Nippon Denso Corvair A/C Compressor Conversion


Replacing the old GM A6 air conditioning compressor with a Nippon Denso could be considered an easy and viable substitution for the popular Sanden replacement. It was for me anyhow.


Setup prior to the ND compressor installation


Iím considered frugal by myself and most. My wife, however, says Iím cheap. Either way Iíve wanted to replace my original A/C compressor due to the weight and lack of efficiency. Asking around, I was offered an old R-12 Sanden compressor by another NTCA club member. After removing a substantial amount of old grease from the body of the compressor I discovered this was not a Sanden as we thought but a Nippon Denso. This compressor came with a clutch assembly mounted on it and it had a single V belt pulley for the drive. 


While I had considered buying an aftermarket mount from one of the vendors, being frugal (okay, cheap) I decided to build my own utilizing the original GM mount as provided by GM. What seemed to be a daunting task at first I decided to consider it a challenge.


After the installation


After much deliberation I decided to base my mount using a strengthened threaded rod, 5/8 inch in diameter. Since this compressor was designed as a four bolt mount I drilled out the original threads from each mounting leg and pushed the threaded rod thru using a nut and washer on each side of each leg.  A piece of flat iron was a adapted to fit the front part of the original compressor mount attached to the old A6 and two holes drilled thru the iron to accept the threaded rod which also had a nut and washer attached on each side. The rear part of the mount was made from angle iron and attached to the original mounting piece bolted to the opposite end of the A6. This angle iron provided an area to drill and thread a hole which was used to provide a means to adjust the belt tension. One note: While the rotation of the compressor is indicated to be clockwise, the compressor works fine running counterclockwise.




By using threaded rod in this fashion it allowed me to adjust the compressor from front to rear to align the compressor pulley with the drive pulley attached to the harmonic balancer.


The only other problem to deal with once the compressor was mounted was a means of adapting the O ring style connectors that the ND compressor came with to a barbed type connector that I needed to adapt to my present refrigeration hoses. This was accomplished by going to a local automotive A/C shop here in Dallas where I was able to purchase fittings that were exactly what I needed and at a very reasonable price

Once the installation was completed and the systems charged with R-12 I noted some interesting differences in the operation of the two compressors. First, the new compressor does not pump as much refrigerant thru the system at idle as the original did. This resulted in diminished cooling while sitting at a light. Second, was a reduction of vibration, noise and assistance needed from the automatic throttle advance to maintain a smooth idle. Iíve noticed no difference in performance of the A/C system as far a keeping the vehicle cool but I wasnít expecting any. Other than what I previously stated, the cooling of the cab is neither better nor worse than before the compressor replacement. I still have to keep all the windows closed to get adequate cooling in our 100 degree heat but my objective was accomplished in that my Corvair is a much smoother running car, especially at idle, than it was previously. The total installation cost, for me, was in the neighborhood of around 30 dollars.


The original installation. What in the world were they thinking?


One final thought. When you remove A/C components take just a little extra time to seal off the refrigerant lines, ports and what ever other internals are exposed to the atmosphere with tape, preferably with a good electrical tape. It's even better if you can mechanically seal openings using plugs, hose clamps or soldering then pressurizing the component with a refrigerant or nitrogen. This helps to keep moisture and dirt out of components that can corrode internal parts.


NOTE: Since this A/C I found that the Corvair, at idle, does not move enough air across the condenser and the high pressure side tends to rise. I added a couple of inexpensive electric fans to the condenser coil that are wired to operate when the A/C is turned on and that takes care of the problem.


Should you have any questions concerning the installation or alteration of a Corvair A/C system, feel free to email me and Iíll do my best to answer any questions. email link


This article was completed on Aug 27, 2005 and updated on Mar 17, 2013.

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