RPM's and A/C?

Dean Lampe · 12-30-06, 10:37 AM

How fast can you turn your A/C compressor before it comes apart? Do they have a clutch in them that will allow them to free wheel with out harm? I am thinking of the track days and how hard it would be to take the belt off everytime I am at the track. If you spin the 6000, 7000, 8000rpms will they exploded?

Ron Earp · 12-30-06, 11:21 AM

Most OEM AC installations have a switch that disengages the compressor at WOT. This works via the electromagnetic clutch that all modern AC units have and a position switch on your carb. My old 85 5L notchback had a AC cutswitch on the carb, you could probably rig up something similar to that. ECU cars can simply use TPS output to determine WOT.

Ron

Dean Lampe · 12-30-06, 01:57 PM

I was mainly talking about when the A/C is off and I am doing laps. Does the rpm's effect the compressor if it is not turned on? I don't want to have to reach back there and take the belt off.

Ron Earp · 12-30-06, 02:06 PM

Sorry Dean, I missed that somehow.

I think you will be fine. There are many engines that turn higher RPMs than the average GT40 (Honda S2000, Audi S4S, RX8s, Lotus Exige, Esprit, etc) that I see at tracks frequently. All have AC and will have to have approximately the same pulley ratio as you do to make sure the AC will work in the intended cruise range on the highway. I have never heard of anyone having issues nor have I experienced any problems myself. The clutch will free wheel and won't turn the compressor at all, and the pulley clutch assembly seems to be fine with high RPM.

I remember some years ago looking on the Sanden site or literature and it listed the RPM range for compressor functioning as well as max pulley speed. When I did the calculations for my RF and the pulley set I had there were no issues, free wheeling or engaged.

Ron