Hyundai HD65, HD72, County Training Manual – Factory A/C System Guide

You have a Hyundai County bus or an HD65/72 truck with an A/C system that’s blowing warm air. You’ve checked the refrigerant charge, maybe swapped a compressor, but the problem comes back. That’s because you’re guessing. Without the factory training manual, you’re working off memory or aftermarket fluff that skips the electrical diagnostics. This Hyundai HD65, HD72, County Training Manual is a 61-page document written for Hyundai service techs. It doesn’t assume you know the pressure-temperature relationship for R134a. It teaches it. Then it gives you the exact wiring diagrams and service points so you can fix it once.

Chapter I: Principle of Refrigeration – Three Laws You Must Know

Page 3 starts with the behavior of heat. The manual doesn’t waste space on theory you don’t need. It gives you three physical laws: heat flows from higher to lower temperature, the greater the temperature difference the faster the transfer, and transfer continues until both temperatures equal. That’s the foundation for diagnosing why your evaporator isn’t getting cold. The manual includes a real-world example using glasses of water and ice cubes. You can do that on your kitchen counter. Then it applies those laws to the engine cooling system and the A/C circuit. If you skip this chapter, you’ll be chasing symptoms instead of causes.

Chapter IV: Electrical System – 61 Pages of Concrete Wiring Data

Electrical diagnostics are where most DIYers and even some techs screw up. This manual devotes pages 24 through 47 to the electrical system. That’s nearly half the book. It covers the compressor clutch circuit, condenser fan relay, blower motor controls, and the control unit. You get the pinouts, wire colors, and voltage checks. For a 2015 HD72, you can cross-reference the 2015 electrical troubleshooting manual in Hyundai HD65 HD72 HD78 2015 Electrical Troubleshooting Manual for additional circuit-specific tests. The training manual focuses on A/C electrical, but it pairs with that related manual if you need engine or chassis electrical. The Automotive Industry Overview might tell you general trends, but this manual tells you exactly which wire carries 12V at the HD65 compressor clutch.

Chapter V: Service Points – Torque Specs and Refrigerant Charge

Page 48 lists the service points. This is where you find the factory torque values for the compressor mounting bolts, the O-ring connections, and the expansion valve. The manual also gives the refrigerant capacity in pounds (Imperial units) and the recommended oil type. Aftermarket manuals often say “tighten securely” – that’s how you snap a bolt. Here you get the exact ft-lb spec. If you’re swapping a receiver-drier, you need to know the correct torque for the line fittings to avoid leaks. This chapter has it. And it includes the evacuation and charging procedure with the proper sequence: vacuum for 30 minutes, check for leaks, then charge by weight. No shortcuts.

How Does This Training Manual Differ from a Service Manual?

A service manual tells you what to do. A training manual tells you why. This one starts with the physics of refrigeration so you understand the cycle. Then it walks through each component: compressor, condenser, evaporator, expansion valve, hoses. The troubleshooting chapter (Chapter VI, page 58) uses a symptom-based approach: low cooling, intermittent operation, noisy compressor. It gives you a decision tree, not just a list of possible causes. For the County bus, the A/C system is integrated with the body electrical – you can use Hyundai County Body Electrical System Manual to trace the power distribution. But for the A/C control head and compressor circuit, this training manual is your primary source.

3 Reasons to Choose OEM Documentation Over Aftermarket

First, the wiring diagrams are drawn by Hyundai, not a third-party copy shop. Aftermarket manuals often mislabel connectors or use generic symbols. Second, the refrigerant specifications are correct for the HD65 and HD72. A generic A/C manual might tell you to use R134a, but this one gives the exact charge weight and the superheat/subcool targets. Third, the safety warnings are explicit. The manual says when to wear gloves, when to use a recovery machine, and how to avoid refrigerant burns. That’s not fluff – that’s liability protection. Hyundai County Control System Troubleshooting Manual – Section: Charging System dives deeper into the charging system, but this manual covers the A/C side.

What Torque Values Are Listed in the Service Points?

Page 48 includes torque values for the compressor bracket bolts (typically 30-40 ft-lb on these Hyundai units), the expansion valve mounting nuts, and the O-ring flange connections. If you’re working on a 2015 HD72, the manual gives the specific foot-pounds, not Newton-meters. You need a torque wrench that reads in ft-lb. The manual also lists the refrigerant capacity: 1.8 lb for the HD65, 2.0 lb for the HD72, and 2.2 lb for the County bus. Verify with your vehicle’s label, but these are the factory numbers from the training manual. Automotive Industry Overview won’t help you here – only the OEM data will.

FAQ

Does this manual cover the HD65 truck with a non-A/C cab?

No. It covers only the A/C system. If the truck was ordered without A/C, this manual is not applicable.

Can I use this manual to retrofit an aftermarket A/C system into a County bus that originally had no A/C?

Not recommended. This training manual assumes the factory A/C system is installed. Retrofitting requires different brackets, compressor sizing, and ducting. You would need the factory body electrical manual and the HVAC installation guide. The training manual is for diagnosis and repair of the existing system, not for conversion. However, if you are installing a factory Hyundai A/C kit, the wiring diagrams and component specs in this manual will help you verify correct connections. Check the compressor mounting torque on page 48 and the electrical pinouts on page 24. The 61 pages cover the refrigeration cycle thoroughly, but they do not include instructions for cutting holes or mounting non-OEM parts. Stick to the factory parts list.

You’ve spent enough time chasing A/C gremlins with half-faded photocopies. This is a clean, original Hyundai 1st edition training manual. 61 pages, all the electrical data, the torque specs, the refrigerant charge. Download the Factory Manual and get the AC working before the next San Antonio heat wave hits.