1986 Fiero, V6 Manual was converted to 134a, by me, in September 2020.

The system is sealed and holding a charge, however, slightly over charged.

The compressor does not activate when I turn the AC on.

New fuel pump and AC relays, fuses checked and are good

I jumped the wires at the accumulator, and the compressor did not activate. There is about 10 volts reading between the two wires (with engine running and AC on)

I tapped into the electrical line to the compressor, 12 VDC, with the engine running, AC on, the compressor activates, cold air from the AC.

Issue: Jumping the wires at the accumulator does not activate compressor, engine running, AC on
Issue: Running 12 VDC directly to compressor, engine running, AC on activates the compressor, cold air

Note: After converting to 134a, AC did not come on as expected, I had to run 12 VDC to the compressor. The engine stalled, seemingly as the drag on the engine after activating the compressor caused the engine to stall. After a few tries, the compressor seemed to suck oil through and worked just fine with the engine running, cold AC, but, again, the compressor does not perform as the AC system is designed to operate by simply turning it on, wires connected to accumulator.

No voltage reading at the compressor wire with system on, engine running.

Anyone know what my fix is?

I've tried to jump the terminals on the low pressure switch on the accumulator and not have it work, either... Issue is that sometimes the connection when jumping is finicky and you gotta squeeze the paperclip you're using as a jumper to hit the terminals in that connector in such a way for it to make the connection.

-When you did the R132 conversion, did you change the pressure on the Low Pressure Switch by calibrating it with the screw, or did you replace it with a new one that was already set?

-Overcharged? I hope you don't mean overcharged in more than the amount the sticker says it needs in an R-12 charge... You're supposed to put about 20% less R134 in with the conversion.

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I will re-test with the jumper at the accumulator.

I did not adjust the new pressure switch. Tell me more about how to do this. I do see the screw, however have never known how to adjust it. Please share.

The fill was done with instructions from the online discussions, and from the recommended instructions from EZ Chill.

Right now, today, October 18, the charge is holding, when I jump the compressor with 12 VDC, it activates, and I get cold air. Not just cool air. It feels like you open your freezer on a hot day.

So, my take-away from your response is the following:

1) Re-test the jumper at the accumulator
2) Confirm refrigerant level

If there is anything else that you know that might be a fix, please share - thanks

If you jumper the connector at the accumulator, and nothing happens, adjusting the switch will not change anything.

There is a high pressure switch on the back of the compressor. If that switch is bad (or has a bad connection) it could cause your compressor to not kick on.
(Too much refrigerant will not cause the switch to trip. It isn't supposed to activate until it reaches several hundred lbs.)
I believe the high pressure switch is "normally closed". Too much pressure will cause it to open (switch off) and drop the signal to the compressor clutch.

...or you may just have a bad A/C relay. It's on the firewall, behind the driver, right next to the fuel pump relay. (I forget which is which.)

[This message has been edited by Raydar (edited 10-18-2020).]

I went under to look at the compressor to confirm the high pressure switch is on the back of the compressor. There is no other connector/connections on the back of the compressor. I only have the two wire connector that connects just behind the equipment belt on the compressor.

If there aren't any connections on the back of the compressor, then the compressor ought to run, just by default.
Check the relay up at the top, up near the fuel pump relay. If that's good, you might have to dig deeper.

Edit -
Wait... Where did that compressor come from? The stock compressor has two switches.
That being the case, you should have the connectors for those switches, hanging behind the compressor, someplace.
You should be able to jumper one of those connectors to ground (I think the small "pin" connector) and the compressor should work.
You need to add that switch (at least the high pressure switch) and the appropriate connector, to protect your system.

Sorry. See the post below.

[This message has been edited by Raydar (edited 10-23-2020).]

I just did my AC in September but on a 4. If you do not have the high pressure plugged in or jumped to gound (v6 the high switch is the ground for the clutch) the compressor will not kick on. You can jump out the power at the relay to test this. Blk/wht to dk grn. I think its the side pin to the center pin


My ac relay plug was gross needed tons of cleaning.

[This message has been edited by skywurz (edited 10-22-2020).]