A/C compressor constantly cycling, pressure good.

[tenpaiyomi]

224R cam, stock heads, 6 speed, 5.7L

As the title states, my AC compressor keeps on cycling on and off, usually at about 1 second intervals. I've hooked up manifold gauges, static pressure on high/low is ~90psi. With the car running, it's about 30psi low/200-250psi high.

I've logged the pressure switch value and it goes between 200-250psi when the AC is cycling on and off and matches the manifold gauge values.

IAT reads 86*F which is about right for ambient temperature given I am in a shaded garage, so the pressure readings are about right for ambient temperature. I'm lost as to what could be causing the AC to cycle.

The thing that is more confusing is that, when I am driving, about 80% of the time it will do this cycle on/off scenario whenever I turn it on for a second to check, and the other 20% of the time it drives fine, only turning off every now and then as would be normal for AC systems.

To add, this is a brand new AC compressor (literally, I just got a new one the other day in the case that my old one was bad), brand new lines.

I've jumpered the trinary AC pressure switch and the compressor continues to cycle on/off. As well, if I turn the compressor on via EFILive then it will turn on and stay on, so that makes me believe that there is some sort of issue that the PCM is seeing. The only issue is....what? I've looked at the conditions for the compressor to turn on and stay on and, as far as I am aware, I meet them all.

The following conditions must be obtained before A/C compressor engagement is allowed:

* A/C Pressure is between 180 kPa (26 psi ) and 2900 kPa (420 psi ).
* Engine coolant temperature (ECT) is less than 121 *C (250 *F) .
* Engine RPM is more than 550 RPM .
* The A/C request signal circuit is grounded.

Once engaged, the compressor clutch will be disengaged for the following conditions:

* A/C Pressure is more than 2900 kPa (420 psi ).
* A/C Pressure is less than 180 kPa (26 psi ).
* ECT is more than 121 *C (250 *F) .
* Engine speed is more than 5,500 RPM .
* Throttle position is 100 percent .
* Transmission shift
* ECM detects excessive torque load.
* ECM detects insufficient idle quality.
* ECM detects a hard launch condition.

Any assistance is greatly appreciated, as it is consistently over 100*F here and I am dying.

[ScarabEpic22]

It should always cycle...? All of my GM vehicles have A/C compressors that cycle on/off based on cooling demand. It is not every 1 second, but can be like 30 sec on/ 10 off.

Post you tune, what vehicle/AC setup are you running? Is the tune setup to properly control the AC installation?

[tenpaiyomi]

It should always cycle...? All of my GM vehicles have A/C compressors that cycle on/off based on cooling demand. It is not every 1 second, but can be like 30 sec on/ 10 off.

Post you tune, what vehicle/AC setup are you running? Is the tune setup to properly control the AC installation?

Yeah, I understand it should always cycle, but this is a constant cycle on, 1 sec, cycle off, 1 sec, cycle on, 1 sec, cycle off, 1 sec, repeat.

Tune attached, this is a 2003 S2000 with a 5.7 LS1, stock camaro compressor and pressure switch. As far as I am aware the tune is setup to control the AC properly.

ModifiedAC.ctz

[tenpaiyomi]

Bump :\

[ScarabEpic22]

A001 and A002 are reporting out of range, I'd recommend updating these tables to have valid data. (Set each to 99, save, change to 100, save.)

Looks like you have regular F-Body settings in there and have it wired like one (assuming so).

What are your fans doing when it's cycling? Looks like the only changes you've made there are to the Fan 1/2 on/off points. Could the pressure change be causing the fans to turn on/off which in turn causes the compressor to turn on/off?

If this all fails, could you try running a stock OS and not a COS?

[tenpaiyomi]

A001 and A002 are reporting out of range, I'd recommend updating these tables to have valid data. (Set each to 99, save, change to 100, save.)

Looks like you have regular F-Body settings in there and have it wired like one (assuming so).

What are your fans doing when it's cycling? Looks like the only changes you've made there are to the Fan 1/2 on/off points. Could the pressure change be causing the fans to turn on/off which in turn causes the compressor to turn on/off?

If this all fails, could you try running a stock OS and not a COS?

See Edit Where is A001 and A002 defined? I'm not seeing those.

Yes, stock F-Body settings and wired like one. Fans are controlled outside of the PCM, I have them wired through a few relays and a thermo switch. If the thermoswitch triggers, both fans turn on. If that AC is turned on, both fans turn on. In any given case, if a fan is supposed to be on, both fans are turned on.

I've been considering that, worst case scenario. I can throw the MAF back in to test this all.

EDIT: I see you are referring to A0001 and A0002. Those are the actual stock settings if I remember correctly, I haven't changed those. I'm not sure why they would say out of range, as the value for each states a max of 100, which is what they are set to.

[tenpaiyomi]

Also, to add, I don't believe pressure changes has any bearing in this, realistically. I can turn on the AC from a completely cold start and it does the cycling issue. As well, I've jumpered the Blue 45 and Red 14 pins with an 80k resistor directly at the PCM to eliminate wiring up to the pressure sensor, and it still cycled there. More and more this is seeming like something that is completely unrelated to the actual hardware, and something directly related to PCM/tune. I just don't know what.

To add, the hardware id for the PCM is 9386530, PCM number 12200411, though I don't know if that will affect anything.

[joecar]

...
(Set each to 99, save, exit tunetool, restart tunetool, change to 100, save.)
...

Erik, corrected your post

[tenpaiyomi]

Erik, corrected your post

Yep, already did that, reflashed, and tested, just to be safe. Same result. I'm looking into more possibilities and am thinking that this might have something to do with wiring at this point, a potential voltage drop for pin red 18 that is not feeding enough to tell it to keep it enabled.

[tenpaiyomi]

Good news, I fixed the issue. Essentially, the relay setup I had was pulling too much from a single wire. Doing some checking with my multimeter, I noticed that whenever the AC would cycle on, power would drop anywhere down to 10 to 6 volts. Pulled the AC relay 12v source off of that wire and put it on a shared wire with the starter relay 12v, and it's worked perfectly since! Thank you everybody that responded and tried to help, it is greatly appreciated.