Diesel Suburban: Air Conditioning Version 2.0

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When I build the Suburban and got it on the road last summer, I managed to maintain the deluxe system that the vehicle came with -- though some modifications were required.

It has front and rear A/C units and they are both run by a single good-sized compressor under the hood.  On the Chevy 5.7, this compressor was mounted on the front-left side of the engine and used a serpentine belt.  Through experimentation, I realized that the existing lines could be used to mount the compressor on the right side of the engine.  I switched to the Sanden compressor I'm currently using because these are modular in design and I could swap the block on the back for one with different connections if I had to improvise.  More importantly, it allowed me to use a double v-belt pulley available, and I didn't want to improvise a serpentine system.

Vibrations from the diesel engine destroyed these tubes on the A/C compressor.

Hot, humid summers are the norm in Indiana, and I got the A/C functioning right away on this machine.  I replaced the expansion valve in the rear unit, the orifice tube for the front one, and the accumulator/dryer.  After that, I added the right amount of oil, and charged it up with R-134a.  I got 40 degree air, and life was good.  It worked for a few months through the summer, and I didn't have any issues until we were on our trip to Colorado last October.  That's when one of the cantilevered tubes connected to the compressor broke.  I covered the pipe ends with some balloons to keep moisture out of the system, and we continued on our way to Colorado.  Thankfully, temperatures dropped for the rest of that trip, and we haven't needed air conditioning again until recently.

This is part of the new A/C line assembly. It attaches to the compressor using the bolt hole in the center of the block between the LOW and HIGH valves.  Note how much aluminmum tubing is held cantilevered -- making this assembly quite fragile.

Recently, as things have been warming up, I decided it was time to fix the air conditioning.  I had been planning on this, and it was in my budget.  I ordered another hose assembly online for $90.  It's important to note how the IN and OUT lines both attach at a single point, and that the aluminum tubes extend a long distance from these points cantilevered.  I don't recall if they were supported on the Chevy 5.7, but I knew that these would break again if I didn't support them.

So, I temporarily installed the new lines on the compressor, and started working with some angle iron I had laying around.  I ran one from the left-rear mount on the compressor to the lower bolt where the hose adapter attaches to the intake manifold.  I ran another across the two mounting points on the compressor's right side.  I ran a piece of angle iron between these two, making a rounded cut in it to cradle the cylinder in the line.  I built a small outrigger for the right-side bracket to support the other cylinder.  I put notches in the appropriate locations for some hose clamps I had laying around.

It's not easy to see in this photo, but the tubes are now supported by angle iron brackets and hose clamps. Further protection from vibration is offered by the EPDM rubber strips between the hose clamps and the cylinders.

The lines and the angle iron brackets were installed, marked, uninstalled, reinstalled, etc. until I thought everything was right.  Then I painted the angle iron components black.  When the paint was (mostly) dry, I did my final installation.  I put the brackets in, tightened the bolts, then put the lines on.  I didn't want metal hose clamps scuffing or creating any pinch points on those aluminum cylinders, so I used some EPDM sheet to help spread the loads.  I tightened the clamps to make things snug, but didn't overtighten them.

Since then, we went to a John Birch Society event in Columbus, Ohio.  On the way back we checked the fuel economy and found that we were getting 26 mpg on the freeway.  The engine is running smooth, the A/C is operating great, blowing 40 degree air, and life is good, again!