A\C cutting out constantly.

Ok, so it's starting to get warm here in az. As in 90° already. Running on the highway I can't seem to get my A\C to stay on above 65mph, or below 40mph, and it won't run while accelerating and once it cuts out, it doesn't want to come back on, I have to insist it does before it decides to. I've checked the control panel, the pressure switch and the wiring to and from the compressor and it all seems to be just fine. I have removed the belt and engaged the clutch with the engine off, and the compressor spun, but it took more effort than I think it should, but it did spin. I have a feeling that the ECM is shutting it off because of the drag it's causing on the engine, anyone have any better ideas?

I have a factory service manual at home I can check.  Won't have a chance until Saturday, but if you're interested I can PM you my phone number for a reminder call/text.

is this at all throttle positions? i know WOT shuts it off,and at least from what i saw on the tables for the 2nd gen ecus that throttle% can be tuned

Yup. It has to be a snafu in the ECM. I may try and bypass ECM control of the AC system by routing the A/C signal through the pressure switch to a relay then directly to the compressor. Essentially like the good ol' days of carbed engines with A/C. I'll just need to figure out the pinout of the pressure switch and the two pin plug on the compressor.

In testing yesterday it seemed the connector on the compressor only saw ground, which could make this a bit more difficult, but that could just be from the ECM fault. Research will have to be next.

It would appear from the wiring diagram that pin A2 on the ECM is the control circuit for the AC and is a ground switch for the relay. I hadn't though to check the plugs and wires on the ECM itself to see if it's just not getting signal. It does however appear that the relay is wired such that if I just ground this control circuit then the relay will just lock open and the switch on the dash, which is inline with the pressure switch, will have sole control over the direct line of current to the compressor, which I don't know that I like, but I suppose it has to handle it since it works that way from the factory. I'm perfectly fine with completely manual control over the A/C system, I'm OCD about only running it when it's efficient anyways, never on acceleration, and if need be I can manually cycle it when idling too, though it should be just fine at idle.

http://www.flickr.com/photos/39006821@N03/3586317356/in/photostream/#/

So I need to check pin B8 to see if the ECM is getting the signal from the A/C system to know it is supposed to even be on. What a stupid system...

I tried a direct by-pass of the ECM circuit, which did bypass the relay, and it worked just fine with the engine off, but with the engine running it blew fuses, so I'm going to wire in a relay.

The computer actually is equipped to sense when the A\C clutch is engaged, so when I was manually jumping off the battery to test ECM compatibility it was able to detect the A\C was on and compensate, so there is no reason to have the A\C controlled by the ECM as well. Switching to full manual control tomorrow, just need to get a relay, I know I have about a dozen 30A relays, just have no idea where they actually are.

Fixed it. I basically just used a wire to bypass the entire ECM and relay and dropped to a 20A fuse to ensure I don't burn out the 16Gwiring used and it works just fine. The computer compensates for the idle just fine just by TPS and tach signal. The previous stint didn't work for unknown reasons, however I moved the wire directly into the connector instead of into the wire about a foot prior to the connector, and it just works. It's FM technology at work.