Harrison R4 AC Compressor Repair Tutorial
Jan 1, 2010
This DIY tutorial illustrates removal and installation of the clutch, pulley and magnetic coil of a Harrison R4 AC compressor in a 1992 K1500 Chevy truck. First off, I am not a professional mechanic so some steps are a bit unorthodox since I had to improvise along the way. It was hard finding information to do this repair myself and I didn't want to pay a shop to do it. I felt the repair was easy enough for a DIY project. This is a repair on a budget and one many should be able to tackle if so inclined. Although this tutorial is specific to the R4 compressor I hope you'll find it helpful in some way with your own project. Hopefully I can at least empower you to do self-repairs on your vehicle.
The problem I had with my AC compressor was a broken plug on the magnetic coil. The magnetic coil is simply an electro magnet. When it's powered it pulls the compressor clutch against the rotating pulley and in turn runs the compressor. For comparison the first image above shows the repaired compressor while the second image shows the missing magnetic coil plug.
Finding a replacement magnetic coil was a pain. I ended up going to Ebay and getting a refurbished one for $25. A lot of times it comes as part of a kit which includes the pulley and clutch together but you end up paying more. Since this is a budget repair I opted to simply get the coil and reuse my existing pulley and clutch.
There are several tools needed for this job and I was fortunate enough to have Autozone and Checkers stores in my area that rent them out free of charge as long as you return the tools within the allotted time. It's best to have all replacement parts at hand before going out and renting the tools. The tool kits they have come with several tools but not all of it you'll need. Use only what's appropriate for your compressor. Don't be surprised if the tools you rent are broken or worn out which was the case with me. A lot of people rent these kits and sooner or later something will break. When I had no alternatives I modified the tools that were worn out to make them usable for my purpose. I'll discuss that later on. Hopefully you won't have to go through the trouble I did.
- A/C Clutch Remover & Installer Kit by Powerbuilt (Kit #65)
- Puller Kit (OEM27001)
- A/C Clutch Puller Jaws (OEM27008)
- Socket Wrench
- Adjustable Wrench
- Snap Ring Pliers
- Feeler Gauge
This repair doesn't involve the removal of the compressor from the engine block. We begin by removing the serpentine belt around the compressor pulley. Then remove the compressor shaft nut using a socket wrench (1). The clutch has threads so take care not to damage them with the socket wrench. Use the spanner wrench (2) to keep the clutch from moving if necessary. Notice the clutch has three holes for the spanner wrench to grab onto.
With the nut removed you can now see the compressor shaft which is slotted and a rectangular key inserted. The key keeps the shaft from slipping as the clutch spins. I also made it a point to have the slot at 12 o' clock. This will make it easier to reinstall the key later on.
The clutch puller tool I used is part of Kit #65. It comes in three pieces: a bolt, outer nut and a small screw that goes at the tip of the bolt. It is used to both remove and install the clutch simply by flipping the outer nut. The image below shows the tool configured for clutch removal.
I thought it important to mention that I rented several Kit #65 from Autozone and Checkers and found the tools were in bad shape. The threads were worn out. Since the tools were unusable I improvised by cutting off the worn-out threads to make the tools usable. Of course Autozone and Checkers doesn't need to know about that.
We're ready to remove the clutch. Screw the outer nut of the clutch puller into the clutch. It should look like the image below.
You'll need both hands in this step. Put a crescent wrench (3) on the outer nut and a socket wrench on the bolt as shown below. Basically, you turn the socket wrench while the crescent wrench holds still. As you turn the bolt clockwise the outer nut and clutch should remain stationary. The tip of the bolt will press against the compressor shaft and draw the clutch out with each turn.
With the clutch removed you can now see the rest of the pulley as shown below. The pulley/bearing assembly is press fitted onto the compressor and a snap ring holds it secure. Also visible is the rectangular key in the shaft slot. Carefully remove the key and put it somewhere safe. It's best to have something directly underneath the compressor while you're working to catch anything you may drop as you'll undoubtedly drop the key a few times like I did. It is not fun trying to look for this small key in the engine bay. If you do lose it Home Depot has a few different sizes.
If you see a lot of oil in here you probably have a leak in the shaft. That is refrigerant oil. I won't cover that repair.
Using a snap ring pliers or a needle nose pliers(4) remove the snap ring as show in the picture below. I highly recommend using a snap ring pliers. Needle nose pliers suck for this job!