A/C without an ECU in an S13?

[JrDarknes]

You kind of need to reword a few things on your second paragraph but I get what you're asking & you're correct. You will need another relay to control those relays. It will be a ground based relay.

Your talking about terminal 43 on relay 1 (A/C Relay) and terminal 47 on relay 2 (condenser relay).

Both of those terminals are ground based. So this means that when you click the A/C button on your climate control it grounds at the climate control and triggers those relays to activate.

So to make both of those relays work you just need to make a relay that triggers a ground signal and wire them to terminals 43 on relay 1 and terminal 47 on relay 2. One issue with this though is that you kind of need sometype of ECU for your thermo control amp.

The thermo control amp senses the evaporator’s temperature via a temperature sensing probe that is located in front of the evaporator core. The thermo control amp will then inform the ECU whether to cycle the compressor magnetic A/C relay ON or OFF.


You can try to use the ground relay without the thermo control amp but there a chance you could freeze up the evaporator.