A Clutch Is Two Interfaces — Bus Air Conditioning Compressor Magnetic Clutches

1. The Same Clutch Fails for Two Completely Different Reasons

A magnetic clutch has an electrical interface and a mechanical interface, and they fail independently. A burnt coil and a worn pulley groove are different faults with different symptoms — and when a clutch is bought by the wrong dimension, it is almost always one of these two that was mismatched.

So this page splits the range the same way. Read section 2 for the electrical side, section 3 for the mechanical side. Most buyers only need one of them.

Symptom guide. Compressor does not engage at all → start at the electrical side. Compressor engages but the belt slips, squeals or shreds → start at the mechanical side.

2. Interface One — The Electrical Side: the Coil

Three figures define the electrical interface: coil voltage, coil power, and — on some units — the speed at which the clutch is rated. Across this range the coil is stated at 24 V with power from 60 W and up, and the rated speed is 4,000 rpm.

One listing pushes further and publishes a 5,000 rpm instantaneous maximum alongside a static friction torque of ≥ 320 N.m. That is the one unit in the range stated with a torque figure rather than a nominal torque value.

3. Interface Two — The Mechanical Side: Pulley and Groove

The mechanical interface is where most wrong-part purchases happen, because the groove designation in this range is not written in PK notation. The supplier writes 2A2B, 2A-2B or 2A+2B — three spellings of the same groove arrangement depending on which field you read.

4. Five Clutches, One Comparison Grid

Every value the listings record, side by side. Read the grid across the row you care about rather than top to bottom.

5. Matching Either Interface to Your Compressor

Two routes, depending on what you already know.

If you know the compressor model

Work from the *fits compressor* row in the grid. The range covers the Bitzer 4-series (4NFCY, 4PFCY, 4U, 4T, 4P), the BOCK FKX-40 and FKX40, the 390-650 class, HISPACOLD 4050294 and Thermo King X426 / X430.

If you only have the old clutch

Measure the pulley across its largest diameter and record the groove arrangement as it is stamped or moulded on the pulley face. The three outer forms in this range — 260/210, 260 × 216 and 226/197 — are not interchangeable, and the groove form decides the belt.

6. Measure Before You Order

1. Largest pulley diameter — 260 or 226 separates the two families immediately.

2. Groove arrangement as marked — expect an A/B designation rather than a PK number on these units.

3. Coil voltage — 24 V is standard across the range; confirm 12 V / 24 V if your vehicle is a 12 V system.

4. Compressor model — this alone usually settles it.

5. Send us the three figures or a photograph of the pulley face, and we will confirm the reference before dispatch.

260/210 2A2b clutch, 24 V, 60 W — for FKX40 and the Bitzer 4U / 4T / 4P / 4NFCY.

260 × 216 mm clutch — the unit carrying the 5,000 rpm and ≥ 320 N.m figures.

226/197 2A2B clutch for Thermo King X426 and X430 refrigeration units.

Clutch for the HISPACOLD 4050294 fitment.

260/-210 2A-2B clutch for BOCK FKX-40 and the Bitzer 4U / 4T / 4P / 4NFCY.

Q1. Do these clutches use PK groove notation?

No. Every listing in this range writes the groove as 2A2B, 2A-2B or 2A+2B. PK notation does not appear anywhere in the five listings, so do not convert one to the other when you are comparing against a catalogue.

Q2. Is the coil 12 V or 24 V?

24 V on four of the five units. The 226/197 unit for Thermo King X426 / X430 records both 24 V and 12 V / 24 V in different fields of the same listing.

Q3. What is the difference between 240 N.m and ≥ 320 N.m?

The 240 N.m figure is the nominal torque recorded on four units. The ≥ 320 N.m figure on the 260 × 216 unit is stated as a static friction torque — a different measurement — and that unit also carries a 5,000 rpm instantaneous speed rating.

Q4. Which clutch fits a Bitzer 4NFCY?

Three of the five cover the Bitzer 4-series: the 260/210 2A2b and the 260/-210 2A-2B both list 4U / 4T / 4P / 4NFCY, and the 260 × 216 lists 4PFCY / 4NFCY alongside FKX40 and the 390-650 class.

Q5. What warranty applies?

1 year across all five units.

7. Certificates, Test Regime and Inspection

Evidence you can actually use: test data for the model you are buying is available on request, and the plant is open to your own audit or a TÜV, SGS or BV inspection before dispatch.

8. Certification and Test Report Register

Everything the plant holds, by number — from the automotive quality system registration through the E-mark approvals to the CE, RoHS and Low Voltage/EMC declarations.

1. IATF 16949:2016 quality management system — scope: design and manufacture of air blowers for air conditioners [USI CKMMPC] — Certificate 126765/A/0001/SM/En (CN registration 126765/A/0001/SM/ZH); IATF No. 0475895. Issued by URS — United Registrar of Systems, issued through URS Certification (Hangzhou) Co., Ltd.; verifiable at www.cnca.gov.cn. Issued 06 June 2023, valid to 05 June 2026.

2. ECE type approval — components for vehicles, qualified for production in series (E57, Republic of San Marino) — Approval E57*COP*1682; inspection report ATS-SM-IR-COP-13381. Issued by Authority for Homologation, Republic of San Marino (technical service RSMAO-01). Inspected 15/05/2024, valid to 14/05/2026.

3. ECE Regulation No. 10 approval — electrical/electronic sub-assembly, 24 V DC, vehicle categories M, N and O; type WLNF343-4 (variant WZHF2101-3) — Approval E57*10R06/02*0809, extension 00; inspection report ATS-SM-IR-10-13380. Issued by Authority for Homologation, Republic of San Marino; AUTOMOTIVE TECHNICAL SERVICE S.r.l.; tested by Guangzhou LCS Compliance Testing Laboratory Ltd. (ISO 17025). Report 05/06/2024, approval issued 11/07/2024.

4. CE — Electromagnetic Compatibility Directive 2014/30/EU, tested to EN IEC 61000-6-3:2021 and EN IEC 61000-6-1:2019 (brushless fan) — Certificate TBC-C-202308-0315-1; test report TBR-C-202308-0315-1. Issued by Shenzhen Toby Technology Co., Ltd.. 17 October 2023.

5. RoHS — Directive 2011/65/EU as amended by (EU) 2015/863, tested to the IEC 62321 series (brushless fan) — Certificate TBC-C-202308-0315-2; test report TBR-C-202308-0315-2. Issued by Shenzhen Toby Laboratories Inc.. 23 October 2023.

6. Low Voltage Directive 2014/35/EU (Annex III) and EMC Directive 2014/30/EU (Annex II) — EN IEC 60335-1:2023, EN 62233:2008, EN IEC 55014-1:2021, EN IEC 55014-2:2021, EN IEC 61000-6-1:2019, EN IEC 61000-6-3:2021 (brushless fan) — Certificate M.2024.206.C110335; report TCF-OY20241115-EMCLVD-A. Issued by UDEM International Certification Auditing Training Centre Industry and Trade Inc. Co. (Ankara, Türkiye); verifiable at www.udem.com.tr. Registered 26.11.2024, valid to 25.11.2029.

Traceability. Every row can be checked independently: the IATF registration through the issuing registrar, the E57 approvals through the San Marino Authority for Homologation, and the CE / RoHS / Low Voltage-EMC declarations through the laboratories named. The brushless fan approvals name their covered models on the certificate, which we send on request.

IATF 16949:2016 registration certificate 126765/A/0001/SM/En — valid to 05 June 2026.

ECE type approval E57*COP*1682, Republic of San Marino — valid to 14/05/2026.

CE / EMC certificate TBC-C-202308-0315-1 — test report TBR-C-202308-0315-1.

RoHS declaration TBC-C-202308-0315-2 — test report TBR-C-202308-0315-2.

Low Voltage / EMC certificate M.2024.206.C110335 — valid to 25.11.2029.

9. Ordering Quantities and Production Time

The four questions that come up on almost every first order, answered the way we answer them on the quotation.

Lead time is confirmed on the quotation, not estimated. The exact production period depends on the quantity you order and the current schedule, so it is written into the quotation rather than left as a range.

As published on the official listing for each reference above. Production time is the period stated to produce the goods before dispatch; the exact figure for your quantity is confirmed on the quotation.

10. The Factory Behind This Part

Hunan Weili Auto Parts Appliance Co., Ltd. was founded in 2007 and manufactures only bus and truck air-conditioning components — which is why the range is deep rather than broad.

Why it matters commercially: the parts are made in our own plant rather than bought in and resold, so a technical question about a compressor, fan or water pump reaches the people who build it.

11. Plant and Production Line in Photographs

Confidence stems from quality, and quality changes the world — which is why the line that makes this part is open to your inspection.

The plant in the Xiangtan Economic and Technological Development Zone, Hunan Province, China.

Assembly line — blower and fan assemblies built and inspected at the bench.

In-house motor winding — stators wound on an automatic winding machine.

Production line — components staged at the stations along the line.

Finished-goods warehouse — export cartons staged for dispatch.

Brand wall and the on-site certificate and reference display at the plant.

A visit is the fastest way to settle a sourcing decision. The address and line access are open to buyers who want to verify capacity, equipment and quality control before committing to a programme. Pre-shipment inspection by SGS, BV or TÜV to a standard you nominate is part of the process, not an exception.

The parts on this page are wound, moulded, stamped, assembled and tested inside the plant shown above, so a technical question reaches the people who build it rather than passing through a trading desk.

12. Private Label and Custom Development

Development cycle. Requirement collection begins as soon as any one input arrives — an OE number, a sample, a drawing or a parameter table. Solution confirmation follows, with dimensional mapping and a quotation. A standard sample-based project produces a sample in approximately 30 days; mass stocking is 40 – 60 days after the sample is approved, subject to process and quantity.

Cost position. Small changes such as silk-screen, labels or harness length are usually free or carry a small revision fee. New tooling carries a mould cost, refundable or amortised once the agreed volume is reached. Customised order quantities depend on the tooling and process involved, and the company deliberately accepts small-batch trial orders that larger plants decline.

Traceability. Customised parts are supported by dimensional mapping and trial fitting at development, a pre-production sample before the batch, and first-article inspection plus in-process sampling with records for key dimensions, dynamic balance and electrical parameters.

13. Who Buys This and What It Replaces

The customers behind this part are wholesalers and repair chains rather than one-off buyers — which shapes how the numbers work for them.

• Buyer profile — aftermarket replacement wholesalers, air-conditioning conversion workshops and fleet customers across the Middle East, South America, South East Asia and Eastern Europe.
• Market concentration — Mexico, the UAE and the Philippines are the three largest export markets.
• Cross-referenced brands — SPAL, Valeo, Thermo King, Webasto, Scania, Yutong, DAF, Mercedes, Volvo and Hwasung Thermo.
• Vehicle coverage — passenger cars, buses and coaches, heavy trucks and semi-trailers, and large vehicles including construction machinery, forklifts and mining trucks.
• Repeat-buyer terms — long-term partners receive dedicated account service, priority production scheduling and a tiered rebate policy.
• Verification — factory visits and audits are welcome, and the platform record (rating, on-time delivery rate) is public.

Universal-fit first, OE-specific second is the usual shelf strategy: stock a universal 12 V / 24 V range to cover walk-in demand, then lock in the OE-specific references that your repeat customers ask for by number.

14. Purchase Questions We Are Asked Most

Q1. How small an order can I place?

Standard catalogue items start from as few as 1 – 2 pieces (some blowers from 1 piece, condenser fans from 2 pieces); batch items are typically 6 – 50 pieces; customised items depend on the tooling and process involved.

Q2. Can I test the quality before committing to volume?

Yes — a small-batch trial order is the normal route. Confirm quality and cooperation on a low quantity first, then scale. The agreed quantity, production time and shipping method are confirmed together with the quotation.

Q3. What warranty applies?

1 year across the range.

Q4. How do you package for export?

Standard export packaging — inner box, outer carton and shock cushioning — is included in the quotation. Colour boxes, wooden cases, palletisation and brand printing can be added. Packaging is designed to sea-freight standards, with drop and compression sampling before dispatch.

Q5. Can third-party inspection be arranged?

Yes. SGS, BV or TÜV can inspect before shipment to a standard you nominate, such as AQL sampling, and the goods ship once the inspection is passed.

Q6. Can I mix several models in one container?

Yes. Multi-model mixed loading into a single container is supported, with cartons marked by destination, which uses the space better and spreads the freight cost over more units.

Send Us the Pulley Dimensions

Hunan Weili Auto Parts Appliance Co., Ltd. — founded in 2007, ISO 9001 & IATF 16949 certified manufacturer of bus & truck AC parts, electric fans, blowers, lighting and alternator components.

Give us the largest pulley diameter, the groove designation and your compressor model — or a photograph of the pulley face — and we will confirm the clutch within 24 hours.

WhatsApp / WeChat: +86-18670382782 | Landline: +86-0731-82034997 / 82034998

E-Mail: [email protected] | Websites: www.cooliparts.com | www.weilipart.com | www.weiliautomotive.com

Send us your OEM part number, vehicle model or drawing — we will reply within 24 hours with a quotation and technical data sheet.