1995 Pontiac GP issues

[sboater]

I have a friend with a 95 GP 3.1 with a check engine light. I reviewed data and pulled codes and the code is 77 (EGR solenoid #3 malfunction). When looking at the data on the scanner it also shows a bad quad driver 4. Lastly, the a/c seems to be backwards. When the computer shows the a/c request on, the a/c shows disables and when the a/c request is off, the a/c shows enabled. The scanner also cannot reset the codes. I had to disconnect the battery to reset. I am wondering about a bad computer (bad egr still a possibility) as I have seen this on a chevy lumina. Any thoughts?

[richtazz]

I would say that the EGR is bad (fairly commn on the 3 solenoid design that car uses, EXPENSIVE too) and the A/C system is low on charge. IT disables the system when A/C is requested because the pressure switch is detecting low system pressure. It shows the system enabled when A/C request is off because it isn't reading the low pressure switch signal, so at that point, it doesn't know the system is low. A bad computer will normally show no codes and will cause intermittent hesitations, stalling and loss of injector pulse among other things.