went to get the A/C fixed and upon turning on the A/C the boost gauge went to -8 while in drive at idle but in park it goes down just a bit, like -5 or -6. The dreaded SES came back on again.. :( :( :( :( :( . The ses probably is the battery cables I have yet to change but this high boost gauge while the A/C is on is that normal? I sprayed all over the engine vac lines with carb cleaner and replaced the canister hoses also, no change in idle.

It is normal to lose some vacuum with the ac on. The ac draws enough power from the motor to do that.

I don't think battery cables are the cause of your SES light. Go to Autozone they will scan your car for free if you go in and tell them you have a light like that on.


Ed

Not LOSE vacuum, but GAIN, as his symptoms show.

When the AC is on, the PCM requests a slightly higher RPM to compensate for the load, the raised RPM'* produce more vacuum when in bypass, resulting in a more negative number.

This observation is expected and correct.