Turning on AC or Heater caused idle to drop severely

[kailuakeith]

My car is a 2003 Honda Accord. My kids drove it but have moved out and have lives elsewhere now. I charged the AC with R134 a few months ago and it got cold just fine. But, the idle was fluctuating wildly even without the AC on, so I ordered an IAC valve. I came back from a trip and some other chores and finally replaced the IAC valve and now it idles just beautifully. BUT, when I turned on the AC, it got cold but the idle dropped so low it seemed like it would die. So I gunned it a little to get the idle up. I thought it needed to be run after sitting for several months, so went for a ride, and turned the AC on only after I was moving at 30mph or so. Very quickly the rpms dropped like it would die and I could hear gas venting under the hood. I turned the AC off and the car ran fine. I think the venting sound was the refrigerant.
I am not sure that maybe this is the compressor seizing up?
Or, from what I read here, could it be that before I recharged it, all the refrigerant leaked out and air got into it? I did not have it vacuumed out. It had been charged by a shop 5 years ago and it last that long so I thought it would be no problem to charge it myself this time. If air got in the line and now mixed with the R134, could that cause the idle to drop to the point where the engine might die when I engage the AC?
The same extreme low idle occurred when I turned the heater on instead of the AC. How could that be happening? That shouldn't affect the compressor or the R134 and any air in the lines, correct?
Thanks for your help

[kailuakeith]

So, I will try to be clearer. I paid a shop to charge the AC about 6 years ago. It worked fine until 2 years ago and slowly stopped getting cold. I went back to get another charged but the shop ran out of refrigerant in the middle and sent me away without any cost. (Probably not the most reputable shop but they were less expensive when I called around.) Then, I was out of state taking care of declining parents for a long time and my son drove the car without AC, or maybe he turned it on occasionally but it would just barely put out any cold.

Could this long period of 2 years without adequate refrigerant allow regular air into the lines?

Then, my brother and I bought R134 and recharged it about 3 months ago. It wasn't driven afterwards until I replaced the IAC valve. Now I drive it and even though the idle is smooth without the AC on, the second I turn on there is a vibration. I cannot see where it comes from. The AC clutch works and I see the compressor spin and the AC gets cold.

I have read that if there is air in the lines, that means less R134 can fit in, and that means there is less oil (which comes in the R134?) to lubricate the compressor. I have read that means this increases the risk of the compressor burning out. Is any of this true? I am not sure my understanding is correct.

I can't figure out what else could be causing the vibration. The only time it went away was after I took it out on the highway but it could be because the AC had gotten cool enough that the compressor was cycling off and that is when I noticed it was smoother and without vibration.

Oh, I did not replace the dryer unit. Is that a fatal flaw? I am an AC newbie.

[Cusser]

Vibration could be due to a loose compressor mount too.

Yes, from your story yours needs to have the leak fixed (don't use ANY sealer), a new drier, then have the system evacuated, and the correct amount of refrigerant added. Yes, special equipment is needed. Otherwise you're just doing a band-aid.

Yes, the shop can also diagnose the vibration. Sorry, sometimes we all need to visit a shop....a real AC shop in your case, not a Brake-O with a sign....

[kailuakeith]

I am in the boondocks so there are only a few places that do AC and they are like the one that ran out of R134a. I will look in a bigger town. Thank you for your reply by the way.
Meanwhile, my leak must be really slow because the R134a has not discharged in the 4 months since I recharged it, at least not completely. Is there a thread on how they would go about finding the leak? Thanks again.