Air Conditioning Not Cold: 5 Problems and Solutions [2025 Guide]

On a hot summer day, there's little more frustrating than an air conditioner that no longer blows cold air. While the outside temperature rises to 30 degrees Celsius or more, your AC only blows lukewarm or even warm air. Properly functioning car air conditioning isn't just about comfort—it also contributes to safety by reducing fatigue and preventing windows from fogging up. In this comprehensive guide for 2025, you'll discover the five most common reasons why your AC no longer blows cold air, the solutions, and the cost of repairs.

How Does a Car Air Conditioner Work?

To understand what can go wrong, it's helpful to understand how an air conditioner works. The system consists of a compressor that compresses refrigerant, a condenser that removes heat, an expansion valve that reduces pressure, and an evaporator that cools the cabin. The refrigerant circulates through this closed system, absorbing heat from the cabin.

Problem 1: Not Enough Refrigerant (Most Common)

This is by far the most common cause – approximately 60-70 percent of all air conditioning problems. Symptoms include gradually less cold air over months, air conditioning initially working at high speed but not at idle, and sometimes visible ice formation on the pipes.

Causes: Natural leakage through microscopic pores in hoses and connections (normally 5-10 percent loss per year), leaks at hoses or connections, defective seals, or damage to the condenser from stone chips.

Solution: At Faay Auto Groep, we offer air conditioning service including leak testing, evacuating old refrigerant, vacuuming the system, and topping up with new refrigerant and compressor oil. Costs: €80-€150 for a standard top-up. In case of a leak, repairing it first costs €150-€400, depending on the location.

Please note: Topping up without a leak test is a waste of money if there is a leak.

Problem 2: Faulty Air Conditioning Compressor

The compressor is the heart of the air conditioning system and circulates the refrigerant. Symptoms include no cold air despite the correct refrigerant level, unusual noises (squeaking, grinding, or clicking) when the air conditioning is turned on, and a compressor clutch that doesn't turn when the air conditioning is running.

Causes: Wear and tear due to age or high use, internal damage from driving too long without refrigerant, lack of lubrication, or electrical problems (clutch or relay).

Solution: Replacing the compressor costs €400-€900, including labor and new refrigerant. If the problem is electrical, replacing the clutch or relay alone costs €100-€250.

Prevention: Use the air conditioning at least once a month, even in winter, for 10 minutes to keep the system lubricated.

Problem 3: Clogged or Faulty Condenser

The condenser is located in front of the radiator and cools the warm refrigerant. Symptoms include poor air conditioning at low revs or when stationary, but improved while driving, less effective air conditioning in warm weather, and no cooling in traffic jams or at stoplights.

Causes: Clogged by dirt, leaves or insects, damaged by stone chips or accidents, or internal corrosion and blockage.

Solution: Cleaning the condenser costs €40-80. Replacing the condenser costs €300-600, including a new dry filter and refrigerant.

Problem 4: Electrical Problems

Various electrical components can fail. Symptoms include the air conditioner not turning on (no sound, no change), the fan blowing but no cooling, or the air conditioner turning on and off without a pattern.

Possible causes: Pressure switch that protects the system is defective, thermostat or temperature sensor is defective, relay or fuse is defective, or there is a wiring problem.

Problem 5: Cabin Filter Clogged

A clogged pollen filter restricts airflow. Symptoms include weak airflow from vents, cold air but low volume, and a musty or unpleasant odor from the air conditioner.

Solution: Replacing the pollen filter costs €30-70, including labor. This is typically done during a major service.

Air Conditioning Maintenance Tips

Regular use: Use the air conditioning system at least once a month, even in winter, to keep the system lubricated. This prevents seals from drying out.

Annual service: Have your air conditioning serviced every two years. This includes pressure testing, leak testing, and topping up if necessary. Costs of €80-€120 can prevent hundreds of euros in repairs.

Replacing the pollen filter: Replace the cabin filter every year or every 15,000 km. A clogged filter puts strain on the system and reduces its effectiveness.

Don't leave repairs undone: Small leaks become larger leaks. A compressor running without refrigerant will eventually break down.

Frequently Asked Questions

How often should I top up the air conditioning?

A properly functioning air conditioning system generally never needs to be topped up – it's a closed system. In practice, every system loses 5-10 percent of its refrigerant annually through microscopic pores. It's recommended to have it serviced every 2-3 years, checking and, if necessary, topping up. If you need to top up more often than every 2 years, there's a leak that needs to be repaired. Simply topping up without a leak test is a waste of money.

Can I top up refrigerant myself?

This is strongly discouraged. Since 2017, it has been illegal for private individuals to purchase fluorinated greenhouse gases (F-gases) such as R134a or R1234yf refrigerants without certification. Furthermore, proper refilling requires professional equipment to evacuate the system and add the correct amount of refrigerant. Too much refrigerant is just as bad as too little. DIY air conditioning recharge kits sold online are often ineffective and can cause damage. Leave air conditioning service to professionals.

Why does my air conditioner smell musty?

A musty smell is caused by mold and bacteria growing on the evaporator. Moisture condenses on the cold evaporator, and if the car is frequently driven short distances, it doesn't dry properly. Solution: replace the cabin filter (€30-70), have the evaporator cleaned with an antibacterial agent (€40-80), and preventatively: turn off the air conditioning 2-3 minutes before arriving but run the fan to dry the evaporator. A clean evaporator and new pollen filter usually eliminate the smell.

Does the air conditioning use a lot of fuel?

Yes, the air conditioning compressor is driven by the engine and requires power. The increase in consumption is approximately 0.3-0.8 liters per 100 km during normal use, which represents an increase of 5-15 percent. At high outside temperatures and with maximum cooling, this can increase to 1.5 liters per 100 km. However, at speeds above 60-70 km/h, having open windows is just as bad or worse due to increased air resistance. Conclusion: use air conditioning when necessary for comfort and safety – the additional costs are minimal and outweigh the benefits.

What is the difference between R134a and R1234yf refrigerants?

R134a was the standard refrigerant from 1990 to 2017. R1234yf is the new, more environmentally friendly refrigerant required in new cars from 2017 onwards. The main difference is the impact on global warming: R1234yf has a GWP of 4 versus 1430 for R134a. They are not interchangeable – each system is designed for a specific refrigerant. R1234yf is more expensive (€60-80 per kg vs. €20-30 for R134a). Check which type your car uses – it's listed on a sticker in the engine compartment.

Can I use the air conditioning in winter?

Yes, and it's even recommended. Benefits of air conditioning in winter: it prevents windows from fogging more effectively by removing moisture from the air, keeps the air conditioning system lubricated, prevents seals from drying out, and can be combined with heating for dry, warm air. Use the air conditioning at least once a month for 10 minutes, even in freezing weather. The compressor only runs when the outside temperature is above approximately 5 degrees Celsius (thermal protection).

Conclusion: Maintenance Prevents Expensive Repairs

An air conditioner that no longer blows cold usually has a relatively simple cause: insufficient refrigerant, a faulty compressor, a clogged condenser, electrical problems, or a clogged filter. Most problems are preventable with regular use and periodic maintenance. An air conditioner service every two years costs €80-120 but can prevent costly repairs costing €400-900.

Don't wait until the middle of summer to have your air conditioning checked. Test everything in the spring to make sure it's working properly and schedule service if necessary. This prevents you from being stuck in the heat without cooling and potentially having to wait weeks for an appointment.

Air conditioning no longer blowing cold? Schedule an appointment now with Faay Auto Groep for air conditioning diagnostics and service. We'll inspect the entire system, perform leak tests, and repair any issues using high-quality parts. Our air conditioning service, starting at €95, includes inspection, refills, and advice. Call 030 601 99 15 or book online. We're ready to assist you in Nieuwegein!