gabep

If it's a broken wire it will be in the loom. It's a usually a black piece of plastic that looks like a snake. You have to open it or split it to get to the wires. As to other causes, it could be a number of things too detailed to go into.

Usually a broken wire in the wire loom that is in the trunk that feeds the trunk lid. It is a usually a black corrugated appearing tube. You have to open it up and check all the wires and reconnect any broken ones. You can use wire nuts, no need to solder.

Look here. Due to Japanese smog rules most engines have to be replaced at about 50,000 miles. http://www.tigerjapanese.com/index.php?page=shop.browse&category_id=7&option=com_virtuemart&Itemid=26

http://www.rockauto.com/

By your questions it's obvious you need to take it to a qualified A/C repair shop. You can convert the system but it must be done by a qualified shop.

disregard

Just a note. When the wheels are installed be sure the torque values on the lug nuts is correct. If not, the rotors will eventually warp and you will have to replace them.

Look here. In Japan they must replace the engine every 50K miles or so because of pollution. http://www.tigerjapanese.com/index.php?page=shop.browse&category_id=7&option=com_virtuemart&Itemid=26&vmcchk=1&Itemid=26