1997 850 Air Conditioning Affecting RPM/Acceleration

ahess92 · Post by **ahess92** » 18 May 2015, 13:14

Hello all,

I've noticed in the last couple of months that when my A/C is turned on, my RPMs seem to drop slightly for a minute or so, and then they return to normal. Both the drop and the return to normal are accompanied by a "click", which I am taking to be some sort of A/C mechanism engaging and disengaging. I have checked, and this does not happen when I turn the A/C function off. I'm a self-professed amateur when it comes to automotive diagnosis, though my suspicion is that it has something to do with the compressor (full disclosure: my brother actually suggested this as a possible problem - my original fear was that it had to do with the transmission... Again, I'm an amateur). I've done some research on compressor units and they aren't terribly expensive, though that would be money I'd rather not spend if it isn't the problem. Thoughts? Thanks in advance!

Post by **abscate** » 18 May 2015, 15:41

D Completely normal. On Volvo the AC compressor is cycled on / off to provide the needed cooling load. As the clutch pulls in, the engine is loaded and the rpms will fluctuate

Post by **JRL** » 18 May 2015, 15:46

Plus A/C (on) uses a lot of HP, more than you would think!

mika · Post by **mika** » 19 May 2015, 07:54

So which option is better: turn off the AC when at a long stop light, or dealing with the compressor kicking on and off and bogging the engine down uncomfortably? Is turning the Ac on and off at lights "bad" for it?

Post by **misha** » 19 May 2015, 09:39

Ac compressor will have frequently cycling on & off ONLY when system is low on refrigerant.

When system is properly serviced and when refrigerant is at proper level,you will hardly ever hear it cycling.
Take the car to professionals who are servicing ac systems and let them check the condition of your ac.