Holden VS Aircon Master Bypass switch

[tavrin]

Hey Guys,

This is my first time posting - so I do apologise if i’m posting in the wrong section.

DISCLAIMER: This is a guide only. By following anything described here, I take no absolutely no responsibility what-so-ever. If you somehow stuff it up, fry your ECU, blow up your A/C compressor or somehow cause your car to eat you up; you do so at your own risk.

Anyway, with the warmer weather slowly moving in - my friend asked me today if it was possible to make an Air con Bypass switch which essentially engages the Air con clutch independent of the Air con’s Thermostat. The idea is really simple. All you need to do is provide a 12v source to the primary side of the A/C relay to engage the A/C compressor and tell the ECU that the A/C is operating so that it will increase the idle revs and turn on the thermo fan accordingly.

For now I’ll upload the wiring diagram necessary to undertake this mod. I'll hopefully gather more pictures of everything wired up later this week.

Note - While I did say you only require a 12v source to engage the clutch on the A/C, a more appropriate way of obtaining this source is to tap the 12v from the A/C switch instead. This is because if you take any 12v source, if you somehow forget to turn off the master bypass switch - the clutch will STILL be engaged even though your fans are turned off! [epic disaster]!!!!!!!

Cheers.

 

[bcw61]

I am curious why you didn't simply connect the override switch directly across the A/C thermostat switch (G/Y to BR wires), as it would keep the A/C pressure switch in the circuit and provide protection for the A/C system that it was designed to do.

Your circuit takes the A/C pressure switch out of the circuit when you select override. If the system has a malfunction that the A/C pressure switch normally protected against, then you might risk damaging the system.

 

[BowTie]

Delete your aircon.


Go on.

 

[tavrin]

Oh my appologies, I thought I updated this thread with the updated version months ago. Yeah your right bcw61 - Im pretty sure I ended up rigging it similar to how you suggested a few days after uploading that diagram above.

 

[VR38]

What is the advantage?

 

[Cosmosis]

Why exactly would you want to remove the pressure switch from the circuit?

if gas were to leak from the system the compressor will still be engaged. - No Gas= No flow of oil, leading to a f***ed copmpresssor. Another scenario, the TX valve jams, and pressure on the high side goes right over, the compressor will not cycle out, pressure goes through the roof, could blow a hose, damage the compressor and other A/C components.

Seems like a pointless mod to me. If the A/C system is not working, theres obviously a reason for it. Get it checked out by a QUALIFIED A/C SPECIALIST!