No AC in extreme heat can cause driver fatigue and health risks. If you must drive, stay hydrated, crack windows for ventilation, and take frequent breaks.
AC Not Working? Beat the Heat Today
When your car's AC stops working, every drive becomes uncomfortable and even dangerous. Foggy windows reduce visibility, heat exhaustion risks increase, and passenger comfort disappears. Whether it's a simple recharge or major component failure, AC problems only worsen with time. Driving without AC in summer heat isn't just uncomfortable - it's a safety issue. Our certified technicians have the specialized equipment and expertise to diagnose your AC problem quickly and get you back to cool, comfortable driving.
Warning Symptoms to Watch For
AC blowing warm air
MediumMost common AC complaint. Usually indicates low refrigerant from leak, compressor not engaging, or blend door issues.
No air from vents
HighBlower motor failure, resistor problems, or electrical issues. Affects both AC and heating system.
AC works intermittently
MediumCompressor cycling issues, low refrigerant, or electrical problems. Often indicates imminent complete failure.
Weak airflow from vents
LowClogged cabin filter, evaporator freezing, or blend door problems restricting airflow.
Strange smell from AC
LowMusty odor indicates mold/mildew in evaporator. Sweet smell could be coolant leak into cabin.
AC making noise
HighSquealing, grinding, or rattling from compressor or blower motor indicates mechanical failure.
Water inside vehicle
MediumClogged evaporator drain causing water backup into cabin. Can damage interior and electrical.
AC only cold when driving
MediumCondenser fan failure or low refrigerant. System can't maintain cooling at idle.
Fog on windshield when AC on
LowEvaporator core leak allowing refrigerant into cabin, or excessive moisture in system.
AC clutch not engaging
HighVisible sign compressor isn't working. Could be electrical, low refrigerant, or compressor failure.
Important: If you experience any Critical or High severity symptoms, stop driving immediately and contact us for emergency service.
Common Causes & Issues
Refrigerant Leak
Very CommonMost AC problems start with slow refrigerant loss through seals, hoses, or components. System can't cool properly without correct refrigerant level. Leaks worsen over time and must be found and repaired, not just recharged.
Compressor Failure
CommonAC compressor is the heart of the system. Internal wear, clutch failure, or seized bearings stop refrigerant circulation. Running low on refrigerant damages compressor. Most expensive AC component to replace.
Electrical Problems
CommonBlown fuses, bad relays, faulty pressure switches, or wiring issues prevent system operation. Modern AC systems have multiple sensors and switches that must all work for AC to engage.
Clogged Cabin Air Filter
Very CommonDirty filter restricts airflow through vents. Simple, inexpensive fix that's often overlooked. Should be replaced annually or every 12,000 miles. Can cause evaporator to freeze if severely clogged.
Condenser Problems
CommonCondenser in front of radiator can be damaged by road debris or clogged with bugs/leaves. Can't dissipate heat properly, reducing cooling capacity. Bent fins restrict airflow.
Evaporator Issues
UncommonEvaporator core leak requires dashboard removal to repair. Can freeze up from low refrigerant or airflow issues. Mold/mildew growth causes odors.
Blower Motor Failure
CommonMotor that pushes air through vents can fail from wear or resistor problems. Affects all climate control, not just AC. May work on some speeds but not others.
Expansion Valve/Orifice Tube
UncommonControls refrigerant flow into evaporator. Can stick open (poor cooling) or closed (no cooling). Contamination from compressor failure often clogs these components.
Blend Door Actuator
UncommonControls temperature by mixing hot and cold air. Stuck doors prevent cold air from reaching vents even though AC is working. Common in vehicles with dual-zone climate control.
Our Diagnostic Process
Visual Inspection and Initial Test
Check if AC compressor clutch engages when AC turned on. Inspect belt condition and tension. Look for obvious damage to condenser. Check cabin air filter condition. Verify blower motor operation on all speeds.
Pressure Testing
Connect AC manifold gauges to check high and low side pressures. Compare to specifications to determine if system is low on refrigerant, overcharged, or has mechanical issue. Pressures tell the story of what's wrong.
Leak Detection
If low on refrigerant, find the leak source. Use electronic leak detector for small leaks. Add UV dye and use black light for hard-to-find leaks. Check all connections, hoses, seals, and components.
Electrical System Check
Test compressor clutch operation and resistance. Check all fuses and relays. Verify pressure switches and sensors working. Test blower motor resistor and controls. Scan for AC-related trouble codes.
Component Testing
Test compressor clutch engagement and cycling. Check condenser fan operation. Verify expansion valve or orifice tube function. Test blend door actuator movement. Measure vent temperatures.
System Performance Test
After repairs, evacuate system to remove air and moisture. Recharge with exact amount of refrigerant. Test cooling performance at idle and driving speeds. Verify proper pressures and vent temperatures (should be 38-45°F).
Repair Options & Solutions
AC Recharge Service
Evacuate and recharge system with correct refrigerant amount. Includes leak check and performance test.
Leak Repair
Find and repair refrigerant leak. Price depends on leak location and accessibility.
Compressor Replacement
Replace failed compressor, receiver/dryer, and recharge system. Most extensive AC repair.
Condenser Replacement
Replace damaged or leaking condenser. Common after front-end collision or road debris damage.
Cabin Air Filter
Replace clogged filter to restore airflow. Should be done annually.
Blower Motor Replacement
Replace failed blower motor or resistor. Restores air flow on all speeds.
Evaporator Service
Replace leaking evaporator core. Requires dashboard removal in most vehicles.
AC System Flush
Remove contamination after compressor failure. Prevents damage to new components.
Diagnostic Cost Comparison
| Provider | Average Cost | Turnaround | Warranty |
|---|---|---|---|
| Rohnert Park TransmissionBest Value | Affordable AC inspection | Same day service | 24 months/24,000 miles |
| Dealership | Premium pricing | By appointment | 12 months/12,000 miles |
| Chain AC Shop | Variable pricing | First come, first served | 12 months/12,000 miles |
| Mobile Mechanic | Service call fees apply | Limited AC repairs | Varies |
Save Money: We offer competitive diagnostic rates and apply the fee toward any repairs performed.
Prevention & Maintenance Tips
Run AC monthly year-round
Frequency: Once per month minimum
Potential Savings: Keeps seals lubricated, prevents costly repairs
Replace cabin air filter
Frequency: Every 12,000 miles
Potential Savings: Maintains airflow, prevents evaporator damage
Check AC performance in spring
Frequency: Before summer heat
Potential Savings: Early detection of problems saves on repairs
Clean condenser fins
Frequency: Twice yearly
Potential Savings: Maintains cooling efficiency, extends compressor life
Address small leaks quickly
Frequency: When detected
Potential Savings: Prevents expensive compressor damage
Use AC on recirculate in traffic
Frequency: In heavy traffic/pollution
Potential Savings: Reduces system strain and filter clogging
Frequently Asked Questions
Why does my AC work fine then suddenly blow warm?
This typically indicates the system is low on refrigerant and the compressor is cycling off to protect itself. Could also be evaporator freezing from low refrigerant or restricted airflow. The intermittent nature often precedes complete failure.
Can I just add refrigerant myself?
DIY recharge cans are temporary fixes at best and can damage your system at worst. Without finding and fixing the leak, you'll lose refrigerant again. Overcharging damages the compressor. Professional service includes leak detection and proper charging.
Why is AC repair so expensive?
AC systems are complex with expensive components. Labor is intensive due to system location. EPA regulations require special equipment and refrigerant handling. However, early diagnosis and repair prevents more costly component failures.
How often should AC be serviced?
Annual AC inspection before summer is recommended. Change cabin air filter yearly. System should be serviced if cooling diminishes or strange smells develop. Regular use year-round actually helps maintain the system.
Why does my AC smell musty?
Moisture on the evaporator creates ideal conditions for mold and bacteria growth. This is common in humid climates. We can clean and treat the evaporator to eliminate odors and improve air quality.
Is it worth fixing AC in an older car?
Consider repair cost versus vehicle value and your comfort needs. A working AC system adds resale value and makes driving more comfortable and safe (no foggy windows). We provide honest assessments of whether repair makes financial sense.
Get Your Vehicle Diagnosed Today
Don't wait until it's too late. Our expert technicians can diagnose and fix your vehicle issues quickly and affordably.
Same-day appointments available • Free estimates • All makes and models