I have an 88 240 DL that I bought several weeks ago and while it is in great condition I wanted to give it a through checkup and also to convert the A/C to r134 since it was on low charge of r12.

The first strange thing is the A/C. It had just enough charge to cycle the compressor. I evaced the R12 then added an oil charge and about 8 oz of r134 to turn on the low pressure switch. So, I start the engine to begin suctioning in the remaining r134 and the compressor clutch will not engage????

I jumpered across the low pressure switch to make sure it wasnt stuck and that did nothing.I checked the fuse and it was fine. I have not had a chance yet to perform other tests of the electrics and I am while I understand A/C systems, this is my first Volvo to work on. I am looking for suggestions on where to start checking. Is there a relay inside the car that I am not aware of? Your help on this would be appreciated as I have run out of time for a while till I can check the circuits.

My second problem is the light surge in idle. I thought I would test the idle circuits and ran into an interesting situation. It is cycling in its idle every 2 to 3 seconds from 700 to 775. I went to set the base idle, but when I grounded out the IAC the engine died! I think I may have found the problem since it seems to be the IAC is carrying the whole burden of idle air and must be operating near its max. I am wondering why it was set this way? Is it possible for there to be a problem with the idle air adjuster screw? Also, which way do you turn the screw to increase idle speed? Since the engine dies when the IAC is grounded I havent been able to determine the right direction to turn it.

The car is showing no signs of poor running at present. I am getting 24mpg average city/highway, but it isnt set right and I want to correct it.