ADC12 sequence then single

I'm running a sequence of conversions triggered by TmrA which throws the ADC interrupt.

I want to shut off the sequence and run a single conversion in the interrupt handler and then

re-enable the sequence. The code I have is shown below.  I can't get the single conversion to

work.  It appears to run but ADCMEM0 isn't getting updated.  Suggestions ?

void adcInit(void)

{

    ADC12CTL1 = ADC12SHP + ADC12SHS_1 + ADC12DIV_5 + ADC12SSEL_3 + ADC12CONSEQ_1;
    ADC12CTL2 = ADC12TCOFF + ADC12RES_2 + ADC12REFOUT;    // turn temp sensor off
                                                    // Resolution to 12-bit, refout on

    ADC12MCTL0 = ADC12INCH_3 + ADC12SREF_1;                // ref=2.5V, channel 0 = pressure C
    ADC12MCTL1 = ADC12INCH_2 + ADC12SREF_1;                // ref=2.5V, channel 1 = sigin
    ADC12MCTL2 = ADC12INCH_1 + ADC12SREF_1;                // ref=2.5V, channel 2 = pressure B
    ADC12MCTL3 = ADC12INCH_0 + ADC12SREF_1 + ADC12EOS ;    // ref=2.5V, channel 3 = pressure A
    ADC12IE = 0x08;

    ADC12CTL0 |= ADC12ENC;

}

#pragma vector=ADC12_VECTOR
__interrupt void ADC12ISR ()

{

    tempADC_0 = ADC12MEM0;
    tempADC_3 = ADC12MEM3;  // clear int flag


    P2OUT |= DebugPin;  // switch mux
    _delay_cycles(500);  // delay 32 uS to settle
    ADC12CTL1 &= ~ADC12CONSEQ_1; // + ~ADC12SHS_1;  // turn off sequence of conversions
    ADC12CTL0 &= ~(ADC12MSC + ADC12ENC + ADC12SC);
    ADC12CTL1 |= ADC12CSTARTADD_0;   // Use Mem0, ch2  for signal B
    ADC12CTL0 |= ADC12ENC + ADC12SC;
    while(ADC12CTL1 & ADC12BUSY);
    ADC12CTL0 &= ~(ADC12ENC + ADC12SC);
    ADC12CTL0 |= ADC12MSC;  // re-enable sequence
    ADC12CTL1 |= ADC12CONSEQ_1; // + ADC12SHS_1;

}