What part is this window AC board

Thread Starter

Chrisg44

Joined Aug 4, 2022
3
Window air conditioner started turning on beeping, running for about a second and then turning off. Looking online it seems it’s the circuitboard that controls the unit, not the compressor. This blue component had almost like a dry liquid connecting two of its pins, along with now a coating around it. So I’m hoping changing this part will return forward to good functionality. Anybody know what this is?
 

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sagor

Joined Mar 10, 2019
714
It appears to be some type of "resonator", in lieu of a typical crystal. The label XT1 implies a crystal.
I doubt that is your problem...
 

Thread Starter

Chrisg44

Joined Aug 4, 2022
3
It appears to be some type of "resonator", in lieu of a typical crystal. The label XT1 implies a crystal.
I doubt that is your problem...
what could it be. I see dried shape on board around it and there was a dried clear substance between 2 of the pins, looks like something leaked out. Read some of these resonators have built in capacitor, could that have leaked?
 

panic mode

Joined Oct 10, 2011
2,215
i agree...

that looks like conformal coating.

also the resonator/crystal is used to generate clock for some MCU. without clock, MCU would be completely dead and nonresponsive. the fact that unit runs "something" ... responds to user input, does some timing (1sec or so), then does something else clearly shows that MCU is operational so clock circuit must be working.

chances are that something else is not right. based on info shared thus far it is unclear if the problem is on that board or not.
 

panic mode

Joined Oct 10, 2011
2,215
btw. when taking board pictures, try to also take full image of front and back.

that board looks seem to be just control panel (button panel). there are visible no power components etc.

control panels may be suspect on any device that deals with water (ac unit, dishwasher etc.) or any other contaminants but that board looks nice and clean.

major suspect is anything dealing with power (fuse, relay, triac...) as those components are stressed the most.
 

ronsimpson

Joined Oct 7, 2019
2,250
XT1 = crystal or resonator.
The symbol on the PCB is for a crystal.
There is a microprocessor on the other side of the PCB. They usually need a crystal.
1659714524739.png
1659714586863.png
1659714716424.png
 

Sigma229

Joined Apr 17, 2019
34
Hello,

I would like to see other side of the board like others said.
I would bet one of the chips on other side is faulty or many a loose solder connection.
Or depending on age of unit the buttons could be faulty and one could be stuck depressed.
I cant see the Crystal causing what you said is happening.

Grab multimeter ant test the switches and inspect the traces and solder points.

Hope you figure it out.
Sigma
 
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