novakedy

I have another post about upgrading my stereo, but this issue is more specific about the A/C module as part of the whole upgrade so I made a new thread.
I have the 1995 Toyota Celsior UCF21, Type-C with the factory GPS and non-Nakamichi sound. As part of swapping the large multi-vision display/all-in-one module with an aftermarket radio, I need the A/C module. First, I purchased one that belongs in the 1995 Lexus LS400. When I plugged it in to test for operation, everything on it worked just fine although this was the incorrect part, as at the time I did not know that the electronics in the 1995-1997 Celsiors are near equivalent to that of the 1998-2000 Lexus LS400 (it also didn't fit properly). So I went on Japanese Auction and purchased one that was actually meant for the 1997 Celsior (so the passenger/driver side buttons match) which I believe to be the correct part (55900-50260). Apart from fitment, the main difference appears to just be that there is a clock on this one and build materials appear to be a little nicer. All of the plugs are exactly the same. Here is the one I purchased


A/C Module

After plugging it in with no key in the ignition, the clock displays perfect with no issues. When the key is turned to the ACC position, the amber front defog light blinks. When the car is in ON and is actually started, the clock begins to pulsate and so do all of the lights on the dashboard. At no point do any of the buttons function and actually turn on the A/C. Here is a video that I uploaded to youtube (note: watch in 720p or less as 1080p causes the video to white out for some reason)

My first thought was that the module I ordered was faulty, since the first one I purchased was not (even though it was for a different model car) and my stock multi-vision display controls work flawlessly. So I took the new module apart and very carefully inspected all components on the boards. Everything looks immaculate: no leaking capacitors, charring, or broken leads/wires/components that I could find with all plugs making good contact (this may be time to mention that I work with sensitive electronics for a living, but have little experience with car electronics specifically).
Now my next line of thought is that maybe my ECU is bad/capacitors are leaking OR that my ECU is not of the right model year for this A/C unit to function properly. I've read through the very large stickied post for the leaking capacitor issue and noted that I have in fact experienced some of the symptoms on the list, namely:
-transmission jerks from 1st to 2nd gear, and kinda slips from 2nd to 3rd
-speedometer not working reliably
-tachometer not working sometimes
-A/C going into reset with flashing front defog light (but in this case, ONLY for the new module)

Looking further on that post, I believe to have the "89661-50241 95.01-96.08 for UCF20" as my car's date of manufacture was July 1995, but I have not pulled it out to verify myself at this time. Listed just below that is "89661-50380 96.08-97.07 for UCF20 Can be used for models manufactured between 94.10-96.08 to improve the engine halt problem." which, I have also experienced once after doing some more digging into that issue. Once that happened is when I started doing research on the ECUs and trying to find one at a reasonable cost. As luck would have it I actually found one in great shape for much cheaper than I can find on eBay or anywhere else. My plan was already to install new capacitors and swap them out (I can see that one capacitor has already started leaking on the new ECU, but I haven't swapped them all out just yet).

Before I go ahead and start ripping apart my glovebox and dashboard, I figured I should ask here, would it be a good idea to swap these ECUs as-is (without new capacitors) to see if this is where my issue lies for the A/C module or is there some other kind of issue I should be looking for that I'm not finding on the threads here? Again, not sure how often people go around swapping ECUs so I don't want to make a mistake that might break something. Any help is appreciated!


Update:
Swapped ECU anyway. Same symptoms. I have determined the A/C unit to be faulty, though I cannot explain why as it looks to be in perfect condition. That being said, I did in fact have the 89661-50241 in my Celsior, and upon inspection it appears to have NO leaking capacitors. Additionally, the new ECU that does have one slightly leaky capacitor that I installed in my car seems to have weird throttling and gear shifting going on, so I will likely replace all the capacitors on both ECUs and determine which I like best..

Update 2:
Lesson learned: don't put leaky capacitors in your car knowingly. Car shut off and subsequently went into crazy limp-home mode when turning it back on. Must re-swap ECUs...