A/C compressor puts unusually high load on engine. ('97 Plymouth neon)


Thanks to NYBo I fixed the first A/C problem and it turns off now. I also recharged it and I get cold air when it?s on so it?s working fine. However when the A/C compressor kicks in it seems to be putting a pretty big load on the engine. There seems to be a loud whine/hum from the engine and I can feel a vibration through the accelerator. Both the vibe and the noise come and go in time with the compressor. The noise varies in pitch with the RPM of the engine and is loud enough that other people can hear it as I drive by. It?s not a metallic grinding noise. There is also noticeably less acceleration and power.

My first thought is that the compressor or the compressor clutch needs to be replaced but I figured it was worth posting here for other ideas before I do that.


You need a system (AC) pressure check possible high side to high possible over charge,how did you determine correct charge weight. These pressure readings really help in a diagnosis. they are important. Another reason for high high side pressures is no fan operation but you say concern is instant. Pressure reading can diagnois a compressor concern (mainly poor AC performance)


I would second the concern for the system being overfilled with freon. As oldschool stated, putting the gauges on the high and low side will tell a lot. It will not tell you the exact weight of charge in the system but will tell you if the condensor and receiver/dryer are bound up with excess liquid. The only accurate way to get the correct charge into the system is to evacuate/recover the freon and refill it with the correct weight. This is usually a job to a auto HVAC technician as the equipment and training preclude DIY fixes. So you should get it to a HVAC shop.

My idea.


In addition to the potential mis-charging I would suggest that many cars automatically increase the idle when the A/C kicks in. That system may not be functioning in your car.