mj1pate

Being a newbies guide, corrections by the experienced can only help. This person has done this (recently) once. It is possible to charge with small cans without introducing air. And in the process of doing this, you can visualize how a distracted tech could incrementally leak air into the system while charging. This guide is a reflection of the experience from performing it once.

Phase 1:
***AC System Pre-Charging ***

Collect Parts:

Vent thermometer

Scale

Shop glasses

Nitril gloves

Refrigerant tap

36 oz refrigerant

10 oz oil should already have been added



Note: Do NOT consider adding oil via the manifold input hose. Firstly the hose holds maybe an ounce. Secondly, you won’t be able to purge any air from the input hose without burping out all the oil. There are better ways to add oil post-charge.


Actions:

-put sticky on closed off manifold HP valve, “Don’t Touch”

-pre-enable rear ac air and refrigerant flow: turn rear cold dial to full cold

-place a temp thermometer into vent



** AC System Charging Process ***

Maintain Vacuum integrity:

-Ensure manifold valves both closed

-disconnect manifold input hose from vacuum pump



Tap First Refrigerant can:

-add Tap to refrigerant can

-connect manifold input hose to tap

-tap into first refrigerant can

-keep tap closed



Purge System:

Open up can tap

Press manifold input hose schrader valve to purge air



Start charging — first can:

-start car

-press AC button

-switch AC jumper to “on”

-open ONLY low pressure manifold dial SLOWLY

-place can in cool place

-observe compressor should start

—low pressure reading should lower

— high pressure reading should increase

— May need to twist tap handle back and forth a bit to keep maintain flow

-can empty? Shake it and watch manifold glass to make sure

-really empty?

— close off manifold low pressure dial

— close off tap on can

— remove tap from can, with hose still attached



Second can:

• tap should have its twist valve retracted, preventing any flow and hose still attached
• twist tap (hose still attached) onto new can
• Twist tap’s valve to allow flow
• Open manifold low pressure valve SLOWLY
• -can empty? Shake it and watch manifold glass to make sure
• -really empty?
• — close off manifold low pressure dial
• — close off tap on can
• —remove tap from can, with hose still attached

Third Can:

• tap should have its valve retracted preventing flow and hose still attached
• twist tap (hose still attached) onto new can
• Twist tap’s valve to allow flow
• Open manifold low pressure valve SLOWLY
• -can empty? Shake it and watch manifold glass to make sure
• -really empty?
• — close off manifold low pressure dial
• — close off tap on can
• —remove tap from can, with hose still attached

Remove Manifold Gear:

-ensure BOTH manifold gauge dials are closed

HIGH SIDE:

-shut off High Side gauge hose at the drier

-remove High Side gauge hose from drier

-remove 134/12 adaptor from drier schrader valve

LOW SIDE:

-shut off Low Side gauge hose near the fender

-remove Low Side gauge hose

-remove 134/12 adaptor from schrader



Close Out:

Add caps to schrader valves

Check vent temp


Soliciting Comments: Do you prefer to leave your 134/12 adapters on the High Pressure/Suction schraders, or remove the adapters after charging?
Or maybe de-core the schraders and leave R134 adapters attached?

mj1pate

Some additional notes:
When beginning the charge, I could NOT hear the compressor clutch engage due to open-hood engine noise. I realized the compressor clutch had engaged once the high pressure gauge began increasing and the low pressure gauge began falling.
When engaging the clutch engine-off, the clutch was audible when it engaged, but not the monster clap clutch engaging noise I some times hear from other vehicles. That may be due to typically smaller engines with less engine noise.

Also, the ambient was around 80 degrees. Fully charged, in the shade, HP side read 240 psi, low side around 45. Vent temp was 42 degrees. Engine temp was slightly below the first gauge hash mark.

And to add yet another note: vacuum and test pressure leaks were resolved via a rental ultra sonic leak detector. It’s less likely the leak detector will be necessary going forward, since the ester oil was impregnated with fluorescent dye. Confidence is truly high that the UV light will locate leaks because…well I’ve learned that oil glows so much in plain daylight, I wonder if it’s radio active.

Jason89s4

Can you be more specific on when and how the vacuum pump is used?
Before charging? Only after the system waas opened ( ie. after replacing o-rings or a new drier)
In other words how do you utilize a vacuum pump in all this?
Thanks, Jason

StratfordShark

What’s that ‘AC jumper’ you refer to? Are you jumping the LP switch or something else?

Thanks for detailed write-up. Working with gauges it’s easy to inadvertently open a valve at manifold or at high and low pressure ports at wrong time!

mj1pate

oh Sorry. My AC head relay is out. There is continuity between the AC head “violet” output lead and the anti-freeze switch, which is still good. I had to jumper 12v battery post to the input of the anti-freeze switch and the AC clutch would engage, once the engine was running and refrigerant charge started.
My FIRST time doing refrigerant charge after full flush, replacing all the orings and bench testing components I could.
No I did not trust myself to do a very task oriented refrigerant charge without poisoning the manifold HP valve (“NO!” Sticky) and having a prepared script for every step.

mj1pate

the process of preparing to revivify the long dead corpse of my AC system took about a year.
a much more recent condenser and compressor (thanks Kevin!) helped. Applying the JB weld to the copper pipe junctions of the the rear evaporator and minor adjustments to get the rear resistor pack operating all took their time.
after reassembling everything the system needs to be placed under vacuum (for 6 hours), then measured making sure it held 30” vacuum for 24 hours. We also need to measure pressure holding capacity. I used extra dry air (110 psi) with a sacrificial drier.
then because we have dye in our oil, we trace leaks post charge

StratfordShark

Got it, thanks. Is head relay available for your MY or will you rig one external to the board?