Is idle setting supposed increase with the Air Conditioning on?

[wrkey]

In most vehicles I have owned, there is a component that increases the idle setting with the AC is turned on. On my 92 Geo Metro is also increases the idle when the voltage drops a certain amount. I have noticed that my DeLorean does not do this so I have to do it manually. If I am at idle with the AC on the voltage guage drops well below 12 and if the lights are on it's even worse.

So.. is there supposed to be an idle increase? If so and since I'm not seeing that, where should I look first to fix it?

[WelmoedJ]

In most vehicles I have owned, there is a component that increases the idle setting with the AC is turned on. On my 92 Geo Metro is also increases the idle when the voltage drops a certain amount. I have noticed that my DeLorean does not do this so I have to do it manually. If I am at idle with the AC on the voltage guage drops well below 12 and if the lights are on it's even worse.

So.. is there supposed to be an idle increase? If so and since I'm not seeing that, where should I look first to fix it?

In a properly working and set DeLorean the idle RPM increases once the A/C starts and decreases when it stopts.
Usually you will see a slight drop in voltage when the A/C kicks in.
That's normal.

If the voltage drops too far, i.e. below 12 Volts your electrical system or it's parts may have developed obstructions.
These can be bad ground, corroded contacts in connectors or even the fan motors themselves going or being bad.
You should check all these to find the cause of your malfunctioning system.

BTW: a sound electrical system should be able to provide as much as over 13 Volts on the gauge.
Fans kicking should make the voltage not drop below 12V, more just dip and then return to the "normal" position.

[jawn101]

In most vehicles I have owned, there is a component that increases the idle setting with the AC is turned on. On my 92 Geo Metro is also increases the idle when the voltage drops a certain amount. I have noticed that my DeLorean does not do this so I have to do it manually. If I am at idle with the AC on the voltage guage drops well below 12 and if the lights are on it's even worse.

So.. is there supposed to be an idle increase? If so and since I'm not seeing that, where should I look first to fix it?

If your voltage is dropping that much, you have other issues to address - most likely bad grounds or a bad alternator. There is nothing in any of the systems to increase the idle with the A/C running, but in a properly working system there should be no RPM or voltage drop when it is.

[sdg3205]

the idle speed motor should compensate for the load. check that it is functioning. it should buzz with the key on the second position. If you can, remove it and check the valve. after 30 seconds it should slowly rotate. Dave Swingle told me this trick and it has solved a lot of issues, like poor mixture and AC load idle.

Just because it buzzes, doesnt mean it working, they can seize.

[DMCMW Dave]

In a properly working and set DeLorean the idle RPM increases once the A/C starts and decreases when it stops.


It will not increase, it should just stay the same i.e. compensate for the load but try and hold 775-ish.

The idle ECU does not "know" that you turned on the A/C, it just notices that the engine idled low and will open the ICV more to compensate. This assumes that base idle is set correctly, if you have the throttle set too far closed, there may be no range left in the ICV to open any extra. It also assumes that the ECU and ICV are working at all.

It's a relatively "slow" circuit so when the A/C goes on the engine may dip for a short interval, and when the A/C goes off it may go faster for a short interval.

[Chris 16409]

If you would like this feature on your DeLorean, Dave M's solid state Idle ECU can bump idle when the A/C is turned on.