A/C not turning on for testing

[M Blitz]

Ladies and Gentlemen,

I have not added R-134 to the A/C system yet after doing an engine swap. With the ignition "on," the A/C switch won't light up when I push it, there is no voltage at the connector, and the clutch won't "click."

Is this part of a fail safe and once I put R-134 it should work?

Thanks.

[Mike W.]

No, unlike most cars and even newer BMWs, there is no low side switch to inhibit the compressor from turning on if it's low on charge.

[M Blitz]

Thank you Mike; much appreciated.

[ccchrisss]

This happened to me intermittently, try lightly cleaning/sanding the contacts for the fuse and swapping or cleaning the fuse itself.

[vinceg101]

There is a large relay under the dash (driver's side, just above the accelerator pedal, next to the HVAC box) that controls the compressor.
It does go bad and/or it got fried accidentally, so it might be the culprit.

Be sure you get the correct one, the one that you want (and works) has the shiny reflective mirrorized sticker:


They're expensive: https://www.pelicanparts.com/More_Info/ ... 4501376710
So maybe try ebay, I think that is where I found the one in the photo above.

[Ohmess]

This relay can't cause a lack of power at the A/C switch. A/C switch sends power to energize the relay; relay then sends power to the compressor from the other side of the relay. If that relay is bad, the compressor won't run, but there will still be power at the A/C switch.

Where exactly don't you have power? In my car, power comes into terminal 5 on the switch directly from fuse 14. If you don't have power here, its likely a fuse or a wiring problem.