Description

Mack GU, CHU, CXU, MRU, LEU 2007 Service Manual – A/C System Factory Specs

Air conditioning that won’t blow cold in a San Antonio summer? Or a blend door that clicks but never shifts? I’ve seen too many guys throw parts at a Mack HVAC system because they were using some aftermarket “universal” guide that left out the critical R-134a vs. R-12 differences. This Mack GU, CHU, CXU, MRU, LEU 2007 Service Manual is the real deal—188 pages of factory-written procedures from Mack Trucks, Inc., specifically for U.S. ’07 chassis. No generic A/C theory; this is the exact document that covers the Red Dot, Blend Air, and BEHR systems on your Granite, Pinnacle, or TerraPro. If you’ve ever had a customer’s compressor grenade because you used the wrong oil—buy this. If you’re a DIY guy pulling a cab in your home garage—buy this.

SAFETY INFORMATION – Why Page 2 Matters

Page 2 of this manual opens with advisory labels and personal safety rules. That’s not fluff. Working on R-134a systems without knowing the “Do’s and Don’ts” (page 6) can send refrigerant into your lungs or cause a blowout. The manual dedicates three full pages to safe tool usage and refrigerant handling. I’ve seen a technician lose a finger when a Schrader valve blew out because he used a cheap gauge set. This section tells you exactly what tools Mack requires—no guesswork.

Does It Cover the BEHR System?

Yes, and that’s a big deal. The BEHR system appears on CTP, CXP, CHU, CXU, and GU models. Many aftermarket manuals skip it or give you a generic diagram. This manual breaks down the BEHR evaporator, expansion valve, and blower motor with factory part numbers and wiring callouts. If you’re troubleshooting low airflow on a 2007 GU, you need the exact control panel layout from the “A/C SYSTEM FEATURES AND OPERATION — BEHR SYSTEM” chapter. Don’t trust a photocopy from a third-party site—get the OEM source.

3 System Variants Detailed

The manual splits the A/C system into three distinct sections: Red Dot [637], Blend Air [637], and BEHR [637]. Each section includes system descriptions for different cab configurations. For example, the MR and MRU cab-mounted A/C system (roof-mounted for LEU) has its own climate control panel drawings on page 16. The CH, CL, and CX systems are covered separately because the ductwork and compressor mounts differ. If you try to use a one-size-fit-all diagram, you’ll waste hours chasing the wrong wire.

R-134a vs. R-12: Component Differences

Page 6 has a table of “Do’s and Don’ts” for R-134a conversion. This isn’t found in generic manuals. It lists compressor oil compatibility, O-ring material, and pressure switch differences. Never mix R-12 components into an R-134a system without checking these specs. The manual also includes “Additional Service Precautions for R-134a Refrigerant” on page 7—stuff like accumulator orientation and torque values for service ports. If you’re retrofitting an older Mack chassis, this section alone saves you from a comeback.

Get the Right Torque Specs – Fast

Torque values for compressor mounting bolts, hose fittings, and accumulator brackets are scattered through the service procedures. But the manual’s “Explanation of Numerical Code” (page 9) tells you how to decode the three-digit numbers that reference torque specs in the Mack parts system. If you see a code like [637], that’s a system identifier—you cross-reference it with the torque tables later in the book. This is the kind of detail that separates a factory manual from a pirated PDF. Related: check out the Mack GU CHU CXU TD Electrical System Troubleshooting Manual if you’re tracing a short in the cab harness. For driveline work, the Mack CHU CXU GU TD 2010 Diagnostics Manual covers engine controls. And the Mack TerraPro MRU Series 2010 Operator’s Handbook is handy for cab layout references. If you’re also dealing with the Manual Transmission on your Mack, that’s a separate document—but this A/C manual stays on my bench whenever the compressor won’t engage.

FAQ

Does this manual include the MRU roof-mounted A/C system?

Yes, page 16 covers the LE and LEU roof-mounted system.

What’s the difference between the Red Dot and Blend Air system chapters?

The Red Dot system uses a receiver-drier and thermal expansion valve; it’s found on CH, CL, CX, and older DM models (pages 12–18). The Blend Air system uses a different control panel layout and duct door actuator, covered on pages 19–22. Both use R-134a, but the service procedures for evacuating and charging differ because the low-side service port location changes. The manual spells out each step with OEM part numbers and wire colors—no interpretation needed. If you misidentify the system, you risk using the wrong orifice tube or overcharging. I’ve seen it happen.

This manual is the one piece of paper that keeps your Mack A/C running right. Don’t rely on a faded printout from the previous shop. Access the Factory Manual and get the genuine 2007 service data—complete, searchable, and printed on demand from the official master file.