Installing new speakers on a '93

Yesterday, I bought a cd player for my car only to find that audio only comes out of the right front speaker. I hear no sound on the left channel and I'm just assuming that my '93 has no rear speakers. This obviously makes listening to CDs suck. I had some friends who are major auto enthusiasts install it for me and they didn't have to splice any wires or anything because I bought a smart cable so that made things simpler. So does anyone know if something maybe wasn't connected properly? Should I just shell out some more money for new speakers?

I would test for continuity with a multi meter first. You may simply have a bad wire or connector somewhere. Good Luck.