I think i might have overcharged my ac. Here is the background:

In the last few months, the ability of my ac to keep the air cold when the fan is on high diminished to the point where the air was only slightly cool, not cold. Using a recharge kit that has a gauge, I put a can of R-134a into it. This helped a lot but it didn't seem like it was back to "icy". So I got another can the following week and plugged in the recharge kit to check the gauge. According to the temperature section of the gauge, the AC was still lacking pressure. The pressure gauge also shows temperatures and has a note on it that says "point arrow to outside temperature. In this case the outside temp was about 100 degrees(which equates to 48 psi on the gauge) and the pressure of my system was at about 35 psi.

So I added the second can, which got it close to where I thought it should be(I think it got to around 45 psi). I suddenly noticed that the compressor was cycling on and off. When the compressor was on, the pressure on the gage was normal but when it shut off, the pressure spiked off the gauge. Is this pressure change normal when a compressor shuts off? For those who are wondering, I was pugged into the port that had the "L" cap on it so I'm assuming that I had to correctly plugged into the low side.

While I am driving I don't have any issues with the AC. It blows continuous ice cold air. However, when I sit at idle the AC compressor starts to cycle. Yesterday I was sitting in my car for awhile talking on my phone with the AC running and I noticed after about 10 minutes or so, the air coming out of the vents was no longer cold. It was as if the AC had turned off completely. However, when I started driving that AC returned to its normal functioning.

Did I overcharge the system or is this some other AC problem? The AC light never turned off even when the AC wasn't working. Temperatures around here are currently about 100 degrees every day.

I overcharged mine a few weeks ago. Same scenario you had. One can didn't seem like enough, but two was too much. Didn't know at the time the whole system only holds 20 ounces of freon. For the fix, I just removed the can of coolant from the trigger contraption, hooked up the tube to the A/C system connector, and squeezed the trigger, discharging the extra coolant, until a proper PSI was reached. Hope this helps.

You should try to never release refrigerant into the atmosphere. It's not a good practice.

I know. Thanks for the reminder.

That trigered ice cap on north pole to meltdown. Danm you, SMEE for killing the Earth. JK

And now we're in the middle of a heat wave.....thanks.

did the same thing.... thought I'd boost the A/C efficiency, but apparently these take less pressure than the can recommends. WOOPS! Had the same symptoms: compressor would cycle on and off every 5-10 secs while at idle or low speed, but while cruising it was ok.

I just bled out the extra refrigerant and it seems to be okay now... hopefully no lasting damage.

I am wondering if you experienced any problems doing this as I just had to do the same today. Compressor stop cycling and temp in car was nice down to about 45 - 48 degrees so I think all is well but just wondering if you experience problems.

Never seemed to notice any significant problems, so seems like it was a temporary issue. Once the pressure was back down to nominal, was working just fine.

not trying to grave dig too deep here but from my understanding the compressor cycling on and off is a good sign at idle. the system is running efficiently to the point of not needing it to run continuously.

However I am having an issue myself. I added some to my 08 and its now warmer at idle than it is at ~1500rpm. My expansion valve is also staying open after the add. Im pretty sure the answer is to release some but just wanted to check in and see if any of you have an update on your issues.

I had very similar experiences and I thought the same thing, until I sat in the cab and noticed the air was not cold. I vented some (sorry ozone) and we are good.