AC Circuit Problem

you need a governor with a long time constant so it pushes the accelerator.

All common portable AC generators are equipped with these, a little study of one will help you out

G'day,
You'll need a frequency switch that cuts the supply to the A/C compressor clutch at a pre determined frequency or engine speed. In Australia, they were fitted to 4 cyl carby vehicles to stop your problem. If you can't get one through you local A/C fitter, try Europe , U.K. or Aust.

Alternatively, build your own from a kit. Jaycar, http://www1.jaycar.com.au/, supply these by mail order and they have a US outlet. The kit ref is KC5378. I've used this my self and it i very versatile.

However, having said all that, I think the 307's ECU should control your idle speed. Check the stepper motor that controls the idle. Does the engine "fast idle" when starting from cold?

You could also check all the relays connected with the ECU as I have found that removing the relays and swapping them around with other relays of the same rating in the car will often rectify many faults associated with poor connections. If not, see a service tech re the ECU's idle control

Regards,

RRV

Hello Guest,

It sounds like you have had some pretty good answers. But would it be a simple case, of the change in pulley size to a larger one. It would mean the alternator is working faster all the time though. Can you tell me the alternator and what it is fitted to please?

Take care and I will be looking in to see how you get on!

Two replies so far have interpreted "AC" as Alternating Current; I suspect you mean to imply Air Conditioning? Another assumption I am making is that this is an automotive system; most cars have a solenoid valve that increases idle rpm whenever the airconditioning compressor is engaged (valve coil in parallel with compressor clutch). This may be defective, in which case repairing it will solve your problem quite simply. Typically, the valve increases bypass air around the throttle plate, and the engine's computer does the rest, but there are other systems.

A voltage-sensitive relay hooked to the alternator output leads could be put in series with the compressor clutch. Using the NO (Normally Open) connections, the clutch would not receive power until alternator output rose sufficiently to actuate the relay. Or do you have another reason for choosing the precise rpm (1160)? Is that actual alternator rpm, or engine rpm, or . . . ? What is special about that speed?

Suggestion: when asking a question on CR4, or ANYwhere that engineers might bcome involved, provide as much information as possible. Spell out abbreviations and acronyms on first mention - there are likely hundreds of possible uses of "AC" for example, and they vary around the globe as well as between industries. Most of us can discard or ignore redundant or superfluous information, but we can only guess at what is missing.

The standard solution to this problem is to increase the throttle setting when the AC clutch is engaged. In carburetor days, this was done with a solenoid that changed the position of the idle stop. Now it can be done in several ways, with a common one being an electrically-operated vacuum solenoid valve which opens a small throttle bypass passage, supplying more air to the engine (with the injection system naturally handling the mixture control). Usually, you would want the AC to work with the engine idling, so only having it work at speeds over 1160 alternator speed might not provide the comfort you want. However, most alternators turn at over 1160 at engine idle -- a 2:1 drive speed is not uncommon, and a 580 rpm idle is on the slow side.

You may need to supply more info on the type of fuel system and the speed ratio between the engine and alternator. Normally this function is built in -- are you working on something other than a car?