A/C Compressor Clutch Inspection And Replacement Tips (B11080C)

A/C COMPRESSOR CLUTCH INSPECTION AND REPLACEMENT TIPS

TECHNICAL SERVICE BULLETIN

SERVICE INFORMATION

In the August '11 ServiceNews article "Engine Noise, A/C Not Working Right? Check Compressor Clutch First," we talked about troubleshooting an A/C compressor clutch with too much clutch clearance (air gap) or worn parts. Here's some good stuff to know if you need to further inspect that clutch and replace it. We've also included some valuable tips on getting that clearance right.

• To further inspect the compressor clutch, remove the armature plate and look for grooves worn into the friction surface. Check the rotor pulley for heat discoloration and the friction surface for spalled or smeared metal. Give the pulley a good spin, and check for a rough or noisy bearing.
• Most compressor clutch problems can be repaired. It's rare that you ever need to replace the whole compressor.
• To fix these problems, replace the compressor clutch (armature plate and rotor pulley). If needed, replace the field coil. If you do, make sure you also replace the clutch, or you could find yourself doing a lot of extra work and winding up with a comeback.
• To replace the compressor clutch and field coil, use the A/C Compressor Kit (T/N 07AAF-000A150). It's a required special tool that we sent to all dealers back in August '09. For a demo on how to use it, checkout the Tech2Tech segment "Safely Remove That Rotor Pulley with the A/C Compressor Kit."
• The rotor pulley and field coil are held in place with large snap rings. Make sure you remove them, or you'll damage the compressor housing. Use the new snap rings that come with the parts, and install them with the beveled side facing up (away from the compressor).
• Never  try to hammer or pry the rotor pulley off the compressor! You could crack or break its front housing, and that means compressor replacement-at your dealer's expense!
• To allow for new parts, always  check the clutch clearance with a feeler gauge, and change the armature plate shims if needed. Don't  assume the old shims will work or let the clearance just fall where it may. There's no guarantee the clearance was right in the first place or that the new parts have the exact same dimensions as the old ones.
• Clutch clearance doesn't  need to be super-precise, but it does  need to be within the spec in ISIS. If you're a perfectionist, aim for the low to middle  range.
• The replacement clutch set includes a shim kit, which you can also order separately from Honda parts stock. You'll typically get one shim in each of these thicknesses:
  • 0.004 inch (0.1 mm) 
  • 0.008 inch (0.2 mm) 
  • 0.016 inch (0.4 mm) 
  • 0.020 inch (0.5 mm) 

  The shim thicknesses aren't  marked or color-coded, so make sure you've got a digital micrometer or a caliper handy to keep things straight.

• Changing shims changes the clutch clearance by nearly a 1:1 ratio. Adding shims increases  that clearance; subtracting them decreases  it. To set the clearance, you might need more than one shim.

We've talked about adjusting clutch clearance, so what happens if you don't  get it right? Here's the lowdown:

• Not enough clearance:  The armature plate could rub or drag on the rotor pulley when the compressor is cycled off. That causes a big buildup of heat, which can damage the clutch and the compressor shaft seal.
• Too much clearance:  The clutch might not engage at higher engine compartment temperatures.
• No clearance:  The clutch stays engaged when the compressor should be off. System pressures and temperatures will climb since the radiator and condenser fans aren't working. The pressure relief valve could open to bleed off high-pressure refrigerant, causing poor cooling. You could also wind up with compressor and system damage.