fan dont come on when a/c is on!

Have you double checked the pressure when its running?

 

What they said about the oil is correct, Is you're eng fan working normally is the air getting to it for it to come on, without it the Ac is going to keep cycling on the high Hd pressure Switch.

 

You need some serious electrical diagnostics on that truck for the ac u can see and try to replace the ac module if not done so already most of the time they go bad and have all kinds of weird issues if that does not take care of the issue then u need to check the wiring connections or the module and make sure it has a good ground the easiest thing you can do is look at the white on the module connection that is the ground wire jump that to a known good ground and see what happens if These two things don't help then you want to check the thermostat or freeze switch in the cab whichever it has its in the evaporator so u have to remove blower motor to get to it and of that is not the issue that what I want to do is take it to a shop that's good with volvo ac because u got a serious electrical issue and without proper diagnostic chart and schematics you won't be able to figure it out I hope some of this helped let me know if you need anything else

 

Does the ac work at a fast idle?

I have a truck that does the same thing and you have to get the idle up if you are sitting in order for the ac to work

 

Dont you have the A/C diagnostic unit on the firewall left if the steering shaft. That usually tells you what is wrong. It has the best system for troubleshooting there is. I think my 99 day cab volvo had a crazy amount of freon needed like 6 lbs. Under that you need to run the compressor faster to get it to cool. You should get them to pump some more freon into the system to see if it fixes it. This is NOT a car A/C system, dont let them think they know how much t needs. Drop another pound in there and see if it helps.

 

Cetanediesel.



*this would be perfectly good advice if it wasn't for the act tht putting to much freon in an r134a blows up you're compressor seal so I most definately would not suggest it they put the spec on the firewall for a reason stick by it or you might end up damaging more than fixing

 

Good luck with the by the book approach. I guess you will just never find out.