944 Air Conditioning — Technical Data, Refrigerant & Service
Factory data for the 944's R12 air-conditioning system — the refrigerant charge, the compressor oil fill, the rupture-seal and coupling-power figures, and the compressor/condenser/line tightening torques — followed by a concise evacuate → flush → charge service overview with its vacuum and pressure targets. This is an R12 system, so handle the refrigerant only with proper recovery equipment. Pressures switch between bar and psi and torques between N·m and ft·lb.
Factory data for the 944's air-conditioning system, revised on the 85/2 model so that the evaporator sits together with the heat exchanger in one housing and cabin temperature is held automatically. This page collects the charge, oil and torque figures alongside the service sequence used to open, evacuate and recharge the system. For how the controls work and for symptom-by-symptom diagnosis, see 944 HVAC operation and malfunctions and air-conditioning troubleshooting and repair.
The compressor coupling is dimensionless electrical power and is written as-is; the refrigerant charge and oil fill are given by mass and volume and do not switch units; the rupture-seal and service pressures switch between bar and psi, and the tightening torques between N·m and ft·lb.
Warning: This is an R12 system. R12 must be recovered into approved recycling equipment — never vented to atmosphere. It boils well below room temperature: liquid R12 on skin causes frostbite and in the eyes can cause blindness, so wear goggles and gloves. A charged component holds very high pressure; never apply heat or flame to a full circuit. Keep refrigerant bottles out of direct sun and never drop or throw them.
Technical data
| Item | Specification |
|---|---|
| Refrigerant | R12 |
| Refrigerant capacity | 950 g |
| Compressor (refrigerator) oil | Densoil, 60 cm³ to 100 cm³ (80 cm³ nominal) |
| Rupture seal on fluid reservoir | fusible element opens at approximately 30 bar435 psi overpressure |
| Compressor coupling power consumption | approximately 40 W |
The compressor oil fill is nominally 80 cm³ with a 20 cm³ tolerance either side. The fluid reservoir carries a fusible rupture seal that relieves the circuit if pressure climbs to about 30 bar435 psi — a protection against overheating, not a service setpoint.
Tightening torques
| Location | Fastener | Thread | Torque |
|---|---|---|---|
| Compressor | hex bolt | M8 | 28 N·m21 ft·lb |
| Evaporator | hex bolt | M6 | 6 N·m4 ft·lb |
| Fluid reservoir | union nut | 5/8" × 18 UNF | 17 N·m13 ft·lb |
| Condenser intake | union nut | 11/16" × 14 UNF | 44 N·m32 ft·lb |
| Condenser outlet | union nut | 5/8" × 18 UNF | 17 N·m13 ft·lb |
The union-nut sizes are refrigerant-line thread codes and are written as-is; only the torque column switches between N·m and ft·lb.
Service overview: evacuate → flush → charge
Opening the refrigerant circuit for any repair means recovering the charge, drying the system under vacuum, flushing it, evacuating again, then recharging with the correct mass of R12. The sequence below follows the factory service unit; the valve numbers refer to that unit's own controls.
Recover the charge
Extract the R12 into approved recovery equipment before disconnecting anything — never vent it. Before extraction, check the fluid-reservoir sight glass: brown discolouration inside means the refrigerant should be drawn out only through the high-pressure side, through a clean-up drier fitted in the extraction hose.
Evacuate
- Connect the service unit and extract the refrigerant.
- Switch on the vacuum pump and open the low-pressure, high-pressure, torr-meter and evacuating valves.
- Run the pump for at least 15 minutes.
- At approximately 0.1 bar1 psi absolute, close the evacuating valve and — importantly — the torr-meter cutoff valve, so the torr-meter is not destroyed in the flush that follows.
- Switch off the pump.
Caution: If the vacuum is unreachable, takes a very long time, or the pressure climbs back above about 0.2 bar3 psi absolute within roughly 10 minutes of stopping the pump, the circuit is leaking. Find and seal the leak before going any further — a leak-down check is the go/no-go gate for the rest of the job.
Flush
With the system evacuated, open the filling valve and the high-pressure valve and let liquid R12 flow in until about 2 bar29 psi absolute is indicated. The refrigerant vaporises inside the system and carries off any traces of moisture. Then extract the refrigerant again and evacuate once more. A pressure rise of 1 bar15 psi takes roughly 10 minutes, so allow time for the flush to work rather than rushing the gauge.
Charge
- The system must already have been evacuated, flushed, evacuated a second time and proven leak-free.
- Close all service-unit valves and confirm the filling cylinder holds enough R12; top it up if not.
- Bring the filling cylinder to about 7 bar102 psi positive pressure by switching on its heater, then set the required refrigerant quantity on the cylinder's sliding scale — using only the R12 scale, as the cylinder is marked for several refrigerants.
- Re-check that every valve, especially the torr-meter cutoff, is closed, then open the filling and high-pressure valves and watch the sight glass; when the liquid level reaches the setting ring, close the filling valve.
- Switch off the cylinder heater, disconnect the fill hoses from the compressor and fit the protective caps.
If gas bubbles are still visible in the fluid-reservoir sight glass with the system running, the charge is short. Top up rather than draining: rectify any leak, then with the engine at about 2000 rpm and the A/C switched on, add refrigerant on the low-pressure side until the bubbling in the sight glass stops.
Caution: While the compressor is running, the high-pressure and low-pressure service valves must never be opened at the same time.