Had aircon fixed when I first got the car cost me $550 to install a Relay. Changed out Engine and ECU and now the Aircon compressor won't engage again. So I unplugged the Relay the auto elec installed hoping this would fix but still no go, aircon works fine if I engage the compressor with 12v. Relay in Cabin Pic Below Pin 5 Direct to Earth Pin 3 to ECU Orange with Silver Wire (Earth when Relay engaged) Pin 2 to Control Box Behind Ecu 12V when Ignition ON Pin 1 to ECU Light Green with Silver Wire 0 volts & no Earth (think this should Have 12V when relay Energised????) AirCon Relay in Engine Bay Pin 1 & 2 12v With Ignition ON Has Earth with Ignition OFF Pin 3 No Earth No Voltage in any state Pin 5 Earth with Ignition On or OFF No Voltage
Why did he install another relay!!?!? Makes no sense to me. When you say you engage the compressor with 12v, does that mean directly to the clutch? If the gas pressure is low it will prevent the compressor engaging (if wired up properly). With your mess of new stuff we really need to know where all the wires come and go.
Ecu Chrissy Said he wasn't getting an earth signal from the ecu. Not sure why he installed another relay. Might unplug added relay and try fault finding from their any sugestion on we're to start? Answer to other question I added 12v direct to clutch.
Has the gas pressure been checked and filled up if required? That is where I would start, and after that the aircon computer in the drivers foot well on the left hand side. Most of the system is pretty simple. I don't know it inside out, but the manual has a very good trouble shooting section. From what I understand the ECU output is only for idle up etc. All actual aircon control is from the air con computer.
The ECU will influence the AC clutch as well. It disconnects the clutch on high power/high rpm conditions as a rule. E
Relays: The diagrams on the relays are shown with the relay "at rest" as it comes out of the box. In the first picture, pins 1 & 2 activate the relay, it doesn't matter which way the wires are connected, one will be +12VDC the other connects to ground (earth). Pin +3 would normally be the +12VDC supply. Pin 5 would supply +12VDC to the item to be turned on when the switch is activated. If pin 4 was connected to the item, +12VDC would be supplied constantly & would disconnect when the switch is turned on. Looking at the blue relay, pins 1 & 2 activate the relay as above. Pin 3 would be the supply (+12VDC) & pin 5 would act as above. Depending on the circuit, relays can also switch earths, so rather than supply voltage, the can provide or disconnect ground (earth).
With ignition ON, you should have 12V+ at either terminals 1 and 3 or 2 and 5. The corresponding relay terminal runs to your ECU, which grounds the circuit to operate the AC and the corresponding contact wire will run to your AC compressor clutch coil. The picture that shows those 3 x 15A fuses in a row. The MIDDLE one is for your AC. It should only be a 10A. Pull it and see if it has blown. if so, would replace it with the recommended 10A fuse and try again. If the fuse blows, would be looking at getting your compressor clutch rebuilt. Might also pay to trace the compressor clutch wire back to the harness. It can be visually located on top of the compressor and then traced back as a single wire back to the harness, almost adjacent to the relay panel, as a spade connector. Rather easy to have been broken or disconnected if any work that way has been carried out (intake pipes removed etc)
