Portable Aircon problem - Any help REALLY appreciated...

[MrShades]

Sorry guys - I'm trying to fix / fault trace my home aircon unit and found your interetsing looking forum. As I'm out of work right now I've got plenty of time to play with this thing but little cash to fix or replace... and having a pregnant wife complaining about the heat isn't helping!

Anyway - I've got one of those damn heavy "Portable Air Conditioner" things in the bedroom (bought from B&Q - called a WA-12000R), that used to work well and get the temps down reasonably well. It's not working quite as it should and I could really use some help trying to fix it (as I mentioned, made redundant a few months back so can't just go and buy another!)

When I turn it on it fires up normally (I've got the back off it so I can tell roughly what's happening). Excuse the laymans language... hopefully you'll get my drift...

Both exhaust and room fans fire up normally and I set the unit to max fan speed and "cool" - and as per normal after a few seconds the compressor kicks and fires up.

At this point the cooling rad starts to get cold (the pipes at the bottom of it and the rad itself at the bottom are pretty cold to the touch, and it obviously gets closer to ambient temp as I move my finger up the rad). The compression/exhaust rad gets hot to the touch, over much of it, though warmer towards the top, and the exhaust air blows hot.

It runs like this for a while... 30 mins / 45 mins I guess... all the time the cooling rad gets cooler and the exhaust rad gets warmer... as I'd expect.

Then it stops cooling, and it appears that the compressor just stops (you can hear it stopping). Not because it's hit the set temp (16c!), but just for the heck of it... The rads both start returning back to ambient temp and the exhaust air cools down to ambient also.

If I turn it off at the mains and leave it off for 15 / 30 mins and then turn it back on again it runs OK again for a while, and then the same thing happens.

Fortunately there's a wiring / system diagram on the back of the thing (below).

The two M's (fans for cool air and exhaust air I guess) are running fine... it's the C (compressor I guess) that's playing up. It obviously works (some of the time) rather than just being knackered itself - so my first question is, what is the 25uF capacitor doing in here?

Is there a chance that it's the capacitor that's failing/failed, and could it do so like this, after a while (as it 'heats up').?

Any idea what tests I could do with a DMM if I could get to the cap / compressor (working on getting all of the plastic covers off the damn thing now!)

Any other hints and tips, given the diagram below, on what the problem could be - it looks like a pretty simple setup and it does appear - literally - to be the compressor stopping that's causing the problem.

Any and all help or advice REALLY appreciated.

Shades

Aggg - I can't post the image as this is my first post...

Have a look here then:

homepage.ntlworld.com/mrshades/IMG_2870.JPG

http://homepage.ntlworld.com/mrshades/IMG_2870.JPG

[Gary]

Take it outside and hose down the coils (rads). You are not getting enough airflow through them due to the dirt build-up. Clean the fan blades, too.

Let us know how it works out.

[MrShades]

Thanks Gary - really appreciate the quick response.

Couple of quick follow-on queries...

1. Airflow seems to be OK, both from the interior and exterior fans (ie cool air inside and hot air being belched outside), though I'm guessing that given your reply there is possibly some form of cut-out on the compressor that will stop it operating if the coolant cant be sufficiently cooled by the exhaust / compression coil (ah, new terminology!)?

(A quick, "Yes, there's a thermal cut-out on it" will suffice ;) )

2. If that's the case, and I did (when I removed the back cover) remove A LOT of dust (more like the lint that acculumates on a tumble-dryer filter!) from the compression coil - am I primarily looking to ensure that the compression coil is as clean as poss?

3. What about the electrical components in the unit? I guess most of the 'plumbing' stuff is in the bottom and the electrical/electronics in the top - and if clean it outside and leave it to dry out for 24hrs or summut I should be OK...???

Hopefully you'll have cracked it - though some confirmation of the above points would be really useful, as I DO like to understand what's going on rather than just dumbly doing "stuff"...

Many thanks

Shades

[Gary]

It's not actually a thermal cut-out, but close enough. As the condenser coil (hot rad) gets hotter the pressure inside the coil builds up. The compressor pumps against that pressure and the energy consumption increases, until it's internal electrical overload switch kicks out.

Keeping both of the coils clean will reduce your electric bill as well as keep the room cooler.

Good airflow is crucial.

[MrShades]

OK... have taken it outside and hosed in down! Quite carefully I must admit... and some what cautiously...

However, the coils - esp hot one - now look significantly cleaner so hopefully that has done the trick. Can't easily get to the fans, but the output from them seems pretty good anyway. If I could figure out how to easily get the sides and front of the flippin' thing I may have had a go...

... unless the water I was spraying through the rads has also 'cleaned' the fans a little as well. Hope so!

Right now I've let it drip dry, have emptied the internal drip trays and I've left it sat in my conservatory to dry out, and will leave it overnight for the sun to get into it tomorrow morning and properly dry it internally. Will try and fire it up again tomorrow pm once I'm happy nothing electrical will fry...

Thanks again Gary - will report back once tested.

Shades

[Gary]

You might try the fan only setting. If the fans work, the air movement will dry the rest of it out pretty quickly.

[MrShades]

Well, I left it to dry out last night and then tested it - the 'cold' pipes looked to be frosting up nicely and the cold coil was getting colder than previously - and the hot coil wasnt as hot as previously and the exhaust air/tube wasn't getting anywhere near as warm as it was... which I guess is all good.

So - put it all back together, covers on, and staggered up two flights of stairs with the damn thing, and it's now been running perfectly in the bedroom all morning... just for testing purposes really.

I can't thank you enough for this tip Gary - as it's exactly what it needed - and one that I shall remember going forward... I'd already had visions of scrapping the thing - and it just shows how simple things can have serious effects.

If I'm ever in Florida, I owe you a beer...

Regards and thanks again,

Shades

[back2space]

REmember Mr Shades to keep your filters clean and coils cleaned regulary, the more the safety cut outs happen it shows that the compressor has been working very hard and this can overtime damage a compressor so make sure its clean!

[Gary]

Well, I left it to dry out last night and then tested it - the 'cold' pipes looked to be frosting up nicely and the cold coil was getting colder than previously - and the hot coil wasnt as hot as previously and the exhaust air/tube wasn't getting anywhere near as warm as it was... which I guess is all good.

So - put it all back together, covers on, and staggered up two flights of stairs with the damn thing, and it's now been running perfectly in the bedroom all morning... just for testing purposes really.

I can't thank you enough for this tip Gary - as it's exactly what it needed - and one that I shall remember going forward... I'd already had visions of scrapping the thing - and it just shows how simple things can have serious effects.

If I'm ever in Florida, I owe you a beer...

Regards and thanks again,

Shades

Glad I could help. :)

[Gary]

Both exhaust and room fans fire up normally and I set the unit to max fan speed and "cool" - and as per normal after a few seconds the compressor kicks and fires up.

Something else to keep in mind. Higher fan speed gives you more cooling and less dehumidifying and vice versa. If your room is too humid, kick it down to a lower fan speed.