ecm no codes

hello I am new here and have a 1994 camaro. The ecm wil show no codes not even a code 12. after taking it to a shop they said it needed a new computer so I put 1 on it was new and flashed for my car still get nothing. Also a/c compressor will not come on the 2 problems appear to be linked together. Anyone have any ideas?

94's don't flash codes with the check engine light, you unfortuantely need a scanner for OBD I (hybrid) with the OBD II style connector cable.