What are the air conditioning options for a 1985 Mazda RX-7 FB?

Your options for adding or restoring air conditioning in a 1985 FB RX-7 depend heavily on whether your car originally came with it. AC was an option on these cars, usually installed at the port before dealership delivery.

If your car originally had AC but the under-hood components were stripped, you are in luck—your dashboard controls, cables, and under-dash evaporator housing should still be intact. If it was a non-AC car, you are starting from scratch and will need to source everything.

Here are the main routes you can take. Expect this to be a Moderate to Hard project depending on how many parts you have to track down.

1. Restore the Factory System (OEM Style)

You can still buy several of the primary components brand new, including the compressor, condenser, receiver/drier, and expansion valve ².

However, you will have to hunt the classifieds, eBay, or Facebook part-outs for the vehicle-specific hard parts:

• Compressor and condenser mounts
• Evaporator core and housing
• Wiring harness
• Dashboard controls and cables (if your car never had them)

A note on hoses: Do not trust 40-year-old factory AC hoses. The standard practice is to make your own custom hoses using modern barrier hose and a crimper, sourcing fittings from suppliers like ColdHose.com ². This is safer, more reliable, and allows you to route the lines much more cleanly than the original port-installed setup.

2. Refrigerant Conversions

The original systems ran on R-12, which is obsolete. If you are building or restoring a system, you will need to convert it to a modern refrigerant.

• R-134a Conversion: This is the standard route. Because R-134a is less efficient than R-12 in these older systems, it is highly recommended to fabricate mounts to fit a larger condenser to help bring the cooling performance up to modern standards ².
• R-152a (PC Duster) Conversion: This is a popular alternative in the community that often yields colder vent temps than R-134a. If you go this route, you must completely flush the system of old mineral oil (using brake cleaner on the hard lines, and gravity-draining the compressor), install a new receiver/drier, and use green O-rings ³. You will need to fill the system with synthetic ester oil—typically around 1 oz in the drier and 5 oz in a Sanden-style compressor ³.

Safety Warning: Whenever handling refrigerants, wear latex or nitrile gloves to prevent frostbite, and keep diluted car wash soap handy in case of accidental skin contact ³.

3. Universal Aftermarket Kits

If your car never had AC and you cannot find a donor car for the under-dash evaporator and controls, you can bypass the factory setup entirely. Many owners install universal "hot-rod" style aftermarket AC kits ².

These kits come with a standalone under-dash evaporator and blower unit, their own switches, and a modern Sanden compressor. You will still need to fabricate a compressor bracket for the 13B/12A engine and mount the universal condenser behind the grille, but it completely eliminates the need to hunt down 40-year-old Mazda interior plastics.