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Join Date: Apr 2016
Location: Norf TexASS
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Will try to keep nasty commentary out of vac and charge procedures post so not to make it more difficult and confusing to read than it will be all on its own.

Evacuation Procedure


*** Am presuming you already have the proper amount of ester oil (like A/C Pro, 765-3510 / medium viscosity Ester with ICE32) in the system?

1) Lightly lubricate service port fittings - I use silicone grease, but some refrigerant oil will work fine.

2) Attach manifold hoses to system service ports (red to highside/dischrage and blue to lowside/suctiion) but leave the taps on the gauge manifold and hose ends in the closed position. Attach yellow manifold hose to vacuum pump.

- Turn pump on, open manifold taps and service port fitting taps (turn those gently so as not to damage the Shrader valves in the service ports) . . . both high and low sides opened for this.

- Observe that the high side gauge reads zero, and that the lowside gauge quickly drops to negative 29-30. If this does not happen, then you have a big leak in the system and need to investigate.

- Allow pump to run one hour and then close the manifold valves (leave service port valves open), and then turn the pump off. Allow system to "rest" for a half hour (the industry standard time) and if no change in pressure (a vac pressure loss of a psi or two is acceptable in order to account for hose expansion/contraction and changes in temperature, but you probably won't see any movement of the gauge needle.) forge ahead. If vac does not hold, you'll have to start leak troubleshooting.

- Following successful vac holding test, turn pump back on, re-open manifold valves and allow the pump to run for an additional 2-3 hours. That might seem like and excessive amount of time, but given the amount of hose in a 911 a/c system, and how the components are spread throughout the car, that amount of time on the pump ensures that all moisture will be removed from every nook and cranny.

- At conclusion of vac time, shut the service port valves, shut the manifold valves, turn off the vac pump and disconnect the yellow hose from it (keep the other hoses attached to the service ports). NOTE - do not turn the service port taps or the manifold taps after pump is off or the system vacuum will be ruined and you will have to start over. NOTE number two - if proceeding to charge immediately following vacuum pull (a good idea) then do not need to shut the service port taps - only shut the manifold taps.


*** will type charging procedure this evening, bisch - will add it to this post***

Last edited by Rawknees'Turbo; 09-19-2017 at 08:19 PM..
Old 05-25-2017, 09:53 AM
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