2004 G35 Sedan 150k miles.

The Air conditioning is not blowing cold air when it's hot outside. I am looking for any advice on what to fix/replace. The car has been to a local mechanic and they couldn't locate a problem.

I have checked the pressures with gauges. Everything appears to be in order there 50ish on the low side and 150ish on the high side. The compressor comes on. Both fans come on when the AC is switched on. My aftermarket JVC radio recently also died but the buttons for heat/ac seem to be working fine as it turns the compressor on when you turn it on. Also there is a very small amount of cool air coming through when it's cooler outside (maybe 5-10 degrees less than ambient air) and the heat works just fine.

I have also checked the sensor under the steering wheel and it is connected. When trying to get cold air on a hot day I have the AC temp set to 60 degrees which is as low as it goes. Have replaced the cabin air filter and have tried on fresh/recirc etc.. none of that makes a difference.

I have noticed the low pressure side ac pipe does not get cold at all. In my newer cars this pipe will get so cold you can't hardly touch it.

My next step was to see about vaccuming out the system and adding in the exact right about of freon and oil to see if that fixes it. I am just wondering if I am missing anything that may be specific to these cars.

Thanks in advance for any advice.

 

Were those pressure readings taken while the compressor is running? It can give a false reading otherwise.

 

Yeah that was with compressor running.

 

Have you consulted the FSM?

http://www.nicoclub.com/service-manu...Sedan/2004/atc

See page ATC-40

Telcoman

 

Your cabin AC fan is working correct? The system is incredibly simple, compressor needs to turn on and STAY RUNNING fan needs to be running in both the evaporation and condenser coil (radiator fan and the cabin AC fan), blend door needs to be open to cold air (controlled by user selected damper control AND the ambient air temp sensor on the dash). If the compressor is running, the radiator AC fan is running, and the cabin AC fan is running then it's pretty much down to the blend door in the ductwork to allow the air to flow past the coil, or the ambient sensor/AC controller.

Double check that you don't have a giant mouse nest or something built up at the radiator and that your AC blend controller is properly cycling between the various air ports.

AC controller and ambient sensor can be troubleshooted with the factory service manual.

 

Forgot there are two ambient sensors, one inside, one outside in the bumper. The external is easy to troubleshoot because it will show the correct outside temp if it's working.

 

The condenser is pretty clean. I replaced the radiator about 10k miles ago and cleaned it all up then. My concern is why is the low side pipe not getting cold. It's like there's something blocking the Freon from circulating. But it has good pressure. Inside the fan blows strong. Compressor stays on all the time. I'll definitely check the FSM. Thanks for posting that!

 

I might consult the temperature/pressure charts in the ATC section of the FSM. It sounds to me like the expansion valve may be buggered.

 

My a/c was intermittent for a year before my car overheated. I replaced the radiator and the problem stopped. You say you replaced the radiator 10k miles ago, so I'm not sure if that could still be the issue. Sorry