That depends on if yours has the Cummins ISX, VED12, VED13, or VED16. I believe there was a VNL780 in production when the Detroit Diesel 60 Series and Caterpillar 3406E, C12, C13, and C15 were available options for Volvo, as well.
Assuming you're referring to a Volvo VNL 780 truck, with the double bunk sleeper, 12'6".
The VNL series trucks are. Volvo Trucks is still a part of Volvo A.B., although the car manufacturer is not.
There is none it is all number coded
For the North American market, it was just the VNL series, for which the model number was (and still is) based on the length of the sleeper.
Assuming you're referring to the North American VNL series, it should be in the centre of the dash.
On the VNL and VHD models, there's a lever under the steering column. You pull that out to open the hood.
There should be a sticker near the belt which has a routing diagram on it. Barring that, we'd need to know if the truck has the Cummins ISX, Volvo VE D12, or Volvo VE D16 engine in order to provide you this information.
You didn't specify if you were talking about a Volvo car or Volvo truck.... in this instance, I'm going to assume you're talking about a truck, such as a VNL, VED, or VHD series. The simple answer is, no, that model year is not CARB compliant. Those predate the DPF, and retrofitting them is both expensive and ineffective.
Freon itself was largely phased out before 1998, but it would also be dependent on the model of the truck, as Volvo manufactures several different types, for a number of world markets. For example, they have the NH, NM, FH, FM, etc. series trucks, the VNL series trucks for the US market, etc. You'd be a bit more specific about what model Volvo truck it is.
In the VNL/NH series, it's in the centre of the dash. You pull out the cupholders, and there'll be two screws exposed which you have to remove. Once that's done, you simply pull the panel up, and the fuse panel is exposed.
I can't say with 100% certainty, but I know the hood latch on the 07 VNL780 I'm driving is located at the bottom of the steering column. It's possible that the same configuration is used on the 97 - 2004 VNL series trucks.
Voltage regulation is just the percentage change in voltage at the receiving/sending end of the transmission line from no load to full load. It is given by ((Vnl-Vfl)/(Vnl)) X 100%. Typically Voltage at receiving end is known to us and for the sending end Vnl is given by Vs/A. Where A is given by the ABCD parameters of the transmission line and Vs = AVr + BIr.