GEN 1 viper A/C idle too low, help

[THEMASH]

A friend of mine has installed an aftermarket A/C (not from the factory) in his 1993 RT10. at idle, the RPM dropped to 500 with the A/C.

Is there anyway to increase the idle/fix this problem? he told me he tried everything but nothing is working. He is overseas so he cant really take it to a Vipertech.

Any help would be great

 

[Jeff Torrey]

I would call Sean Roe and as him if the Vec II could adjust the idle control, My guess is yes.

 

[Tom F&L GoR]

If he installed the A/C he has the guts to try this:

Find a vacuum hose ****** and introduce an air leak around the idle air control valve. The PCM may decrease the IAC valve opening to get the speed back down, so it may require some fooling around. If the idle speed can be raised satisfactorily this way, perhaps using a valve to adjust the idle speed (look for brass aquarium valves?) then a small electric solenoid can be used and powered via the same wire as the A/C clutch. So whenever the clutch is on, the new air flow solenoid is on, passing extra air through the hand-calibrated fish tank valve.

I'm assuming that the PCM doesn't have A/C capability (i.e. Pin 34 on the PCM does not have 12V output when the dash A/C knob is "on.") If it does, then did the installation provide some signal to the PCM to let it know the A/C is on? (input to pin #27 for PCM?)

Another way to increase idle, I think, is to fool the engine into thinking it's cold. I don't know if this affects idle, but perhaps disconnecting the engine coolant temperature sensor would do it. Then again, when AC clutch gets power, the sensor reading is disconnected. Probably cause an unhappy PCM and start a diagnostic code, but given it's a '93, may not be an issue. There is a sensor for the PCM (pin 2) and another for the gauge, so this will not affect the cockpit reading.

Love these kinds of projects...

 

[Gerald]

What about a PCM from a GenI that has factory A/C ?

Gerald

 

[GTS Dean]

None of the '93s had factory AC. Mine was dealer-installed, but I don't remember anything about having to reflash the PCM to make it work. However, it's been nearly 12 years since I bought that car, so I don't remember much (technical) about it anyway.

 

[Gerald]

Would a PCM from a 94 work that had factory A/C?

 

[THEMASH]

Thanks for the help guys, i will forward the info to him.
by the way, i found out its a 94 not a 93, but with no A/C. i thought all 94s had A/C. his did not, its an import, which might be the reason.

Thanks again