Rebuild Armstrong A/C on '69 Ambassador

[jmpratt]

So I'm living in my Ambassador in the California high desert and I wanted to make sure my a/c could handle the summer heat (about 110 all summer). I still have the original Armstrong TAC-110-1 air conditioner. When I bought the trailer last year, it just needed a run capacitor for the compressor and a little R-22. But it was noisy and 42 years old so I figured I'd give it an overhaul. After lots and lots of research and search for parts on eBay and across the internet, I finally got everything I needed. I bought a new rotary compressor that had a bit more capacity (13k vice 11k BTUs) but pulled less current than the old compressor. I also bought a new fan motor. I also decided to make the unit a heat pump instead of just an a/c. So I bought a reversing valve and new bi-directional filter/drier. Since these old units have capillary tubes instead of TXVs (thermal expansion valves), the refrigerant can flow either direction. To make hot, the refrigerant flows from the compressor to the indoor coil first. To make cold, it flows from the compressor to the outdoor coil first. The reversing valve is what changes this direction of flow. Anyway, after about four weeks of getting parts and four days putting it all together, it works like a champ! It was keeping me warm last week on some cool nights, and now it's keeping me cool during the warm days. I'll have to see how well it can handle the high summer temps! Pics to follow.

-Jason

[jmpratt]

The first pic is the a/c with the original compressor and fan (sitting next to it). A pretty simple system.
The second pic shows the reversing valve, new compressor, and new copper.
The third pic shows it installed back on top of the trailer.
The fourth pic shows the modified cover. I had to extend the back to fit the new compressor.

[Silverwanabe]

Cool,

I've always heard this is the only RV AC worth saving and rebuilding.

[Lance M]

Nice work. Always nice to see old stuff better than new.

[68 TWind]

Could you post a parts list with specifics.

Thanks

[jdalrymple]

Clean work! It is always encouraging to see one will skills apply them.

Regards,

[ventport]

What did all the parts cost, and what would a comparable new unit cost just for a comparison?

[Aage]

Wow, what a great job of bringing an important part of the AS up to date, plus adding functionality! Thank you for showing us that.

This might be a good candidate for becoming a "sticky" and getting added to the Hall of Fame here. As Silverwanabe said, there have been many comments around the fact that this machine is worthy of repair, unlike the newer ones, but who would have thought that the heat pump part could be relatively simple to add?

I too, am interested in hearing more about the specific parts you added and what precisely the steps are to do it.

Thanks very much in advance.

[jmpratt]

Originally Posted by ventport

What did all the parts cost, and what would a comparable new unit cost just for a comparison?

The compressor was $200, the fan motor was $50, the reversing valve was $40 and the filter/drier was $30. Plus another $75 for copper and other small stuff. Total of about $400. A Coleman 15K BTU heat pump is $731 at PPL.

[ventport]

Originally Posted by jmpratt

The compressor was $200, the fan motor was $50, the reversing valve was $40 and the filter/drier was $30. Plus another $75 for copper and other small stuff. Total of about $400. A Coleman 15K BTU heat pump is $731 at PPL.

Wow that is quite a savings. Could you post a step by step on how to do this for us handy people that have never done something like this before? Part numbers and where to buy would also be very helpful. Don't some of the electrical controls need to be changed to control the heat pump function? Oh and thanks for posting this. Brian

[pickerdd]

Thanks for info on updating your Armstrong AC. I would also appreciate detailed info on how you upgraded your AC. It's something most of us with these AC's will want or need to do at some point.

I've heard the same thing as others that the Armstrong AC was a well built until worthy of fixing instead of tossing out. Great info. Thanks again.

[Jammer]

Excellent work and a worthwhile project.

I see you have a vacuum pump in one photo so I assume that you perform refrigeration work frequently. Most forum members do not and so would have to have the sealed system work performed by a technician with the applicable license and tools.

I second the request for part numbers and sources for hard-to-fit items, particularly the fan motor and compressor.

I wonder whether there are compressors available that will fit without a cover modification and the attendant loss of vertical clearance. Perhaps from another supplier or in a slightly different size?

Again, excellent work and photos.

[jmpratt]

You asked for it, so here's the details. First, Autozone has vacuum pumps as free loaner tools. Whenever I need one, I just go to Autozone and get it. Call ahead because they might not have one at a particular store. If they don't know what you're talking about, it's on the place mat on the store counter that shows all the loaner tools.

There is a direct replacement reciprocating compressor, the Tecumseh AK111AT-004-J7. This page has good info on doing a direct replacement. Bay Breeze Compressor Replacement Use of this compressor will not require any modification to the A/C cover. I used a Matsushita (Panasonic) 2P19C3R126A-SA. I wanted to use a rotary compressor for better efficiency and noise reduction. It is much taller, therefore I had to modify the A/C cover. My replacement compressor had 1/2" and 3/8" connections, so I had to use reducers to get the cooper to fit. In the end, I don't think it makes much of a difference. If replacing the compressor, you may want to consider buying one that for R-134A vice R-22. It may not be as efficient as the R-22 system, but getting refrigerant would be easy. If you really wanted to get into it, you'd need to get into some reference books to see how long the capillary tube would need to be to get the proper pressure differential for R-134a. You will need to get a new start and run capacitors per your compressors instructions. Of note, rotary compressors don't need start capacitors. R-22 is available on eBay.

The fan motor was easy. It's a GE 5KCP39DG5826ET, which is Grainger part # 3M783. Grainger says it's discontinued, but you can still find them online. There are many motors that will work, but they need to have a NEMA Frame 48YZ so it will fit. This one has three speeds, so I use the highest and lowest. Be sure to check the rotation direction BEFORE you cut the shafts to length. I didn't, so when I first installed it, the fans turned the wrong way! I just had to flip the motor over and use a shaft coupler to make the shorter shaft long enough. You'll need a new run capacitor per the motor's instructions.

The correct bi-directional filter/drier is a ALCO BFK-052s. I couldn't find one cheap, so I used a BFK-8255 which was a little larger and I had to use reducers on both ends to fit the 1/4" copper lines. If you don't make it a heat pump, you don't need a bi-directional filter drier.

The tricky part is the reversing valve. It was difficult to find one for such a small system (12K BTU is equivalent to a 1 Ton A/C). I used an ALCO RVS1-F34 reversing valve. I couldn't find one that had the correct sized connections. The TAC-110 has 1/4" and 3/8" copper lines. This valve has 1/2" and 3/8" connections, so I used some reducers to make the copper lines fit. Plumb the reversing valve so when it's not energized, flow goes from the compressor to the indoor coil (heat mode). When the valve is energized, flow should go from the compressor to the outdoor coil (cool mode). Also, ensure the reversing valve you use has a 24 VAC coil.

If you make it a heat pump, you'll need a new thermostat. Also, you'll need at least 5 conductors in your thermostat wire (for a single speed fan motor). If you get a thermostat that can control a multi-speed fan, you'll need 6 conductors. My '69 Ambassador only had 4 conductors, so I had to drop the ceiling and run a new thermostat wire. When buying a new thermostat, you'll only need a single-stage thermostat and it doesn't have to have "emergency heat". The conductors are for: 1) 24 VAC supply, 2) 24 VAC return, 3) compressor on, 4) reversing valve control, 5) fan on (hi), 6) fan on (lo).

You'll need a MAPP or acetylene torch to get the copper fittings on the TAC-100 apart. They are silver brazed and my propane torch couldn't get the stuff to melt. For reassembly, I used Stay Brite #8 silver solder which worked fine with a propane torch. Use flux and clean connections.

You can get replacement fan blades for the outside fan from MSC Direct. It's a 14", four-blade, 23 pitch, counter-clockwise fan.

That's most of it. What did I forget?

[ventport]

Very informative and well written. Thank you.

[Aage]

Fabulous write-up! Thanks very much for you time in doing that, it makes it a lot easier to understand.

[nmbosa]

That is an awesome write up. Nice work. I hope others can use this to rejuvinate their Armstrong AC's.

[loechli]

Great info exactly what someone needs to keep a good airconditioner running.

I have a 1972 international with Armstrong tr 21-12.
Has anyone found compatible parts for this system? IE compressor etc.

Steve

[jcanavera]

I guess my curiosity question regarding converting this A/C to a heat pump unit is how you handle the potential of icing on the external condensor? While not perfect, the current Penguins that A/S uses have a defrost cycle built into them which reverses the system back to A/C mode (along with shutting down the fan motor) when the heat pump runs over a certain amount of time. This causes the external condensor to get warm and melts any ice on the fins. As one who has experienced icing during cool wet weather, it becomes pretty important to do this if you are in high humidity climes. Once iced over, the heat pump output plumets.

Jack

[jmpratt]

Jack,
That's exactly what you'd have to do with this to defrost it. Usually the defrost cycle is controlled by the A/C electronics in the condenser unit. To defrost this one, I'll have to manually turn the thermostat to cool for 5-10 minutes every hour. Luckily, right now I live in the desert.

What I might do is make my own thermostat with a microcontroller that I can write my own program for. That would let me build in a software controlled defrost cycle based on outside air temp or put some kind of sensor on the outside coil. I was also thinking about adding in the propane furnace. That way the a/c will keep the inside cool, the heat pump will kick in for moderate temperatures, and the furnace will turn on when it gets too cold for the heat pump to work effectively. That's gonna have to wait a while until I catch up with some other projects.

[jmpratt]

Steve,
Open it up and get the model number off the compressor. It might be the same as I had. Either way, you can google it and find a replacement.