I have a 97 Accord and every time I turn on the ac and at a stop sign or red light, theres a constant clicking sound from the compressor (not the usual intermittent clicking sound a normal ac system normally makes) and the rpm's go up and down. this makes the engine and whole car shake to a point where it seems like the car is going to shut off on me. I recently recharged the ac system but used the gauges to make sure I wouldnt overfill or go under. Any suggestions as what it could be as the ac is still throwing cold air but I dont know if this clicking is an indication that a part is about to go. Also, is it safe to drive the car with the ac on regardless of the rpms going up and down when the car comes to a stop?

 

It sounds like the compressor keeps disengaging. The disengaging of the clutch could be from too large of a gap, a faulty compressor relay, improper charging, overheating/pressurizing of the system, bad compressor clutch coil/ground, ...

Verify by turning on the car and the a/c. Make sure both radiator fans are running.

Watch the a/c clutch plate. It should spin at the same rate as the a/c compressor pulley when the a/c is turned on.

Recheck the high and low side pressures to make sure they are in spec.

The compressor should only have one wire (red) going to it. Back-probe the connector and see if the voltage stays at 12V when the a/c is on using a volt meter or a test light.

If there is a constant 12V, then something is up on the compressor side of the system.

If you the voltage switches from ~0 to 12, then something upstream (relay, pressure switch, etc..) is the problem.

 

Thanks. I will defenitely look into that. In the meantime, would it be safe to drive the car like this even though the rpms are constantly going up and down. The strange thing is, is that seems to pick when to do it, but most of the time is when it comes to a stop sign or red light. You think the throttle body might be clogged as well?

 

A dirty throttle body, throttle plate, and idle air control valve might cause this problem. As idle gets too low, the voltage may decline enough under load to cause the compressor clutch to "drop-out", and as soon as idle speed improves it would re-engage, and repeat.

Clean throttle body, plate, and IACV carefully w/ throttle body cleaner.

good luck

 

it sounds to me like you overcharged the system

Going just by the gauges is not a very good idea , if any components ( exp valve, blockage in system, compress reed valves etc etc ) does not function properly the pressures could be off, also ambient temp has an effect on the pressures ,,, best way to recharge a/c system is to totally empty it, put under a vacc and install the proper amount

 

So I cleaned the throttle body with throttle body cleaner and so far so good..no more clicking of the compressor while stopped, or the engine shaking violently. Also rpms are no longer going up and down as they were as well. Hopefully this fixes it permanantly.

 

Can you detail the process of cleaning the throttle body for me? I'm going through a similar low-idle issue with A/C turned on.thanks!!

 

its just a matter of removing everything in order to expose the opening of the throttle body and spraying it with throttle body cleaner. Then wiping it down and making sure everything is nice and tight when putting everything back together. I used the spray from STP brand. It was a little easier on mine since I have a cold air intake, so it was just basically removing the tube and cleaning the inside of it and the plate inside as opened and closed.