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Old 07-12-2020, 02:22 PM   #1
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CruisAir unit dead

Smelled burning wire insulation then the breaker popped. 16 ton stowaway unit.

Inspection of control/ logic board showed black and purple wires on the TRIAC switch fried and oil leaking from the start/run capacitor. Fabricated new TRIAC wires and reconnected the circuit board. The control panel and fan work fine. Compressor and cooling pumps won’ start, although there is a “click” near the compressor when the cool button is selected. A second click occurs a second later.

Meter checks this morning show power to the black and yellow TRIAC wires at all times (cool button on or off). Nothing on the purple TRIAC wire. No evidence of power transfer to the cooling pump wires. (The shared pump works fine on the second AC unit.

I’m planning to purchase another TRIAC switch, a start/run capacitor and a PTCR. Any other suggestions? Can I bypass the logic board and jump start the compressor to eliminate it as a failure? Other than these things am I facing the dreaded logic/control board replacement? Is there a place that refurbishes them? I’m not capable of trouble shooting a circuit board.

All ideas much appreciated. Thanks
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Old 07-12-2020, 04:00 PM   #2
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Give Flight Systems a call. Their rebuild service for generator and air conditioning control boards is first rate.

https://www.flightsystems.com/rv-gen...r-service.html
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Old 07-12-2020, 04:20 PM   #3
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Thanks for the tip.
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Old 07-15-2020, 09:06 AM   #4
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There’s not an Hvac tech available for weeks in this area and I searched the internet for hours.

I want to bypass the logic/power circuit board to attempt a direct start of the compressor in order to establish whether it’s locked up. It appears that the thermal overheat switch and the high pressure switch are the only “protection” switches that could be malfunctioning in that circuit (other than the board itsel). If I jumper/bypass those two items (in the event they are stuck), and have a new capacitor installed, which wire on the compressor motor do I hook to the line power to see if it will spin?

The compressor has a black wire (via purple on the TRIAC switch) to the compressor C terminal, a pink wire from one side of the capacitor to the compressor “S terminal, and a white/red from the other capacitor terminal to the compressor “R” terminal. Would I also need to jumper the capacitor (in the event that something in the logic board is interfering?

If the compressor is dead, I’ll just purchase another unit. If it’s functional, I’ll send the board to Flight Sytems.
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Old 07-15-2020, 10:42 AM   #5
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Sounds like you are beating a dead horse. How old is the unit?

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Old 07-15-2020, 01:30 PM   #6
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The compressor being locked up wouldn't damage the board. So, I don't think there is much more of a risk of that now than there was an hour before the board failed.
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Old 07-15-2020, 03:01 PM   #7
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The AC was installed in 2005, but has only been used intermittently during Great Lakes summers. That might add up to a year or two in Florida terms. So I donít believe Iím beating a dead horse....just looking for someone who knows HVAC...
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Old 07-15-2020, 08:04 PM   #8
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This is really hard to debug with no service documentation and without the model number to try to find any.

There is often a schematic on the unit, on the control box, or inside the cover of the control box. If you can find that, scan it or get a good photo of it, and post it, I can probably be of more help. Alternately, if you can post the exact model I can look and see if any info is already posted to the web.

Beyond that, you might want to take a look at a tutorial like this to see how to test the compressor, if you are comfortable and feel safe doing that, following the proper precautions, etc:
-- https://www.lennoxpros.com/news/the-...ase-compressor
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Old 07-16-2020, 08:59 AM   #9
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Thanks for responding. I’m messaging from my wife’s phone and I don’t know if or how to link. But the wiring diagram is on page 20 of the on-line publication called “SMX II control systems (DX)”. The compressor is Cruisair model SXF 16/1-RMT. It is a “stowaway” unit (and the wiring at the top of the compressor is almost touching the top of the seat bench structure...inaccessible without partially moving the unit). The logic panel/box is remote and easy to reach.

The diagram glued to the inside of the remote power/logic box is M1010097G and is titled SXF5-16(C/CK) Stowaway compact with SMX control. It is the same as the drawing in the on-line manual referenced above with one exception...there is no optional hard start circuit depicted (and not installed on my unit).

I’m going to read the item you attached next. I’m not versed in AC,but have been reading a lot. One thing I’d like to nail down is that the wire colors on the power cables are the same convention for marine and household.

Best I can figure, to completely bypass the circuit board for a quick jump start of the compressor, I’d hook the feed for the C terminal directly to the black wire in the power cable, and the capacitor feed would be connected to the white wire in the power cable (with the rest of the capacitor wires to the compressor attached per the drawing in the diagram). Then turn on the breaker at the wall switch. If no start it could be a faulty thermal switch or a faulty high pressure switch/ circuit. In that case I don’t could try to bypass/jump those switches. If still no start the compressor is likely finished. (This unit does not have a low pressure switch). Am I on the right track?
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Old 07-16-2020, 01:47 PM   #10
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After reading the excellent tutorial, I disassembled the air delivery end of the unit so I could slide the whole assembly far enough to the left to access the compressor wiring and safety switches. Then I took ohm readings. The meter tended to “hunt” around but these are ballpark values when it settled down: C-R 0.9; S-C 4.3 ; S-R 5.1. I took multiple readings and CR plus SC never added exactly to SR, but they were in the ball park. I also checked the thermal overload and the HP switches and they each showed 0.3 on the ohm setting. So I believe that’s all good news??

Waiting on the new capacitor, TRIAC and PTCR to arrive. Still wondering if a direct start (bypassing the logic board) would yield useful info...
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Old 07-17-2020, 10:21 AM   #11
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Yep. Good news. That all tests goods. It is overwhelmingly likely your problem is on the board.

I was away from the Internet yesterday, but will have some time this afternoon and will see if I can find and look at the schematic.

But, U really see no reason to suspect the comoressor.
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Old 07-19-2020, 01:05 AM   #12
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I just went to look at that manual. But, I couldn't find what looked to be an applicable schematic. Can you paste the URL? You don't have to do anything fancy. Just cut and paste it into the message. If you want to post a photo of the schematic, hit the "Go Advanced" button then look for the paper clip, then "Choose File", then "Upload".
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Old 07-19-2020, 08:33 AM   #13
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This address should get it:

http://www.tropicalmarineairconditio...ets/L-2362.pdf

It also pops up using .../L-064.pdf in the same address

As Imentioned in earlier post, the correct chart is on page 20 (but without the hard start or low pressure switch).

Thank you again for the help. The new capacitor, PTRC and TRIAC should be at the post office tomorrow.
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Old 07-19-2020, 09:38 AM   #14
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No schematics in that document;-(
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Old 07-19-2020, 10:24 AM   #15
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Try this...Google “Cruisair P-967”. One of the pop ups is Dometic Southern Marine Supply Inc with a PDF document. The correct schematic is on page 21 of that 1100 plus page service document
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Old 07-19-2020, 10:47 AM   #16
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I took a photo on this I-phone...now letís see if I can attach it...

Click image for larger version

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Old 07-19-2020, 01:21 PM   #17
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Leaking Capacitor = Bad Capacitor

The fact that the op mentioned that the capacitor is leaking fluid indicates that it is bad. The compressor will not start with a bad start capacitor. The op's describes the unit clicking on start up and then clicking agin several seconds later. This is exactly what would happen with a bad start capacitor. Unit would try to start then go out on overload.

You can test a capacitor easily with an ohm meter. The capacitor should initially look like a dead short on the ohm meter. As the capacitor charges from the battery in the ohm meter the resistance will go up steadily to infinity (be sure to discharge capacitor by shorting it after making any tests).

Any other issues he may have are secondary.
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Old 07-19-2020, 01:43 PM   #18
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As I said, Iím waiting on the mail for the capacitor and a new TRIAC switch. The interesting thing that happened during the failure is that two wires between the Triac switch and the board got so hot that the insulation burned off (and one of them...the power wire to the compressor....actually burned through the wire at the board terminal). Iíd still like to bypass the board and jump start the compressor when I do get the new parts...then try a start with the board in the loop.
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Old 07-19-2020, 04:24 PM   #19
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It sounds like protection components failed. Is there a way to test thermal overheat switch? Here's a youtube that may help. With a bad cap, the compressor would try to pull maximum current causing thermal overheat. I give you credit for DIY as no tech available for weeks. I'm surprised that the circuit breaker didn't trip before the wire insulation melted. Major fire hazard. Usually breakers become weak and trip early. Very lucky there wasn't a fire.
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Old 07-19-2020, 06:23 PM   #20
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So, that is more of a wiring diagram than a schematic. But, based on what is there and some guessing, my guess is that your real problem is the one associated with the triac, not with the capacitor.

The capacitor seems to be a run capacitor that is shunted by the PTCR during start-up. In other words, the capacitor is used to phase shift the power to make the compressor run well -- but not to get it started. It appears that, the capacitor is effectively removed from the circuit by the PTCR during start up so that it doesn't limit initial current.

Based upon your report that the capacitor is leaking, it should be replaced. Caps can fail open or closed or add series resistence. So, they can do bad things. But, it is unlikely that this one is what is preventing start-up. Even if it were open or had developed resitance, the motor would likely still start, just not run well. And, if it shorted, that would likely be more dramatic. So, please do replace it. And, doing so might make things run better -- but I don't think it is the reason things won't start.

If you want, check to make sure the PTCR is very low resistance after the unit has been off for a while. This would show that it is, at least initially, shunting the capacitor and allowing full current to the compressor.

I can't quite sort out the circuit from the wiring diagram alone. It doesn't show all of the connections the same way a schematic would. And, I can't trace it from here. But, from the looks of it (and, again, I make no promises), the yellow wire on the triac looks to be switching the connection between the purple and pink wires on the triac on and off. The distal end of the wire is labeled GT (Gate) and the position of the terminal shown on the triac is a common one for the gate. Having said that I still don't recommend bypassing anything (.)

You already checked your compressor and found no shorts. If you really, really want, you can investigate the pump. How does the wiring going to and from it look? Does it have a fuse? Is it blown? Is it the right size?

If you want, and know how to do it safely, you can disconnect the pump at the terminals and check it -- via a switched circuit and a the right size over-current protection device. If it blows the fuse or breaker, it could be what ate the triac.

You might also recheck the wires connectred to the ones you replaced via that terminal block and otherwise and make sure none show any heat damage and if so, check what is attached to the other side of them.

I can't emphasize strongly enough that you are dealing with a 120VAC circuit with the ability to supply enough current to hurt you, start a fire, etc. Sometimes it is worth a service call, even once you have the parts. A lot of times, for jobs I don't want to do, I pre-order parts and have them on hand for professionals. It is the best of both worlds -- money saves by having the parts on hand and saving trips, money saved on mark-up, time saved by having things fixed faster -- and the honed judgement and skill of a professional.
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