[RUFM5]

I drove my car after it sat for 3 days and the AC blowed hot air. I checked the pressure and it was at nearly 0 PSI. Any ideas what the main leak areas are in the E39 M5? Evaporator, expansion valve, pressure switch etc.?

 

[jt2ma71]

My schrader valve was leaking on my low side for god knows how long, i only discovered it when i noticed it when i went to do a evac and recharge because it didnt seem "cold"

Take both the caps off and spray some soapy water over the schrader valve. If you see bubbles start there.

 

[RUFM5]

My mechanic diagnosed it to be a leaking evaporator at a 13-15hr job (ouch) ...expansion valve, seals will also be changed.....What else is needed I believe the dryer should be changed?

 

[Vector57]

Well, but...

My mechanic diagnosed it to be a leaking evaporator at a 13-15hr job (ouch) ...expansion valve, seals will also be changed.....What else is needed I believe the dryer should be changed?

Before proceeding with an evaporator replacement, I would want to know exactly how they determined that the evaporator
was leaking. Without disconnecting both low and high pressure connections at the firewall, capping them off, followed with
evacuating the remainder of the system and then retesting, can this be conclusively proven. It is not probable, that just all
of a sudden, without any previous findings of the system leaking down would an evaporator be found to be the culprit.

If you elect to go with their findings, be sure to specify that they return to you all of the replaced parts and provide you with
a copy of their invoice from the supplier of the new evaporator (and have them put in writing). Call me cynical, but with your
stipulating that these conditions be written into the service agreement, before the work proceeds, their diagnosis is likely to
suddenly change. If so, bid them farewell.

I have performed maintenance/repair on hundreds of automotive HVAC systems and have yet to see symptoms, such as you
described, that turned out to be an evaporator fault.

As to your list of parts, replacement of the receiver/drier is mandatory anytime the refrigerant is totally depleted.

Regards,
Alan