[Dysan911]

Naturally who would be running the AC anyway when you wanna go fast but here in Florida you get into the habit of just having the AC on Auto and forget about it. I was just curious if our AC Shuts off at WOT anyway so it didn't really matter. I loaded the stock tune on our car into HP Tuners and found this screenshot that I found on the corvette forum. They seemed to be in the dark about it as well. Does this mean our AC does NOT turn off at WOT?

[Atomic Ed]

Good question. For those of us interested in adding an intercooler chiller, we need to understand what's going on here.

[Dysan911]

This was looking to be a good conversation but it just sorta fizzled out.

https://forum.hptuners.com/showthrea...sable-Settings

[laynlo15]

I believe it does.

[GT-ER]

I haven't looked at my compressor, but if it's a variable compressor then it might not even have a clutch to disengage (some do, some don't). All it does it change the rate of compression based on pressure readings from sensors as the RPM's go up.

[MR 45TH]

I’m pretty sure it does turn off.

[Wierd Harold]

It should cycle off and on according to high and low side pressures in the system.

[Dysan911]

I hear ya fellas but man I can definitely feel a difference doing a quick WOT with AC on and with it off. It just loses that snappiness and stronger pull with it on. Even the guys on the vette forum who were logging with HPTuners said they never saw the AC parameter show OFF. It always stays ON until you turn off the AC manually with the switch.

[Daves1SS]

I’m pretty sure it turns off, but sure would be nice to have confirmation of that. I’ll tell you one thing though, in the summer time, at least with the Edelbrock kit, the car nearly feels naturally aspirated when it’s hot out and the IAT’s are over 130. Their tune really dials timing back hard after 130 degrees. That’s why I freaking love this killer chiller. The car is still a beast in 90-100 degree temps and the AC blasting.

Sorry to jump off topic there somewhat. I don’t stay in it long enough at WOT to notice if the air coming from the vents is warmer or not. I would think that would be a pretty easy way to figure it out wouldn’t it? Do it on a real hot day and stay WOT for a decent amount of time with the fan on high and the AC pumping?

[TrekGTO]

All compressors have an internal or external clutch. Here is capture from CTS V2 they turn off at WOT and 3800. No idea what is going on with the 7000rpm, I run a temporary LED from the clutch relay and watch the LED turn off to verify.

[GT-ER]

Originally Posted by TrekGTO

All compressors have an internal or external clutch. Here is capture from CTS V2 they turn off at WOT and 3800. No idea what is going on with the 7000rpm, I run a temporary LED from the clutch relay and watch the LED turn off to verify.

Not true. Sanden for example has variable displacement compressors that do not have any kind of clutch mechanisms internal or external.

[TrekGTO]

Originally Posted by GT-ER

Not true. Sanden for example has variable displacement compressors that do not have any kind of clutch mechanisms internal or external.

What model Sanden?

[GT-ER]

Originally Posted by TrekGTO

What model Sanden?

http://sanden.com/pistoncompressors.html

I've actually disassembled these before. The only electronic component is the pressure valve and sometime they fail.

[TrekGTO]

Originally Posted by GT-ER

http://sanden.com/pistoncompressors.html
I've actually disassembled these before. The only electronic component is the pressure valve and sometime they fail.

Pulse width modulation is the internal clutch, which is how they have 0 output with no external clutch. Having done VW service for 35yrs this function is the leading cause for replacement. Car comes in with 0 compressor function at any rpm. I have yet to see a compressor with no clutch function but I am 2 yrs behind. SS Sedan has pulse width modulation and an external clutch.