My AC start acting up in the last 2 days. 2 days ago i start the car in the morning and the AC worked with no problem. Stopped at Costco for shopping and when i return it was 100 degrees outside and AC was blowing hot air.

I figured it’s running low on Freon so I charged it the next day in the morning with AC Pro. I added ½ can to get it to the correct charge. Drove it for a couple minutes and the AC stopped.

It seems that the problem occur after the car is warmed up. Car temp is normal 194-200F. Sometimes the AC works ok and sometimes it kicks in and stop immediately. I replaced the belts 30k miles ago. The belts have cracks but it doesn’t squeal. Any idea what’s the cause?

 

Do you have A/C gauges? Can you verify the pressures are correct?

Here's the FSM

http://www.nicoclub.com/FSM/G35/Sedan/2003/atc.pdf

 

I only have the gauge that came with the AC Pro charging kit. It shows the pressure for the low side that was a little low. I added more Freon but not all the way to the recommended because I didn’t want to overfill. I was planning to add more but after my short drive the compressor was not staying engage. I’ll check the pressure today and let you know.

 

Low side is 37-38 and ambient temp is 78.

I tried to add a little more to bring it to 40 and the compressor stoped. I turn the ac off and back on and it click and stopped. I let the car sit for several minutes and the ac worked fine.

 

What parts did you replace of the AC and who did it? Sounds like maybe the clutch isn't gapped correctly? This happened on my Volvo, I gave my sister it worked when it was cool outside or for a few minutes and then would turn off.

Buy a feeler gauge and check the gap according to the FSM. You might need a new clutch or find some ghetto fixes. I fixed the Volvo with some zip ties and pieces of a RockAuto.com magnet, lol.

 

No work was done, that's the original ac.

 

Oh, I thought it said in your post you replaced the AC 30K miles ago. Next time the AC kicks off while you have the car on. Take a broom and press the outside clutch of the compressor (careful of the belts). If it kicks on again then your clutch needs to be reshimmed, replaced, or like I did with the Volvo find a way to make the gap smaller.

 

Sorry I missed typed AC instead of belts.

The engine rpm drops when the compressor stops. Wil that occur when you have clutch problem?

 

Those DIY A/C recharge kits are dangerous. They only provide one gauge and without knowing the proper pressure you can easily overcharge and damage the system considering the green "full charge" zone on the gauge can be above the recommended pressure range of some cars. For A/C recharging you should really buy the bare simple cans, and invest in a set of hoses with high and low pressure readings.

I think you are overcharged, but not by much.


FSM page 109

At Ambient temp 77 degrees F:

High side pressure: 146-179 PSI
Low side pressure 28-35 PSI



You really need a set of gauges that has both readings to know what's going on. Read through the troubleshooting from page 110 on, but you need a high pressure gauge as well for this.

This may be a possibility, but for the high side to spike up that high, would suggest a blockage somewhere in the system

From page 20 of the FSM

The compressor on these cars runs continuously, and uses variable displacement pistons inside to prevent freeze up, so it doesn't cycle on and off like other cars. So if the compressor disengages, there is a reason. A lot of times it's pressure related.


A/C troubleshooting can get pretty complicated.

 

Blockage somewhere make sense since the compressor runs ok when it’s colder outside and the pressure in the system is lower.

What’s the solution for blockage?

 

It's usually in the orifice tube, which causes a huge differential pressure drop leading to a high high side pressure and low (or normal) low side pressure.

You really need to hook up a set of gauges that has high side and low side readings to confirm. That will tell you if you have a blockage causing a pressure problem. Anyone you know have a set to borrow?

 

I'll check if someone have gauges i can borrow at my local motorcycle club. I will let you know the reading once I get them.

Thanks for your help so far!

 

Update: Dealer had a free AC check special, perfect timing 
The dealer said AC is perfect and they were not able to duplicate my problem. Only recommendation is to change the AC belt since its cracked and maybe be slipping causing the compressor to stop.

 

AC fixed. I replace the old and cracked AC belt based on the dealer recommendation.