What is wrong if the rightside is hot or no air at all when the a/c is on

Tail lights are usually on the same circuit so technically, they're already wired together.

Sounds like you have a loose connection somewhere. You will need to remove the light and start tracing the wires.

The thermostat is located on the rightside of the truck as viewed from the drivers seat. Follow the upper rad hose it connects to the thermostat housing. A good way to check if the thermostat is stuck is when the motor running and fully warmed up squeeze the hoses if it is hard then the thermostat is stuck. Another way is with the motor hot feel if the upper rad hose is hot; if it's not then your thermostat is stuck. Hope this helps.

what kind of car? does it have leftside/rightside control?

may be you should make a diagnostic by this tool: Lexia-3 pp2000

try a new flasher

start by checking all your fuses, next if fuses are good then check the blower motor resistor, these resistors go bad often,its located in engine compartment,on the rightside on blowermotor housing

my heat blows hot air on passenger side and cold air on drivers side when i have it hot air..why is that?

low a/c charge or bad left blend motor.

hate to ask but did you put the thermostat in rightside up ? and someone else might be right did you bleed the system and get the air out of it? sometimes there is a air lock that will drive you crazy.. another thing when you replaced the water pump did it heat up before you changed it ?? if so did you put right gaskets on it for correct flow.. ? thanks Jerry if you have more holler