Wednesday, October 12, 2022

Hard To Find Refrigerant Leak

In a move that leaves most people scratching their heads, I enjoy keeping my 1967 Airstream Overlander’s original air conditioner running.  Usually, the problem is somewhat obvious and with occasional help from a professional is quickly resolved.  However finding a refrigerant leak that popped up after returning home from our last outing proved to be quite the challenge.

The outing itself was, in itself, a bit challenging – we had to pack a dorm room’s worth of clothing & furniture into the Airstream & truck to return number 2 son to the University of Alabama and a hide-a-bed sofa plus incidentals into the truck to leave at the condo in Tuscaloosa where number 1 son had been living.  We stayed at a new-to-us campground near UA.

After getting number 2 son situated, we then proceeded to the condo to pack number 1 son’s clothes & incidentals for a move to a fully furnished apartment near the University of Florida.  Once in Gainesville we stayed at a new, very nice campground.  There was even another Airstream dad there doing a similar drill for his daughter.

After getting number 1 son situated at UF Kim & I drove further south to Fort Wilderness to enjoy a week at Disneyworld.  We always enjoy our visits there and this time was no exception.

We used the Airstream’s air conditioner every day at each campground, and it performed flawlessly.  Sadly, while cleaning the interior after returning home the next day I noticed the temperature had not dropped much while the AC was on.  Only one of two banks of evaporator coils was cold, and it had frost forming on part of it – a sign of low refrigerant.

Several years ago, the Overlander got an Airstreamport to cover its parking pad.  To facilitate the use of the various air conditioning tools required, 2X4 “joists” were strung between two of the metal studs.  Sized 2X12s were then laid across the 2X4s on either side of the AC as decking.

After removing the shroud and case cover, one of the two condenser coil assemblies was found to have an oily residue.  This is usually indicative of a leak path.  But since this is in the location of a refrigerant leak repair done five or so years ago by someone else there was the possibility that it was old, uncleaned-off oil.  It seemed prudent to continue looking for another leak path.  Since the AC had gone from cooling just fine one day to barely cooling at all the next day, I figured the leak should be big enough to find in a reasonable amount of time.

Normally I get my friend Kenny to help me with his specialized HVAC tools.  But since he was up to his armpits in other projects in his free time, he was happy to loan me his refrigerant leak detector.

After adding a little refrigerant to the system, sure enough the leak detector went wild every time its wand probed the oily area.  To isolate the exact leak location the area was cleaned with coil cleaner in hopes the leak would bubble through the soapy solution.  When that did not work Formula 409, my usual go-to leak detector was used.  Realizing no joy again, a bottle of official leak detector was purchased & daubed everywhere.

It too, oddly enough, failed to bubble anywhere I could find.  The condenser coil assembly was then removed from the air conditioner & thoroughly cleaned, inspected and leak-checked again with shop air with no new result.  So, it was then pressurized to 120 psi in a bathtub full of water.  To my phenomenal surprise there were no detectable bubbles.

Since there was no heated rush to get the unit repaired, I took a step back and started texting with three buddies who have more experience than me in these types of repairs.  Although everyone was comfortable with my reasoning and sequence of steps, we all agreed the major leak path had not been located yet.  We also agreed that my technique using the leak detector might need improvement.  The Internet was here to help & had a plethora of proper leak detector usage suggestions which I took to heart.  Feeling newly empowered with better technique it was now time for round two in the leak detection ring.

As Kenny was still busy with his projects, he loaned me his oxyacetylene rig so the condenser coil assembly could be silver-soldered the back in.  Of note, SIL-FOS is both the current Industry Standard in brazing filler and Kenny’s preference.

Although the acetylene bottle was empty, the local welding gas supplier had no problem with me swapping it and a few bucks for a refilled one.  

Since it has been quite a while since I have used an oxyacetylene rig, Mr. Google provided me with a picture of a proper flame’s appearance to refresh my memory.

Between my long-time experience soldering copper water supply lines and practicing with Kenny’s rig on copper fittings out of my spare parts box I felt up to the challenge of attempting the re-installation of the condenser coil assembly.  To my relief the operation appeared to go well.

Although there did not appear to be any leakage at the Shrader valves, both inserts were replaced with new ones for good measure before continuing.

The unit was then pressurized with refrigerant in the calm of an early Saturday morning and allowed to stabilize while I climbed down for another cup of coffee.  The leak detector was then trotted up the ladder to continue the quest.  This time it never lifted an eyebrow at either condenser coil.  But it repeatedly sounded off at the TEE from the compressor that feeds both coils.  After slathering the TEE with leak detector and patiently waiting, a small, genuine leak was found on the bottom of the left side of the TEE with an inspection mirror.

For complete disclosure, in the picture above the copper line to the left of the TEE was replaced in a repair about five years ago.  So, this was technically a cold solder joint that took a while to have a problem.  Notice the pulled-back metal panel on the right side of the image - the technician who did the original repair did not have that luxury and could only work from above.  Honestly, I am surprised there ended up being a problem.

After thoroughly Scotch-Briting the TEE and then getting Kenny’s rig involved again I swelled with pride over finding the exact problem and doing a good aesthetic job of repairing it.  So, the unit was then pressurized, and I will be dog-gonned if it did not leak faster!  After calming down I decided something else simple had gone wrong.  Backtracking, the gauges were pulled off and the low-side Shrader valve was found to be leaking.  Although we do not want that, it should not have been a problem with the gauges connected.  Regardless, both inserts were tightened before re-connecting the gauges.

Success!  This time there appeared to be no leak and the pressure appeared to go up as the morning warmed up as would be expected.  My buddies all agreed that I must have not had the gauges screwed on well as the Shrader valves would not have figured into that scenario.

The vacuum pump then pulled the system down to 24 inches in short order and held it while I ran an errand.  After purging once, the system pulled down to 26 inches and held that while the yard was cut.  My trio of experienced friends confirmed my thought of the unit was good to recharge.

As I bought my Airstream from the original owner, part of the package involved getting the Factory-included paperwork from 1967.  One of the documents was from the Armstrong Air Conditioner company who manufactured my Bay Breeze model unit. It included the weight of the system’s charge of R-22.  After hoisting the scale up, the proper charge of liquid refrigerant was weighed in on the HIGH side with the unit off.

The rubber O-rings inside the 55-year-old AC’s Shrader valve caps had eroded so new caps were purchased after my favorite parts store cackled when asked for just the O-rings.

The air conditioner fired right up and began dumping out cold air through both sets of evaporator coils.  In short order it also began dripping condensate.  My trio of experts agreed the repair was a success.

As this is being written a couple of weeks after the repair, I just now confirmed my Bay Breeze is still dumping cold air out on both sides.  My HVAC buddies and I agreed that the leak detector might have “lit” on the condenser coil at the start of this post because the sprayed oil stilled smelled like refrigerant from the original leak.  No clue.  Fortunately, my bottle of R-22 has enough left for two or three more repairs.  If they each happen five years apart, I think I’m good.  As an aside, when I was at the HVAC store buying piece-parts for the repair, I noticed 10-lb bottles of R-22 for sale.  The fella behind the counter told me those were going for about $1000.

Ah! The joys of Vintage Airstream ownership!






Saturday, October 30, 2021

Re-discovering Music As I Get Older


Like many people I enjoyed playing in the school band while growing up.  Since I had already learned how to read music while studying piano before then, trumpet was easier for me as opposed to others not so fortunate.  But I really wanted to play trombone instead of trumpet.  Life with parents in the '70s was what it was and I got over it.

Jump ahead to eight years ago.  I decided to teach myself trombone.  It went so well that I progressed to euphonium and tuba.  Although the trumpet was re-integrated into my world about four years ago it is obvious to me that I should have been a low brass player because I am getting good at it.  

My childhood piano was wheeled into the practice room at one point and it was instrumental in helping me slot notes while learning the tuba.

All this went really slow because in the last few years because I had a beer or two before starting practice.  Week day drinking has now stopped.  The fun has begun.

As i related to my siblings, "I was never big shakes on the piano.  But after getting kind of good at my myriad of brass instruments I have returned to practicing the piano.  Trying to learn Bach 2-part Inventions today for my own reasons.  Practicing longer now on piano than I ever did for Mrs. Wooten and brass than I ever did in high school.  I finally want to."

Here's a shot of "Tom's Room".  Have a happy Halloween!

Monday, December 28, 2020

Transporting 100 Pounds of Propane in PU Truck

 For lotsa reasons I have always wanted to have a 100 pound bottle of propane around in case of emergency.  I finally pulled the trigger the other day after getting 20 lb & 30 lb bottles refilled.

The biggest challenge from a DIY viewpoint is transporting the charged bottle in a vertical position.  The Internet was strangely silent on good ways to do this.  So here is what I think is a good way.

The base needs to be constrained just like the top.  After looking at my truck, I decided the tank needed to sit forward of the front of the front of the bed just to get a good angle on the tie-down straps.  Don't beat me up on the big whomp on the front of the bed - I had help...


Thursday, March 19, 2020

New RV Furnace Installation

Remarkably, the furnace in my 1967 Airstream travel trailer checked out fine during the 2004 refurbishment, and has been used for the last 16 years without any significant repairs. But after the pilot light started having trouble staying lit near the end of last season, following a checkout I decided it was better to replace the old Suburban furnace with Suburban’s newest, matching model rather than repair the old one.

Although the old & new furnaces are functionally identical, the new unit is shorter and thinner. Also, the old style forced heated air out of a rectangular hole on the bottom into a plenum instead of out of round holes on the sides. Fortunately, the new furnace is backwards-compatible in that it had a blocked-off rectangular hole on the bottom. The Internet sold me cover plates for the round holes.

Another design change over the last half century is that the old furnace slid into its outer housing which is permanently mounted atop the plenum. The new furnace has no plenum.

The housing needed to be removed in order to properly align the new furnace with the existing air intake & exhaust ports. Unfortunately, the enclosure had been placed in the Airstream before the cabinets were installed. Short of removing the cabinet something would need to be cut to remove it. I chose to cut the housing with a cutting wheel on an angle grinder.

Worked great! Unfortunately, I forgot the gas line was near one side. Oops.

After cutting the housing remains off of the plenum, the next step in aligning the new furnace was to make a cardboard pattern of the exterior ports with respect to the plenum.

The plenum was then placed back in the Airstream. The holes in the cardboard were found to be one inch lower than the holes on my American classic. After noting that, the block-off plate on the bottom of the new furnace was addressed.

A one-inch thick board the width of the plenum and depth of the back-of-the plate-on-the-furnace was then screwed to the top of the plenum. The hole on the top of the plenum was then modified to match the dimensions of the outlet hole on the bottom of the furnace.

Individual pieces of sheet metal were then cut & bent both to block off areas of the old hole which were no longer needed and to direct air from the furnace into the plenum.

After firmly mounting both the plenum & furnace in the Airstream, the new work was sealed with aluminum tape.

Although the ports on the old & new furnaces were the same diameter, the distance between them was not. Ovalizing the bottom port with a Dremel tool resolved the issue.

No one will ever see it, though, because the cover plate does its job quite well.

After the old furnace gave me trouble last season it was pulled out and thoroughly inspected. To my surprise, the space beneath the burner was completely filled with an old yellowjacket nest.

Although the nest was partially blocking the burner’s inlet air, it was not responsible for the pilot not staying lit. That problem is probably due to either a bad thermocouple or gas control valve neither of which are available now new. But to guard against future nests, screens were installed over the ports.

The old furnace’s pilot light had to be lit by hand as needed and was accessed by removing the front panel. The new furnace has auto-ignition. Hopefully it will be a long time before I need to remove its front panel.

As hoped, the new furnace ran like a champ after the gas & electrical connections were made. It’s much quieter than the old one even though I never considered the old one a problem. 

We’re now ready for cold weather again! 


Wednesday, July 17, 2019

Better Curves for the T&K Railway

My O-gauge ceiling railway was originally designed for 27-inch radius curves simply because that was all the curvature my childhood’s Lionel 2034 locomotive and cars required. In time, though, I found it difficult to expand my rolling stock collection because everything on my wish list required O-31 curves or better. Fortunately, O-31 curves just fit the existing shelving built for the railway which allowed me to do nothing more than swap 0-27 curves and track with the corresponding O-31 version.

All was relatively well until Bill, one of my wife’s co-workers, after learning of the railway decided to loan me some nice locomotives & cars he had in storage because he now did not have access to a model railway. Unfortunately, some of his collection would only run on O-42 or better curves. Since a really cool Shay locomotive was one of those items, the decision was made to modify the T&K’s shelving to accommodate 0-72 radius curves since that curvature appears to be the largest in regular production.

Due to the amount of shelving which could not be aesthetically attached to the walls, four pieces of ¼-inch All Thread per curve was incorporated into the design. As before, the new design was drawn up in AutoCAD.

Last time, each of the four curve sections were individually cut out and shaped to final dimension in assembly line fashion. Since the whole operation could have gone a lot better, this time I decided to make a pattern out of 1/8-inch hardboard and use a template guide on the router to mill the four, 5/8-inch MDF shelving curves from the pattern.

There has never been a point in my woodworking career, up until now, to draw 5-foot and larger radii. Fortunately, a yardstick compass will work once the yardstick is swapped out for a really long piece of hardboard.

After completing all the construction lines, the new track itself was laid on the proposed template for a quick sanity check. We’re good.

Unlike drawing large radii, I have routed large curves with a homemade jig. The jig was frustrating to use because each different radius required a new pivot point hole to be drilled in the jig. Getting past this stumbling block was a little more problematic because the longest, store-bought router compass I could find only did 24-inch curves. So two, long sections of 1/8-inch hardboard were glued together and milled to match the important dimensions of the store-bought version. Then the store-bought version’s hardware was remounted on the homemade version.

The result was a really easy to use, long router compass.

The tabletop drill press, mounted on a special stand & fitted with various Forstner bits, was used to provide radiusing on the inside corners.

After the master pattern was cut out and touched up with a drum sander attachment on the drill press it was used to rough out the four corner blanks.

The blanks were cut proud of the construction line with a jigsaw.

Then the ends were squared off with the radial arm saw.

With compass routing complete, the router was refitted with a template guide collar.

Then, with the template C-clamped onto each blank, the router was run around the perimeter to establish the final dimensions.

Next stop was the router table fitted with a round-over bit.

Soon afterward, the O-31 track & associated track wiring/lighting was removed for test fits. The new O-72 curves will be a big improvement over the ones originally designed for O-27.

Portions of the old O-27 shelving were cut out by jigsaw, small circular saw and hand saw. A 2X4 stand helped support the new curves for fit checks.

All empty biscuit slots and holes were then filled with wood putty. After fit checks, the new curve sections were returned to the shop for pocket holes.

Since I elected to leave the track wiring and LED lighting in place during the upgrade, it was taped off while the new curves were installed, caulked, primed, and painted.

My little ¼-inch right angle adapter has paid for itself countless times with tasks like drilling pilot holes in tight places.

I was very happy with how it all turned out:

Now to see what else Bill has!