Strange Vibration when 740 is at complete STOP!

Hi I tried searching for some news on my problem but im not getting any answers. I have a 1988 Volvo 740 GLE, the car is running great, but it seems when my air conditioning comes on in my car, there is a device in the engine that turns on and vibrates for a flash second every 5 or 10 seconds, and makes sort of a click sound. YOu can only feel these vibrations when the car is at a stop (like a Red Light). When I'm driving I can still hear that click sound. I really need to know what my problem is. And even when I try to turn off my air conditioning it somehow does not completely turn off, it still comes out of the vents lightly.

the clicking sounds like the compressor clutch activating, you may have a dodgey relay or more likely, the sensor is buggered in the...thiingy.. lol forgot the name. its that big round thing with a couple of pipes on it, there a 2 wire sensor, it could be that which is playing up. how long can you drive before this clicking happens? also check the ac unit is tight and belt in good order and at the right tention

yeah it sounds like an activation sound and then it just stops and it repeats...and the whole car vibrates. ummm when Im driving and if i open the window and listen it does the clicking/activation noise in a pattern similar to when the car is at a complete stop...but as I said when Im driving there is no vibration....how can i close off the AC so it stops coming out?thanks

if the button isn't turning the ac off, your controlunit could be fauty. if you want to stop the ac totally, then disconect that sensor i mentioned. tha will stop it. i am starting to think your compressor might be a fault. you say its doing it when stoped? i don't think your supposed to have the AC on at idle, could be wrong tho.

when i meen stop i meen that car is still running....i just have my foot on the brake....were is this sensor that i must remove I will do it as soon as possible...i think my air conditioning has a leak in it anyway so i might as well

yup so i unplugged it and your rite it stopped...so what can i do to fix the sensor

It could just be that the system is out of gas....

To completely shut off que AC, the command lever must be out of both: "blue star" or "front wondshield vent". Simply turning off the fan doesn't make it. My 1987 AC keeps running at slow first speed fan...

If you no longer require the AC system, remove the drive belt from the compressor, and pull the electrical connection either from the silver canister or the compressor. If the AC is out of gas, it's also out of lubrication so allowing it to run will just damage the compressor.