[chevyrestoguy]

You have to weight both options, factory and aftermarket. In the end, the aftermarket will probably come out ahead, if you're going on total money spent. The aftermarket stuff is much more advanced in technology than the original stuff, and is usually much more compact.

But, I like the look of the original vents, and I'm one of the guys who likes it when the original stuff is working and operational. You can make the factory system work great, but you have to be prepared to make some retrofits. First of all, you're probably never going to run R-12 because of the cost of the refrigerant, so you will need to do the steps required to convert the system to R-134.

First of all, the condenser will probably need to be replaced because after 50 years, because they just get brittle and start falling apart. The fins are a soft material, and they'll usually break when you try to straighten them. The newer style condensers are better designed for R-134. Usually, they have a larger surface area, and according to the experts, it's required to help dissipate the heat. So, replacing the condenser is highly suggested. Also, nearly every factory installed R-134 system since it's introduction has had an electric fan to help cool the condenser. An electric fan blowing on the condensor greatly helps a R-134 system. If you don't like the look of an electric fan, then having a high-quality clutch fan is highly recommended.

Always, always, always replace the filter/dehydrator whenever you have the system apart.

Our original systems are equipped with a Suction Throttle Valve (STV), and finding a replacement is getting tougher and tougher. You can change it over to a POA valve, which is totally compatible and will interchange. Make sure the POA valve you're getting is calibrated for R-134. The two refrigerants react differently, and you'll need a POA valve that's calibrated to bypass at a different rate than R-12.

The older axial compressors (A6) work great with R-12, but the newer radial style compressors work even better with R-134 because they're more efficient. The R4 compressors that GM used from the early '80s to the early 2000s are not known for living a long life, but they're readily available and pretty inexpensive. The later, smaller compressors like the Sanden are excellent and work well.

The old AC lines can leak due to old age, and the R-134 has a real tendency to leak past the old worm clamps that GM used back in the day. Making new lines with RingLoc fittings will help eliminate any refrigerant loss.

Change out every O-ring in the system to ones that are R-134 compatible.

Make you use the correct PAG oil for R-134!

You can make your factory system work pretty well by upgrading the condensor, dryer, POA, and compressor. Just remember that after all of that upgrading, you'll probably be over the price of an aftermarket set-up.