7730 A/C clutch control

[Six_Shooter]

There should be no patch or anything of the sort needed.

What I'm asking about is are all of the parameters that would be set in the ECM being met, such as RPM, A/C request, etc, etc?

[RobertISaar]

91 firebird 5.7:

http://i.imgur.com/IwDVFCz.png

odd.... GM chose to have compressor operation controlled by the HVAC switch along with what looks like high and low pressure switches to shut the compressor down when necessary. the ECM only tracks the status of the compressor clutch. odd that not even a relay is used, all of the current goes through the HVAC switch.


from the sounds of it, you're going to be doing some rewiring or patching SAUJP to monitor and act upon an A/C request signal.

[34blazer]

91 firebird 5.7:

http://i.imgur.com/IwDVFCz.png

odd.... GM chose to have compressor operation controlled by the HVAC switch along with what looks like high and low pressure switches to shut the compressor down when necessary. the ECM only tracks the status of the compressor clutch. odd that not even a relay is used, all of the current goes through the HVAC switch.


from the sounds of it, you're going to be doing some rewiring or patching SAUJP to monitor and act upon an A/C request signal.

I can monitor clutch operation with the adx and it does show clutch engaged when I manually trigger the relay.

other items in the datastream are: a/c req, a/c high pressure, a/c low pressure, a/c clutch indicator, A/C First Pass with HI MPH, and A/C Disabled via HI MPH

[34blazer]

There should be no patch or anything of the sort needed.

What I'm asking about is are all of the parameters that would be set in the ECM being met, such as RPM, A/C request, etc, etc?

Ive been looking through the definition and cannot find anything that controls the A/C clutch relay. Only items that relate to A/C are for IAC, fuel(pw?), and fan.

A/C clutch relay is controlled on pin F1 with $88 and $A1, but for $8D that pin is used for the shift light.

Now i can get the clutch to engage by grounding the circuit connected to F1.