REFERENCE · LIVE
A7 Service Procedure Card
3-phase A/C service done correctly: recovery, evacuation, and charging — with pass criteria, common mistakes, and ballpark charge weights for common platforms.
UNIVERSAL RULES
- Identify refrigerant type before connecting recovery (R-134a, R-1234yf, R-744, or contaminated).
- EPA Section 609 cert required for refrigerant work in the US.
- Never vent refrigerant. Federal violation + fine.
- Never pressurize with oxygen or shop air — use OFN (oxygen-free nitrogen) only.
- Always charge by exact factory weight. Gauges and "sounds right" are not accurate.
PHASE 1
Recover
15-30 min · machine + scale
- ID refrigerant type
- Connect machine, open valves
- Run cycle until system at ≤ 0 psi for 5 min
- Weigh recovered refrigerant for invoicing
PASS
Machine signals complete; system holds at slight vacuum
PHASE 2
Evacuate
30-45 min + 15 min hold
- Connect 2-stage vacuum pump and micron gauge
- Pull vacuum to ≤ 500 microns
- Close manifold valves to isolate pump
- Hold 15 min; watch micron gauge
PASS
Rise ≤ 1000 microns over 15 min hold
PHASE 3
Charge
10-15 min · scale required
- Read OE underhood charge spec
- Place tank on calibrated scale
- Open HIGH side; vacuum draws liquid
- Close at exact target weight
- Start engine, verify pressures + vent temp
PASS
Pressures stabilize for ambient; vent ≤ 50°F at idle, max A/C
Common Charge Weight Reference
Always verify against underhood label — these are typical ranges only.
Compact car (Civic, Corolla)
R-1234yf newer / R-134a older
14-18 oz
Midsize sedan (Camry, Accord)
16-22 oz
Compact CUV (RAV4, CR-V)
17-22 oz
Midsize SUV (Pilot, Highlander)
22-30 oz
Full-size truck (F-150, Silverado)
28-36 oz
Heavy-duty truck (F-250, Ram 2500)
30-44 oz
Full-size SUV (Tahoe, Expedition)
28-38 oz
Rear-A/C equipped (minivans, full SUV w/ rear A/C)
40-58 oz
CRITICAL FAIL POINTS
Skip these at your own risk
- Short evac (15 min): Moisture stays in. Forms acid with oil. Compressor failure in months.
- No vacuum hold test: Undetected leak. Customer comes back next month.
- Eyeball charge: Over/undercharge by 20%. Performance complaints or compressor damage.
- Mixed refrigerants: Recovery tank contamination. Whole tank scrapped. Customer pays.
- Oxygen pressurization: Explosion risk. Use nitrogen only.
- Skipping drier replacement after open: Moisture saturates desiccant. Replace drier any time system is open more than 15 min.