Car A/C Not Working? Common Causes and Solutions
Is your car's air conditioning blowing warm air? Learn the most common reasons your A/C fails and what repairs typically cost.
Nothing Worse Than a Hot Car With No A/C
When your car's air conditioning stops working during a NYC summer, it's more than uncomfortable—it can be dangerous. Understanding why your A/C fails can help you get it fixed faster and avoid costly mistakes.
How Your Car's A/C Works
Your A/C system circulates refrigerant that absorbs heat from the cabin air. Key components include:
- Compressor: Compresses and circulates refrigerant
- Condenser: Releases heat to outside air
- Evaporator: Absorbs heat from cabin air
- Expansion valve: Controls refrigerant flow
- Refrigerant: The medium that carries heat
Common A/C Problems and Solutions
1. Low Refrigerant
The most common cause of weak or warm A/C.
Causes:
- Small leak in the system
- Degraded seals over time
- Accident damage
Symptoms:
- A/C blows cool but not cold
- A/C works intermittently
- System eventually blows warm air only
Solution: Locate and repair the leak, then recharge the system. Simple recharge: $100-$200. With leak repair: $200-$500+.
2. Refrigerant Leak
A/C systems are sealed—if refrigerant is low, it's leaking somewhere.
Common leak points:
- Hose connections
- Compressor shaft seal
- Condenser (often damaged by road debris)
- Evaporator
Solution: UV dye test to locate, then repair. Costs vary widely by leak location.
3. Compressor Failure
The compressor is the heart of your A/C system. When it fails, the system doesn't work at all.
Signs:
- A/C doesn't engage (no click)
- Grinding noise when A/C is on
- A/C clutch doesn't engage
Solution: Compressor replacement: $500-$1,200+
4. Electrical Issues
The A/C system has multiple electrical components that can fail.
Possible culprits:
- Blown fuse
- Bad relay
- Faulty compressor clutch
- Pressure switch failure
- Wiring problems
Solution: Diagnosis and repair: $100-$400 typically
5. Condenser Problems
The condenser sits in front of your radiator and can be damaged or blocked.
Issues:
- Blocked by debris (leaves, bugs)
- Damaged by road debris
- Internal blockage
Solution: Cleaning may help. Replacement if damaged: $300-$700
6. Clogged Expansion Valve
If the expansion valve is stuck or clogged, refrigerant can't flow properly.
Symptoms:
- Insufficient cooling
- Frost on components (too cold in one area)
- Erratic cooling
Solution: Replacement: $150-$350
7. Blend Door Problems
The blend door controls whether air flows through the heater or A/C. If it's stuck, you might get hot air even with A/C on.
Signs: Clicking sounds from dash, temperature doesn't change
Solution: Actuator or blend door repair: $150-$500
What NOT to Do
- Don't just add refrigerant repeatedly - You're wasting money and harming the environment if there's a leak
- Don't use stop-leak products - They can clog your system and cause bigger problems
- Don't ignore warning signs - Small problems become big problems
A/C System Maintenance
- Run your A/C year-round (monthly in winter) to keep seals lubricated
- Have the system checked annually
- Replace cabin air filter regularly
- Address weak cooling early
DIY vs. Professional A/C Repair
DIY-friendly:
- Checking fuses
- Replacing cabin air filter
- Basic recharge (if you know what you're doing)
Needs professional:
- Leak detection and repair
- Compressor replacement
- Electrical diagnosis
- Refrigerant recovery
Mobile A/C Service in NYC
NYC Mobile Auto Assist offers A/C diagnostics and many repairs at your location. We can check refrigerant levels, identify leaks, and perform most repairs without a shop visit.
Stay cool this summer—call us for A/C service.
Need Professional Help?
NYC Mobile Auto Assist provides expert mobile mechanic services throughout all five boroughs. We come to you!