My 94 Jeep Grand Cherokee Laredo 5.2 won't shift into overdrive. I understand that if the ECM has certain trouble codes, it won't allow the trany to shift into overdrive. My codes are 33 for a/c clutch short/open and 22 for engine temp sensor low voltage. Would either of these cause my problems?

Neither of those DTCs should prevent overdrive operation.
Three separate issues are likely going to require three separate approaches.

Well, where do I start?

Well, where do I start?
You've already started!
Prioritize your symptoms and decide the best strategy based solution.
Your best bet is to throw down and buy the proper manual for your vehicle rather that try piecing it together from here.

Consider the mileage on the Laredo and how well the transmission has been cared for. Examine the fluid--is it pink or brown (burnt smell)? Have you performed regular preventive maintenance on the ATX? If not, determine if you are willing to spend a little money to drop and clean the pan, change the filter, and refill with ATF+4. It may make a big difference. These steps should really be performed every 30,000 miles. If you do, the ATX will last the life of the vehicle. If you don't, sludge, oxidation, and premature clutch pack wear develops, which prevents proper shifting. The condition of the fluid affects hydraulic pressures, clutch life, and general wear. This link may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-5.html#post552241