Whirlpool PACF212HP W portable air conditioner, upper fan only turns slowly.

[spleenharvester]

I just acquired this portable aircon, history unknown. Its behaviour is quite strange:

• When turned on and placed into cooling mode, the upper fan (cold air out) just spins slowly. The compressor and lower fan do not run.
• If the device is then placed into heating mode and then back into cooling mode, the lower fan and compressor kick in and start cooling, but the upper fan still only spins slowly.
• If the device is placed into fan-only mode, the upper fan does not respond to low/medium/high speed toggles - just keeps running slowly.
• Display and buttons all behave normally aside from the malfunction.

Here is what I've done so far:

• Replaced all the caps except the big filter cap (they were junk AiSHi caps). No change in behaviour.
• Checked +5V, +12V, +15V and +18V rails referenced to appropriate grounds - all within range
• Noted the middle opto is not activated. If injecting 1.2V into pin 1 of the opto the upper fan motor makes a revving noise but the fan doesn't actually increase in speed
• Measured the upper fan voltage outputs - VDC = 330V, 15V = 15V, FG ~ 10V, VSP ~ 3V - regardless of whether the speed toggle is set to low, medium or high

Drawing a blank with this to be honest, I have been tracing the whole board trying to find any readings that correlate with the low/medium/high speed toggle but can't seem to find one. I am starting to think the main control IC is hosed but I haven't had any luck tracing the pins just yet, partly because I am having trouble removing the conformal coating. Pics attached - note the iffy looking solder around the optos is just from me lifting the legs etc, I had a good up-close look at the board before I started working on it and did not see any abnormalities. The main components include two SAP2003SC transistor arrays (one seems to control the small vent cover motor and the other controls the relays), a 48 pin unknown control IC, and an INN2063K flyback switcher.

Thanks

[spleenharvester]

Update - I've since disconnected VSP from the upper fan and injected voltage into it from a bench supply - it does respond to voltage increments so it appears to be a fault in how VSP is generated

Update 2 - the lack of VSP appears to be a GPIO fault, I've ruled out everything downstream of it. I can activate the fan by pulling BC807's base to ground through a 10K but it still doesn't seem to respond to low/med/high inputs and I can't figure out what is supposed to be generating them? Another dead GPIO pin perhaps?

[spleenharvester]

Final update, gave up trying to restore speed control and just installed a permanent 10K to logic level side ground from the base of the BC807 to keep the fan at maximum all the time (in this VSP system 3V = low, 5V = med and 7V = high). Machine now works perfectly aside from not responding to low/medium/high toggle

[stj]

the gpio was probably a pwm output.
what chip was it?

[spleenharvester]

the gpio was probably a pwm output.
what chip was it?

I've no idea unfortunately beyond it being the MCU, it was covered in conformal coating and had a label slapped on the top, etching seems to be gone now.

I had the motor out on the bench and confirmed 3V/5V/7V on VSP corresponded to low/medium/high, and that injecting 1.2V across the opto created 7V on VSP. But the cold side fan still seems to be weirdly slow? Faster but still disproportionately slow compared to the hot side fan which sounds like a jet taking off. The only other pins on the fan connector are VDC (=~330V), 15V (=~15V), GND, FG (=~10V) and VSP (now pulled to 7V). But unless I'm missing something it seems like FG is just a feedback signal to the MCU, either to monitor or to modulate VSP with, so I'm not sure where the problem is.

Part of the issue is that I've never seen this unit working and cannot find any videos of it so have no idea what it's supposed to behave like

[CapLeaker]

Does it have a programming port?

[spleenharvester]

Does it have a programming port?

It has that three pin unpopulated spot marked 5V/flash/GND, I assume it's that if anything but I have no idea what kind of interface that is. The only other thought I've had is maybe the frequency generator pin (FG) has something to do with it. They went to the effort of putting an opto in to communicate with the logic level side but I can't seem to figure out what the purpose is, the machine doesn't behave any differently with it unplugged and VSP seems like it's supposed to be controlled entirely from the display interface

But then again I ran it for a while last night, the exhaust fan feels extremely powerful up close but after the vent hose the pressure is probably similar to the cool side fan, so maybe it is just like this by design. The only other portable aircon I've had seems to use a turbine type design where both fans are driven by the same motor so I'm used to both sides giving a ton of airflow. Without the exhaust and compressor running I'd say the noise level of the cool side fan is about 25-30db

[spleenharvester]

I've had it running overnight, it is struggling to keep the room colder than 3 degrees lower so there is definitely something wrong with it, my 7000BTU black and decker unit runs rings around it. I don't think it's an issue with the refrigeration loop as the air it does put out is very cold, although the compressor runs almost continuously. I think there has to be something wrong with this cold side motor internally.

EDIT - Solved. It had a loose coupling screw in addition to problems with the VSP circuit. Tightened up with some threadlocker and she sounds like a jet taking off now. :-)