AC Vacuum Pump and Oil

[Dynomite]

Originally Posted by VetteVet

Cliff,

Remove caps on drier and install it just prior to vacuuming the system. The hose on the left side(blue) is low side. The hose on the right side(red) is high side. If you look at the evaporator housing, the line going into the bottom is the high pressure line. Follow that one back and you will find the high side fitting. The one on the accumulator/drier is the low side fitting. Vacuum the system with both valves open. Charge the system by opening the low side valve only. This is especially important as the pressure developed when the compressor is running will rupture the can of freon. NEVER, EVER open the high side valve with the compressor running.

If you don't have one, you'll need to pick up a freon can valve from your local auto parts store.

Hook up the yellow hose to the middle connection on the gauge manifold and to the vacuum pump. Vacuum the system and then shut manifold valves first, then shut off pump. Let the sytem sit long enough to ensure that vacuum is not dropping. If it is, you have to find and fix the leak(s). If not, then diconnect the hose from the pump and hook up the can valve to the yellow hose. Prior to connecting the valve to the freon can, unscrew the valve stem fully(you will see the needle in the valve retract up into the body). Then screw the valve onto the can. Now turn the valve fully clockwise to puncture the can, then turn fully counterclockwise to open the valve. With the can upright, crack the fitting on the yellow hose where it attaches to the gauge manifold to purge the air out of the hose, then retighten it. You can now invert the can and crack the blue low side valve and charge until the pressure equalizes between the can and system(no more flow is felt or heard). Now start your car and set the climate control for Max cooling with blower on high. Ensure that the compressor clutch is engaged at this point. If not, you will have to pull the connector on the pressure cycling valve in the low side line and jumper it. The compressor clutch should now engage and you can charge the remainder of the first can with it in an upright position. Always charge with can upright when compressor is running. Once the first can is in, (you'll know it's all in when you can shake the can and not feel any liquid sloshing in it) you can shut the low side valve and swap to the second can. Remember to purge the yellow line again prior to charging. Continue this until you have added the correct amount of Freon, per the FSM. Once the sytem is fully charged, shut off the compressor and allow high and low side pressures to equalize before disconnecting the gauge manifold from the system. Once the manifold is disconnected, cap the high and low side fittings, reconnect the pressure cycling switch and you're done.

Jep

Jep....I can do this

Nice write up....appreciate it
I put all your information together in a single post if that is OK with you and if I understand the technical information correctly.......Evacuation and Re-Charging C4 ZR1 A/C System
Jep......... really appreciate you taking your time to explain this for us

I will go slow and practice vacuuming A/C and checking for leaks first. I think before I install new drier. Then vacuum the A/C system a second time after I know there are no leaks.

The 91' ZR-1 is running sooooo good it is unbelievable
With ALL the eliminated systems and with TB coolant removed LT5 Eliminated Systems.

The new technique of Eliminating Air from the coolant system worked perfectly for this refill of coolant Filling With Coolant and the Air Locked Water Pump.

Cliff