AC compressor vs engine revs
Discussion
How does the AC compressor cope with high rpm?
Is the compressor spec'd to run at engine redline, and yet also deliver enough pressure to meet cooling needs at idle?
At higher rpm does the extra pressure just get bypass'd back into the low side of the system?
Ive always turned off my AC when hooning as, in my head, regularly spinning the compressor much faster than in normal driving wouldnt be doing it much good.
But then it dawned on me, that if i had thought of this, then surely the manufacturer has too.
Anyone know?
Thanks
Is the compressor spec'd to run at engine redline, and yet also deliver enough pressure to meet cooling needs at idle?
At higher rpm does the extra pressure just get bypass'd back into the low side of the system?
Ive always turned off my AC when hooning as, in my head, regularly spinning the compressor much faster than in normal driving wouldnt be doing it much good.
But then it dawned on me, that if i had thought of this, then surely the manufacturer has too.
Anyone know?
Thanks
I don't know if most A/C compressors or systems have pressure regulation but they do use a safety switch that just cuts the power to the clutch if the pressure becomes excessive. If it's generating too much flow and the pressure climbs beyond what's acceptable then it will just disconnect by itself. Probably this is the case in basic systems and they're just designed in such a way that it will never create too much flow to trip out the safety switch unless something is broken.
If there is a pressure regulator then it will just bleed the pressure back to the low side and whatever excessive flow there is will just be going round in circles.
That said most modern cars (probably anything produced after about 1990) will likely have a control system which will disconnect the A/C compressor when you're running at high throttle openings or RPM anyway in which case there's no point turning off the A/C for performance and you'll get sweaty for no reason as it will only be running when you're off the throttle anyway
If there is a pressure regulator then it will just bleed the pressure back to the low side and whatever excessive flow there is will just be going round in circles.
That said most modern cars (probably anything produced after about 1990) will likely have a control system which will disconnect the A/C compressor when you're running at high throttle openings or RPM anyway in which case there's no point turning off the A/C for performance and you'll get sweaty for no reason as it will only be running when you're off the throttle anyway
Varriable displacement compressor:
https://macsworldwide.wordpress.com/2013/05/29/var...
Back in the day, AC compressors were fixed displacement, and yes, these had issues with operating range. They had to be capable of maintaing operation at high revs, and yet also work at idle, where possible.. Often, they would simply be clutched out (ie the magnetic clutch would be disengaged) at high revs to avoid over pressure in the system, or rely on the systems High Pressure Switch to do that (which interupts the feed to the mag clutch)
https://macsworldwide.wordpress.com/2013/05/29/var...
Back in the day, AC compressors were fixed displacement, and yes, these had issues with operating range. They had to be capable of maintaing operation at high revs, and yet also work at idle, where possible.. Often, they would simply be clutched out (ie the magnetic clutch would be disengaged) at high revs to avoid over pressure in the system, or rely on the systems High Pressure Switch to do that (which interupts the feed to the mag clutch)
Benbay001 said:
How does the AC compressor cope with high rpm?
Is the compressor spec'd to run at engine redline, and yet also deliver enough pressure to meet cooling needs at idle?
At higher rpm does the extra pressure just get bypass'd back into the low side of the system?
Ive always turned off my AC when hooning as, in my head, regularly spinning the compressor much faster than in normal driving wouldnt be doing it much good.
But then it dawned on me, that if i had thought of this, then surely the manufacturer has too.
Anyone know?
Thanks
It doesn't, they're clutched, they disengage so do not operate at higher rpm'sIs the compressor spec'd to run at engine redline, and yet also deliver enough pressure to meet cooling needs at idle?
At higher rpm does the extra pressure just get bypass'd back into the low side of the system?
Ive always turned off my AC when hooning as, in my head, regularly spinning the compressor much faster than in normal driving wouldnt be doing it much good.
But then it dawned on me, that if i had thought of this, then surely the manufacturer has too.
Anyone know?
Thanks
Max_Torque said:
Varriable displacement compressor:
https://macsworldwide.wordpress.com/2013/05/29/var...
Back in the day, AC compressors were fixed displacement, and yes, these had issues with operating range. They had to be capable of maintaing operation at high revs, and yet also work at idle, where possible.. Often, they would simply be clutched out (ie the magnetic clutch would be disengaged) at high revs to avoid over pressure in the system, or rely on the systems High Pressure Switch to do that (which interupts the feed to the mag clutch)
Are these that common now? My 2003 Jaguar has one but my 2019 MX5 doesn't, which surprised me as I'd assumed they'd taken over for efficiency reasons.https://macsworldwide.wordpress.com/2013/05/29/var...
Back in the day, AC compressors were fixed displacement, and yes, these had issues with operating range. They had to be capable of maintaing operation at high revs, and yet also work at idle, where possible.. Often, they would simply be clutched out (ie the magnetic clutch would be disengaged) at high revs to avoid over pressure in the system, or rely on the systems High Pressure Switch to do that (which interupts the feed to the mag clutch)
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