850 climate control troubleshooting

1. Power OFF, pressure switch connector disconnected. 2. Measure resistance between pressure switch terminals — should be 0 ohms. 3. If not, proceed to further tests. 4. Pressure switch connector disconnected, engine running, A/C ON, blower ON. 5. Measure voltage between incoming connector pin 1 (green wire) and ground — should be battery voltage.

Check pressure on low-pressure side (blue): Below 320 kPa: charge with 500 g R134a (power OFF) Above 320 kPa: proceed to electrical testing Electrical test: power OFF, measure resistance between pressure switch connector pin 2 (gray wire) and ground. Below 5 ohms = proceed to compressor circuit test.