Auto Air Conditioning & Heater Repair: Clutch will not engage, test light, pink wire

Question
Ok it is a 94 firebird v8 AC not working the clutch will not engage all fues an relays are ok. But the relay has 4 wires 2 green that are hot an 2 pink that are not if I take a test light an put in on the pink wire the clutch will engage. I am lost help me if you can thanks

Answer
Do NOT go probing these low voltage wires with a test light. You WILL fry the vehicles computer as most of these sensors operate on 5 volts and will not tolerate a 12 volt test light as it over draws the voltage output of the computer transistors.

I can't stress this enough. Put that test light away.


I do NOT recall saying anything about testing a RELAY. The contact that you touched with your test light is on side of the ground side circuit of the relay which is controlled by the vehicles computer. I hope you did not fry this circuit using this test light.

You could have a problem with the TP, ECT, IAT Refrigerant pressure sensor, ECM Or the relay. Most of these sensors operate on a 5 volt signal and all must be properly tested using LOW VOLTAGE test equipment.

There are so many possibilities that it is impossible to tell which sensor is at fault or what is the problem without performing numerous tests.


Now we have the worry about you may have caused another problem with the computer with your test light.


Your pretty well stuck to take it into a professional facility for diagnosis and be SURE to tell him about your TEST LIGHT test so he can check that circuit.



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