AC Compressor, how to jump out

[rballer]

New to me 2004 Z4 E85 3.0. The air conditioner was blowing tepid when i first got it. I put gages on the system and it showed low. Had the refrigerant pumped down, then went home and pulled a vacuum on the system for a few hours and it has been holding under vacuum for a few days so no leak. I've never owned a BMW so not sure how to override the low pressure switch (or whatever relay) that controls staging the compressor on to attempt to refill. Any input?

 

[Pondy]

Either your low side gauge is not calibrated or you ain't pulling a decent vacuum. Your gauge should be hard against the '30 inches' stop to be getting anywhere near a decent vacuum. 15 inches is nowhere near enough.

As for refilling, it should be weighed in from the high side (as a liquid) so the low pressure switch shouldn't be an issue. Unless you really know what you are doing, it is almost impossible to get the correct charge from filling with vapour via the low side.

I am presuming you are in the US, as unless you have a relevant qualification in the UK it is against the law to touch refrigerants (or even put a set of gauges on).

 

[rballer]

Yes. Im in the US and yes, we are allowed to work on our own cars, at will.

 

[rballer]

Advice from another forum....while under vacuum, used the negative pressure to fill refrigerant from the manifold to get the compressor to engage. $10 bux spent, back to ice cold air.....in case someone else gets stuck.

Its a shame hobbyist cant work on their own systems across the pond. Seems restrictive.

 

[Pondy]

Its a shame hobbyist cant work on their own systems across the pond. Seems restrictive.

It's all down to refrigerants being deemed as a threat to 'global warming'.
Europe has gone nuts on it now. In the UK it was not a problem for years, then suddenly they legislated to clamp down on refrigerant usage by non-qualified people.

To be honest, though, refrigerants shouldn't be used by people with no clue how to use them. They are very dangerous if handled incorrectly.

We cannot buy R134a (or any refrigerant) unless we have an f-gas qualification and are registered to buy it.

Just for information; there are people selling 'R134a' in small canisters online in the UK, but it is NOT R134a. It is a 'substitute' (we call them 'drop-in' replacements in the industry) to get around the laws and does not contain the correct chemicals so is potentially harmful to your A/C system.