Volvo: 90 volvo wont run, volvo volvo, vacuum line

Question
I have a 90 740 gl.  I took it to a local station because the air was not working.  Drove fine when I went in there but now is runs very rough.  Almost dies when you start out.  The check engine light came on as well.  They put R in the system but the compressor does not turn on at all.  I found a small white (I think) vacuum line that runs from a small unit up by the wheel well on the drivers side and the white plastic hose is just sitting lose under the manifold.  Could this line make the car now want to run?  As for the air compressor, they say it was working but that the switch on the dash was loose.  I don't buy that.  Any suggestions??

Thanks for your response!

Answer
Dan,
Hard to say what is going on with your car, but I can say that you need a shop that know the Volvo. Volvo shops know the likely things that happen and what to look for.
Why it will not run/idle, maybe that small vac line but that will need to be looked at and then see what is missing and or what was left loose that is causing that problem.
I can say that I have seen many A/C control heads go out and that is the cause of the compressor not coming on. Sorry there is not a short answer, but the car needs to be looked at and inspected to see the problems.