Interactive 3D Hookup Lab

How to hook up a recovery machine

This page is the physical hookup of a self-contained recovery job — which hose goes where, which way refrigerant travels, and why the cylinder sits on a scale. For the rules either side of it, see recover, recycle and reclaim, the required evacuation levels, and the liquid-then-vapor sequence.

Safety: Exam-prep material, not service instructions. Refrigerant work involves high pressure, electrical, burn, frostbite, and asphyxiation hazards. Follow the equipment manufacturer’s instructions, applicable codes, and your training. Terms

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Component Lab

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Guided refrigerant path Follow the refrigerant

Step 1

Appliance Ports

Refrigerant begins its path exiting the appliance ports.

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3D View: Orbit or pinch to rotate and zoom. Select parts to learn more.

PortSuction Port Suction - Low side

The suction service port is the larger of the two ports on this outdoor unit — low side. The blue hose lands here. Refrigerant leaves the appliance toward the manifold from this port and from the liquid port.

Exam: suction = low side = blue = larger port on this model.

Hookup Parts

PortSuction: The suction service port is the **larger** of the two ports on this outdoor unit — low side. The blue hose lands here. Refrigerant leaves the appliance toward the manifold from this port and from the liquid port. **Exam:** suction = low side = blue = larger port on this model.
PortLiquid: The liquid service port is the **smaller** port — high side. The red hose lands here. This is the appliance liquid-line service valve, not the recovery-cylinder liquid valve. **Exam:** liquid/discharge port = high side = red.
Manifold: The manifold is the gauge set between the appliance service ports and the recovery machine. Blue hose on the low-side port, red on the high-side port, yellow center hose out to the machine inlet. It routes flow; it does not recover or store refrigerant. **Exam:** hose colors and which port is which — not “the manifold is the recovery machine.”
HoseBlue: Blue is the low-side hose: **PortSuction → manifold**. Use low-loss fittings on the hose ends so disconnecting does not dump the hose charge. It is not the high-side hose. **Exam:** blue = low side (suction). 40 CFR 82.152 (low-loss fitting); 82.158 requires low-loss fittings on certified recovery equipment hoses.
HoseRed: Red is the high-side hose: **PortLiquid → manifold**. Same low-loss fittings. It is not the low-side hose. **Exam:** red = high side (liquid/discharge).
HoseYellow: Yellow is the center/utility hose from the manifold to the recovery machine **INLET**. Refrigerant leaves the appliance this way and enters the machine; it does not run from the machine outlet back to the appliance. Putting yellow on the outlet is the usual reverse-hookup miss. **Exam:** yellow = center hose, and it feeds the **inlet**.
RecoveryMachine: This model is **self-contained** recovery equipment: it has its own compressor. It pulls from the **INLET** and discharges out the **OUTLET**. **System-dependent** equipment is the other type (appliance provides the push) — see Type I, not this page. **Exam:** self-contained vs system-dependent (40 CFR 82.152). Machines manufactured or imported on or after November 15, 1993 must be certified by an EPA-approved testing organization (40 CFR 82.158). Use the machine as the manufacturer directs unless that conflicts with Subpart F (40 CFR 82.156(g)).
MachineInlet: The inlet is where refrigerant from the **appliance** enters the recovery machine. The yellow hose from the manifold lands here. The cylinder does not feed the inlet. **Exam:** appliance → machine inlet. Reverse is a trap.
MachineOutlet: The outlet is where the machine sends refrigerant to the **recovery cylinder**. The outlet hose goes to the cylinder, never back to the appliance. Swap inlet and outlet and the machine cannot recover as designed. **Exam:** machine outlet → cylinder.
HoseToCylinder: This hose runs from the machine **OUTLET** to the recovery cylinder. It is not the yellow center hose. Keep the cylinder on the scale while this hose is live. **Exam:** outlet-to-cylinder path, not inlet-to-cylinder.
RecoveryCylinder: A recovery cylinder is a **DOT-approved** refillable tank (commonly DOT 4BA/4BW), **gray body with a yellow shoulder/top** (AHRI Guideline K for nonflammable fluorocarbons). Never recover into a disposable one-trip (DOT-39) cylinder — those are for virgin refrigerant and must not be refilled. Color helps you recognize a recovery cylinder; it is not proof of approval, contents, or fill limit — read the markings. **Exam:** gray body / yellow top; DOT-approved; never a disposable.
CylinderValveVapor: Missing copy.
CylinderValveLiquid: Missing copy.
Scale: The cylinder sits on a scale so you never fill past **80 percent of rated capacity by weight**. That 80% is the common liquid-volume headspace rule, measured as a fill weight using tare; it is **not** 80% of the cylinder’s gross weight, and it is **not** the Type I 80/90 percent appliance-recovery rule. Evacuate a recovery cylinder before its first use and know its tare. **Exam:** why the scale is in the picture.

Three ways this gets hooked up wrong

Wrong: never put the cylinder hose on the machine inlet, or the yellow hose on the machine outlet. Correction: the appliance feeds the recovery machine inlet; the machine outlet feeds the cylinder. Backwards, the machine is fighting the job and can be damaged. This is a hookup question, not a vacuum-table question.
Wrong: never recover into a disposable (DOT-39) cylinder. Correction: use a DOT-approved refillable recovery cylinder. Disposable cylinders that held new refrigerant are emptied, rendered unusable, and recycled as scrap — they are not refilled. Longer “how to scrap a disposable” copy stays on Core / recover-recycle-reclaim.
Wrong: never fill past 80%, and never skip the scale. Correction: never fill past 80 percent of rated capacity by weight. Liquid has no room to expand if the cylinder is liquid-full, and hydrostatic pressure can rupture it. Use the scale, tare, and the cylinder’s permitted refrigerant mass. Do not treat “80%” here as the Type I 80/90 appliance-charge recovery target ([recovery-evacuation-levels](/recovery-evacuation-levels#small-appliance-80-90-rule)).

Check yourself

Under AHRI Guideline K, a recovery cylinder for nonflammable fluorocarbon refrigerant conventionally has which colors?

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Answer: B. grey body and yellow top.

AHRI Guideline K recommends a gray body and yellow top/collar for these recovery cylinders. Color is not proof of DOT approval or refrigerant identity; check labels, markings, ratings, and requalification. Flammable-refrigerant cylinder markings differ.

The common recovery-cylinder fill guideline limits liquid to what percentage of internal volume, subject to the applicable cylinder/refrigerant limits?

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Answer: C. 80%

The common guideline is 80% liquid volume to leave expansion space. Use the correct cylinder/refrigerant mass limit and a scale, accounting for tare weight. It is not 80% of the cylinder's gross weight.

What is a low-loss fitting and why is it needed?

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Answer: B. A manual or automatic closing fitting that limits refrigerant loss at disconnect.

A low-loss fitting closes manually or automatically to reduce refrigerant released when hoses are connected or disconnected. Use appropriate fittings and equipment practices; it does not eliminate the duty to recover refrigerant.

Independent study material; not affiliated with or endorsed by the EPA. This model is for concept learning only and does not replace manufacturer instructions, codes, training, electrical safety, PPE, or proper service practices.