Even though the start Cap "tests" O.K., The relief hole in the top is open, so I will replace it with a like capacitor from Grainger ($8.00). I'll post P/N when I purchase and check to see if actually works.
I was getting goofy continuity readings on the start relay, so I decided to open it up. Check out the relay that I am the proud owner of...
The Service manual, (yes I have a copy PM me if interested) shows the relay as P/N 1890A13. The relay has General Electric and 3ARR3 K3S2 marked on it.
Has anyone changed this relay out with success, and do you have a good P/N and source?
I'll take it with me when I go to Grainger tomorrow. Once again, if I have any luck, will post results.
Thanks again to all who have got me this far. If this fixes the problem, and the a/c works, I'll have about $40.00 invested, and that includes a moisture proof enclosure to place these two components in.
Scott where did you get the manual?
Why not scan and post it (or link) here on site like someone was good enough to do with the later model manual.
Keep us posted with your results. Sure hope it works.
Armstrongs are awesome for their duration. Just think what other item could set up there in the elements for 40 years and keep on tickin. Not even a Timex.
Thanks a million! Do you happen to know what the current p/n is, or do they have the cross reference manuals on site?
Thanks again,
There are several different relay's that you can use.
Basically the start relay is a SP normally off device. (single pole)
The two big factors is the coil voltage, which in your case is 24 volts AC, and the currect carrying capacity of the relay terminals. As I recall it's something like 18 amps.
Scott,
From the picture your relay got wet and shorted out and that's what cooked it. It took less than 30 seconds to fry it probably.
Continuity is a goofy thing with relays. When your Thermostat calls for air it puts 24V to your relay and it snaps, which then makes connection to start your AC and you will have voltage across two contacts. . So when you do continuity on a dead (no volt) you should have continuity across the other side only. Going from memory now. It is easy to test with VOM. Disconnect the wires going to the AC and turn the thermostat and find the 24v from Thermostat. Hook the wires to the relay and you should have 24v going to the AC unit.
The relay part number I have is 1890A13 from the Armstrong Service guide. The fan relays (2) is part 237-07. One for low speed and one for high speed.
I believe you can use any relay with the correct number of terminals and as long as it is rated for 24v and as Andy states heavy current draw. The Granger catalog shows a bunch with descriptions and the part number may not be the same.
I would be interested in the service manual if you can PM it too me.
Good luck,
Gary
Give me a day or two, and I'll post it on this thread. That way as suggested, all will have access.
This relay is not a contactor relay, it is a potential relay. It is a separate relay, not the low 24vac relay. I believe it is designed to engage when there is no (low) voltage across it, and disengage, based on the back voltage (EMF) that the compressor coils generate when spooling up to speed. There are only 3 wires going to this relay. It removes the start capacitor from the circuit, when the motor in the compressor is at about 3/4 of full speed. Most motors today have centrifugal switches that open up when the armature spins so fast to do the same thing.
I know of an appliance store in town that does A/C and heating work. I will try to get there today, and see if they have any insight.
Thanks to all,
__________________
Scott
I have a picture of my Airstream in my wallet, and I'm sitting on it...
The Replacement Start Capacitor was purchased at Grainger. The capacitor is P/N 2MEP1, Dayton is the manufacturer. It is the same physical size as the old cap, but this one is rated for 330 volts, rater than 220 volts, which was the original one. I could have had them order a 220 volt, and saved about $3.00, but they had this one in stock,and for those of you that want to use the same enclosure, the new 220 volt one is a bit smaller in diameter than the original. If you buy the one I did, it fits in the stock bracket, being the same diameter as the original. This is O.K., you can go higher with the voltage, but don't go lower than the rated voltage. The original cap was 130-156mf and the new one is 130-158mf, also within allowable tolerances.
Now for the potential relay. I searched high and low, several hours, over a couple of days, to no avail. I finally ended up in a A/C wholesaler supply warehouse (G.W. Berkheimer Co., actually a big chain of stores in the Chicago area). I told my tale of woe to an older guy behind the counter, and he had the answer. The relay I was given is close if not the exact same physical size as the original. The manufacturer of this relay is "SUPCO". It is called a "Universal Potential Relay". Manufacturer's P/N SUPR 418-146-0242. Berkheimer's P/N 94847. This relay wires exactly, wire for wire, the same as the old relay, so it is a easy install. Where the original relay uses back EMF (tastes the voltage level of the compressor windings) this new Universal relay has a timing circuit that disengages the capacitor after a given time, to do the same function as the original.
I have attached a couple of pictures to show what the install looks like. It is, I believe as close to original as you can get today. Like I said, mine was damage due to moisture. This is only a temporary install for me. I am going to replace the enclosure, with a weatherproof one in the next couple of weeks, but this will get me through the holiday weekend, and was good enough to test the circuit with. Now, it was only in the mid sixties today, but I did hear the compressor kick in, and ran it long enough to feel the lines at the compressor feel hot and cold, so I believe I can report that the new parts do the job. If not, I'll report back after this weekend at the campground.
Bottom Line: New Capacitor, $14.03. New Relay, $16.96. A working A/C on a mid 90's day at the campground, Priceless.
Note: At least in Illinois, Both of these places I went to, Grainger and Berkheimer, are "wholesalers" and you have to have access to a commercial account to purchase from them. As practice, they do not sell to the general public. I was able to puchase these items through my employer's account. Get creative... ... as long as they have a valid business address, they will sell you the parts.
I know I promised a copy of the service manual for a TR21-12. Bear with me. I'll post it next week, as soon as I can get time to figure out how to do it.
Best to all,
__________________
Scott
I have a picture of my Airstream in my wallet, and I'm sitting on it...
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