Hi All. I am the new owner of a 2004 G35 6mt Sedan and I love this car!! I've had it for about 2 weeks without any issues but yesterday (one of the hottest days of the year) I started to experience an issue with the A/C. Yesterday about noon I drove the car for about 1 hour with a/c on and working and then parked it at a restaurant for about another hour. When I got back in the car and turned on the A/C (auto A/C set at 70 degrees) the air was blowing luke warm and it took about 15 minutes for the air inside the cabin to finally cool off. Made a few more stops along the way back to my office, turning the car on and off each time, and the A/C worked great each time. The A/C also worked fabulously this morning and during a quick trip this afternoon. However, upon returning back to my office this afternoon the A/C wasn't cooling off the cabin again so I parked the car and tried to figure out the problem.

I noted that the A/C compressor was only engaging for a few seconds at a time and then turning off. Every time the compressor would engage, both radiator fans would turn ON so I know they work. After the compressor cycled a few times it suddenly started again and remained on which quickly cooled the cabin and kept it cool for the remainder of my trip.

If the A/C never worked right this problem would be easy for me to diagnose but the fact that it works 90% of the time baffles me. The fans work; the compressor & relay work; the fact that the system works well at times means that the refrigerant should be charged. I suppose air conditioning / stereo control board could be going out.

I did notice one other thing today that I never noticed in the past two weeks. After the car sat in the sun during my lunch break, I noticed that the ambient air temperature reading was 119 degrees and it took about 15 minutes of driving for it to cool down to normal. So does anyone think the ambient temp sensor is bad AND IF IT IS, could this be affecting my air conditioning? I fail to see how a warm air reading from the ambient temp sensor will prevent the a/c from turning on but I've seen stranger things before. If anything a warm air reading should make the a/c work even better! If this isn't the problem then the only thing I can guess is the dreaded Bose stereo control board problem (radio/cd/cassette/satellite works perfectly FYI).

Any input will be greatly appreciated. Thanks!

 

I doubt Ambient air temp sensor would affect it. I see nothing in the FSM saying it would have an impact. I also notice on VERY hot days when the car is baking, it takes a few mines for that sensor to settle at an accurate temp.


The way these compressors work is that they are also engaged. They don't cycle on and off like other vehicles do. They have variable pistons used to control the pressure in the sustem. So when your compressor is engaging and disengaging, that would lead me to suspect you have a pressure issue.

You really need to hook a set of gauges up and read the pressures inside the system.

Page 94 has the pressure ranges, but read through the FSM as there is a trouble diagnostic routine

http://www.nicoclub.com/FSM/G35/Sedan/2004/atc.pdf

 

Check the AC belt. My AC was acting up because the belt was old and cracked.

 

Mine did the same thing. It ended up being a bad compressor.

All estimates are 1,700 or higher.

Sucks!!!