Anybody here with Clark's A/C installed? Compressor issue

[66vairguy]

When folks started complaining the Sanden SD5 (five piston) compressors were making noise (reported on other car forums so not a Corvair issue) Clark's started selling the Sanden seven piston SD7H15 #4663, BUT the pulley was smaller vs. the SD5.

If you read the Sanden charts the HD units have a 4,000 compressor RPM clutch cycling limit except for an occasional increase to 6,000 RPM. With the Clark's Sanden #4663 and the Corvair A/C pulley (6.125"), this limits you to about 3,200 engine RPM cruising with the compressor clutch cycling on and off - hmmmm. Depending on tire size and axle ratio that could be less then 70MPH.

I looked in the catalogs and found a SDH715 #4664 with the larger compressor pulley used on the SDH5. This unit also has a diode in the connector to prevent reverse EMF arching of the Corvair compressor clutch control points when the compressor clutch power is cycled. The bigger pulley on the #4664 allows a constant cruising engine speed of about 3,400 engine RPM, which should allow 70MPH cruising.

I ordered a Sanden #4664 and it fits fine and uses the same belt recommended for the old SD5 compressor.

Any thoughts from the A/C folks????

[RexJohnson]

You could just use the smaller smog pump pulley?

[vairmech]

You could just use the smaller smog pump pulley?

My thoughts exactly.

[66vairguy]

Thanks for the input.

Yes the 5.0" smog pulley would get the ratio nearly 1 to 1 allowing up to about 4,000 engine RPM without exceeding the Sanden compressor clutch RPM limit.

The second generation A/C pulley was about 5.5" and probably the best fit.

Not sure how the 5.0" smog pulley would affect cooling at idle, but it isn't a huge difference at that low RPM.

Only issue is those 5.0" smog, or 5.5" second generator A/C pulleys aren't that common!!

When I replace the failed NEW expansion valve --- I get back and comment.

[Frank DuVal]

Not sure how the 5.0" smog pulley would affect cooling at idle, but it isn't a huge difference at that low RPM.

Cooling of?

Engine fan runs off of harmonic balancer, not add on pulleys.

[RexJohnson]

I think he meant A/C cooling?

[66vairguy]

I think he meant A/C cooling?

Yup --- Thanks Rex. The 5.0" smog pulley will turn the A/C compressor a little slower at idle and affect evaporator cooling.