A/C not working

ELI0319

MEMBER
2003 NISSAN XTERRA
3.3L
V6
2WD
AUTOMATIC
127,000 MILES

I’ve changed my A/C compressor and condenser vacuumed the system recharged at 25 oz with direct current to compressor so it kicks in. Then I thought I was done but compressor won’t engage. Replaced the relay nothing. I closed the circuit of the relay with a piece of wire and compressor engaged A/C button on dash lights up. I can’t find what’s wrong. Any ideas? Also, my good sir would you please help me with the wiring A/C schematics? Thanks for your help and time.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Okay. So if you are jumping the relay and it comes on, that proves out wiring and the thermal switch. So now we need to check the ECM's ability to ground the relay.

Take a look at the wiring diagram and remove the relay. Put your test light clip on battery positive because we are testing the low side driver of the PCM. Then touch the terminal with the pink wire coming from the PCM with your probe and turn the AC on. Does the test light come on? If it does then the PCM is grounding the relay. However, I suspect it will not.

If it does not come on then your PCM is not grounding the relay to turn the A/C on. This may be due to the pressure switch. So you want to go to the switch and check for power coming out on the green red wire which tells the PCM that the pressure is not to hi or low. If this switch is open then the PCM will not ground the relay.

If the switch is okay the PCM is the issue. If the switch seems to be the issue, jump the two terminals with a paper clip with the relay back in and see if the compressor comes on.

Let me know what questions you have. Thanks

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