What Are the Reasons for Normal AC Pressure But No Cooling?
3 Answers
Reasons why a car's AC has normal pressure but does not cool: 1. Lack of refrigerant: Car AC systems typically require refrigerant replenishment every 2~3 years. 2. Damaged air blend door: The blend door motor, usually located in the lower middle part of the dashboard, acts as the main switch for AC vents. Even if the AC can cool, cold air may only seep through gaps, failing to achieve proper cooling. If no air comes out from any vents when the AC is turned on, the blend door motor needs replacement, which requires dashboard removal. 3. Dirty condenser: Cleaning the radiator and condenser primarily aims to improve heat dissipation. 4. Faulty AC compressor, throttle valve, or expansion valve: Malfunctions in the expansion valve or throttle valve directly lead to poor AC performance. 5. Worn or loose belt: During operation, slipping may occur, causing belt breakage, unusual noises, loss of power assistance, and poor AC performance.
I often deal with such air conditioning issues—normal pressure but no cooling is quite common. A faulty compressor is the key reason; if the clutch slips or fails to engage, the compressor won't work, and no amount of refrigerant will help. Another issue is a stuck or clogged expansion valve, which prevents refrigerant circulation and cooling. Fan failure is also frequent—if the cooling fan doesn't spin, heat builds up in the condenser, causing the system to fail. A malfunctioning thermostat switch can misread temperatures and prevent the AC from starting. Electrical problems like blown fuses or damaged relays can cut power to the compressor. Once, I fixed a car where leaves jammed the fan—clearing them solved the problem immediately. Regular maintenance is crucial: replacing filters and cleaning the condenser annually can prevent these headaches. If the AC stops while driving, don’t push it—get it checked right away for safety.
My car had the same issue last year. The AC pressure gauge showed normal readings but it was blowing hot air, which was unbearable. After inspection, it turned out the cooling fan was broken—the fan motor was burnt out and wouldn't spin, so the heat couldn’t dissipate. Another possible cause was a dirty AC filter blocking airflow, which reduced cooling efficiency. I ignored replacing it and paid the price. The compressor not engaging could also be the culprit—loose wiring connections or a blown fuse might cause it to shut down. A stuck expansion valve can make the high-pressure pipe scorching hot. I learned my lesson and now always ask the mechanic to check the fan and electrical circuits during maintenance. I’d advise regular car owners not to overlook small warning signs, like unusual fan noises or delayed AC startup—they’re red flags. Regularly cleaning the condenser and replacing the filter is cost-effective and highly effective.
