the compressor only when the level is high enough.

The condenser leak, which lowers the coolant level, is another possible explanation. It is more likely that the condenser’s components will wear out and fail physically, such as breaking, if the condenser is involved in a collision while the vehicle is in motion.

Leaks are never cost-effective and can end up costing extra money. Because of this, the air conditioner functions poorly. The difficulty lies in the fact that these mistakes will be hard to spot.

5 Benefits of Maintaining Your Car’s Air Conditioning System

1. Ensure Optimal Performance

Putting off routine maintenance on your car’s air conditioner can cause more complications and a drop in performance. Common issues with your air conditioner include leaks of refrigerant and dirty air filters. Regular maintenance by a trained professional will keep your car’s air conditioner operating at peak efficiency and head off any potential problems.

2. Minimize Costly Repairs

Auto AC maintenance is a long-term investment that pays off in lower energy bills and fewer breakdowns. Repairing a car’s air conditioner is more expensive than routine maintenance.

3. Foster Good Air Quality

The air conditioner in your car does more than just keep you comfortable; it also cleans the air and controls the humidity. If your car’s air conditioning isn’t working properly, the air you’re breathing could be contaminated with dust and other particles. Air conditioning maintenance in your vehicle guarantees clean, comfortable air for you and your passengers.

4. Better Fuel Economy

When temperatures rise and your car’s AC isn’t working, the sole solution is opening windows to let in cool air. However, opening the windows can increase the vehicle’s drag, causing your car to actually use more fuel. Maintaining your vehicle’s AC system helps to ensure better fuel economy.

How to Maintain Your Car’s Air Conditioner

Inspecting The A/C System & Keeping It Running

When the temperature inside your vehicle begins to climb and your air conditioner fails to kick in, you have no choice but to roll down the windows. However, if you open your windows, you may increase the drag on your automobile and waste more gas. Better gas mileage can be achieved by regular AC service.

Even if you only use your AC sometimes, you should still check it over to make sure everything is in working order. Just almost everyone can accomplish 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). Any obstructions, like a clogged bug screen, to the condenser’s airflow should be removed. A decrease in cooling efficiency is to be expected if the condenser is obstructed. Simply attaching a high-pressure nozzle to your 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. When an air conditioner is on, the radiator fan, if it is electric, must run continuously. If the fan isn’t functioning, the pressure in the system can build up to the point where the hoses burst and Freon and oil leak out. When the air conditioner is on, just one of the two electric fans (if present) needs to be operating. If you’re driving and the temperature of the air coming out of the vents is chilly but it climbs noticeably when you let the engine idle, it’s likely that the cooling fan is broken.

Mechanical clutch fans, which typically feature an internal thermostat, are designed to tighten and speed up as air is forced between the condenser and the radiator. The fan clutch’s health can be determined with a simple test. Once the engine is completely cooled down, you can reach in and manually rotate the fan. The fan’s motion should be unrestricted. 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 hot, it likely has a faulty fan clutch. According to 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.

Next, you need to visually inspect the fan belt to make sure it is in good working order. You should check the belt’s underside for any signs of cracking. When a broken belt is discovered, it must be changed immediately. 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 automobiles avoid this issue 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

We are currently performing an air conditioning system check. Turn the thermostat all the way down and the fan all the way up before starting the engine. A clutch at the front of the air conditioner compressor turns the motor within. The compressor’s clutch and drive pulley should rotate in unison if you give it a close look. Every 20-30 seconds, the clutch will engage and disengage normally. A low Freon level is indicated 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. In such a case, it is recommended that you seek the assistance of an expert. There is a recommended amount of Freon that should be present in every air conditioner. It is common practice to attach a label to the top of the radiator housing, the underside of the hood, or the evaporator compartment of an air conditioning system. This label specifies the type and quantity of Freon (in ounces and pounds) that must be present for the system to function properly. When Freon seeps out, it usually takes oil with it, so the spot where it’s leaking is easy to spot. Black or oily residue on a hose or fitting is a telltale sign of a leak. It is also possible to locate leaks with the use of a leak detecting dye or a technologically advanced leak detector.

It is not a good idea to simply add more Freon to a system that is low on the chemical. If you add too much Freon to a system, you could damage the compressor or cause the pressure in the system to rise so high that the hoses rupture. In order 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 tag. When it comes to air conditioning, a vacuum pump and a set of gauges are required for the recharging process. Due to the fact that water boils at a vacuum of 17 inches at sea level, any system subjected to a vacuum greater than this will experience dehydration. Keep the vacuum pump running for at least 20-30 minutes to get rid of any remaining moisture. A vacuum side of the low-pressure gauge lets you know just how much suction is being generated. After 20-30 minutes of purging the system, the technician flips a switch to see the low-pressure side of the vacuum gauge. They should check for leakage of vacuum in about five minutes. Generally speaking, if a system can hold vacuum, it can also hold Freon.

DIY Recharge Kits?

DIY recharge kits are available at most hardware stores, however they should be avoided. It’s important to keep in mind that a faulty air conditioner could be broken for causes other a lack of Freon. What would happen if the issue with the system wasn’t low Freon but something else? When liquid Freon enters a full system, it can destroy the compressor or cause the hoses to burst, which can lead to a catastrophic leak. No, that’s not a nice situation at all.

Working on an air conditioning system requires extreme care. If a line were to burst and Freon got in your eyes, it would instantly freeze them and could induce blindness if you didn’t have safety glasses on. Oil charge kits are also available at auto parts stores, but their use requires the expertise of a mechanic. Excess oil in the system will lower the efficiency of the machine. Oil is typically unnecessary unless parts of the system are being changed.

Is Dripping Water A Sign?

The use of an air conditioner causes water to drip from the bottom of the car. It’s usual for there to be some moisture in the cabin even after the evaporator has been disconnected. Condensation drains may be clogged if water enters the passenger side floor from above rather than below the car. When water sits for an extended period of time, fungi and mold can form, eventually clogging the drain port or the hose leading outdoors. Typically, this requires a thorough cleaning of the vehicle’s undercarriage.

The last and most frequent inquiry I receive is “why does it take so long for the air to turn cold?” There are a several factors at play here, the most obvious of which is the sun’s heat radiating off the dashboard and into the cabin. For the dashboard to cool down, please wait a few minutes. Additionally, a system performs better when humidity is reduced inside the car. The process takes a few minutes, and the drips on the car’s undercarriage are visible throughout that time. Finally, most modern cars contain a cabin air filter that, when clogged, limits the flow of air through the dashboard. This filter needs to be swapped out at least twice a year.

4 Reasons Your Car A/C May Be Blowing Hot Air | Tires Plus

Prevent waiting in line at the repair shop by having your air conditioner checked out and serviced well in advance of the summer season. Moreover, when people are uncomfortable, they are more likely to spend money than is necessary. Freon does not wear out and need to be replaced because of normal use, so be wary of stores that tell you otherwise. Recharging your air conditioner is an easy and profitable up-sell, which is why many fast lube companies recommend it. In all likelihood, they are not following the recharging technique outlined in this post and are instead just adding Freon.


Why is my Air Conditioner hot even when idle?

Some conventional vehicles have problems with hot air conditioning even when they are idling. Accidents that happen while driving.

Poor or absent vehicle maintenance is a major contributor to this issue.

What does the average Air conditioner repair cost?

The expense of repairs is system-specific. Estimate between $200 and $800 to replace the complete system.

And if your condenser fan breaks and needs replaced, you should expect to pay between $300 and $500 for the labor and parts. Because this is a common mistake, the specifics and associated expenses might range greatly.

Some other components can be replaced for less than $300. When making a purchase, you can check pricing at a variety of different locations.

Can I repair the Air Conditioner myself?

The short answer is no; this should not happen. Your air conditioner will run more smoothly if you don’t try to fix it yourself. When the air conditioner in your automobile stops working, all you have to do is take it to a skilled repair.

However, there are some components that you may inspect and clean on your own, including the air filter, thermostat, circuit breaker, and air conditioner.


If your AC stops working, and you’ve read this article, you now know what to do. The issue could originate from a number of internal AC components.

In some cases, a thorough cleaning and inspection may be in order. However, if you are unable to remedy the problem, you should have your vehicle serviced by a professional. Likewise, the cost will be based on the state of your vehicle.

Maintaining your vehicle regularly is a must. You and your loved ones will be safer if your car is in good operational condition.