I am looking at getting a 1990 DX hatch. My only issue is that it doesn't have ac. From my understanding they never came with ac. Is there a way to add ac? There are a bunch of early 90's civics near me at junkyards and such that do have ac. Is it simple as take it from an EX or something and just swap it or is there a kit? Also sorry if this has been answered just joined the forum!

 

A/C was a dealer option so I think it could be added to any 88-91 Civic. You would need several parts that are no longer available so junkyard is going to be your best source for those parts.
I recommend that you use as many brand new parts as possible if you want it to last. New parts would include:

1. Compressor
2. Condenser
3. Evaporator
4. Expansion Valve
5. Hoses
6. Drier
7. Compressor drive belt
8. Schrader valve
9. O-rings
10. Refrigerant and Oil
11. Pressure switch

The used parts list is pretty short:

1. Wire harness
2. Compressor mounting bracket with associated adjuster, pullies and bolts
3. Electric cooling fan and associated mounting parts
4. Hard lines (the hose sections that are actually pipes)
5. A/C button for the dashboard
6. The plastic box that houses the evaporator

I would recommend looking at this thread for a possible better solution.