Cadillac Repair: Code F41, r 134 freon, r 12 freon

Question
HI I got a Fleetwood D'Elegance 1988 4.5 l FWD. I retrofitted my AC to R134a long ago. Ever since my AC never worked fine. BCM kept throwing codes F46/47. No I replaced orifice tube, accumulator and now my AC doesn't have a leak, pressure is good on both sides and the air blows cold. But still my BCM throws code F46/47 and switches from auto to econ. I replaced now my BCM with another from a 88 deville. (I think these are the same BCMs right?) After replaceing it immediately the code F41 comes up, the Cooling fans Light comes on and a strange noise comes from behind the glovebox. After couples of seconds it stops and then comes again stops again.... This is only when auto is chosen, when I switch to econ the light disappears and the sound stops. Any help? thanks

Answer
The reason that the codes are displaying is that the low pressure sensor is calibrated for R-12 freon. It is NOT compatable with R-134 freon. Your only option is to keep resetting the computer or put the R-12 freon back in the system as there is NO sensor available to resolve this very very common problem.