Hey guys,

So the A/C on my 2008 Evo X started to act funny. First time I noticed it was in dead heat of summer here in AZ. I was driving and felt the A/C turn on and off on its own. After I got home I checked it the next day and it seemed to function ok.

A few weeks later I started to notice that the A/C was weak at idle and became stronger and cooler as I drove around and put some load on the engine. At first I thought it was fine but it started to get real weak. I noticed that if I was at a stop I can rev the engine to 1500rpm and it would become cooler.

Anyway I thought to myself that my A/C might just need a slight refill. So I proceeded to buy a refill can with a gauge. I attached the gauge and it red that I was actually over at 70psi in the red area. (This reading was done according to the refill instructions of turning on the car leaving it at idle with the A/C set to maximum.) So needless to say i depressed the pin to get it to the 55psi yellow area on the gauge. This seemed to work a little bit as the a/c would blow fairly cold air while at idle on the maximum setting. (Better than previous.)

Now my question is, when I drive the car around, periodically I hear a hissing sound that seems to be coming from the front area to the right side where the A/C assembly is at. it's a slight hissing/whooshing noise it lasts about 2-4 seconds and while this noise is happening the A/C blows really nice cold air.

I was just wondering if this noise is normal? Also should I reduce the amount of the refrigerant further to the 45psi range which is labeled as blue and full? Does anyone have a specific number of the stock PSI that the A/C should be at while at full blast at idle?

Thanks for any help that anyone can give.

 

What many people don't know is that impurities in an air-conditioning system will cause it to run high in pressure, not low. You may need to have your system drained (to vacuum), checked for leaks, and refilled from scratch. But don't pay for this until more diagnostic work is done. My main point is that high pressure can mean water or air in the system.