Mitsubishi MJ-E14CG-E1 Dehumidifier - Seized Compressor?

Please excuse the DIY question here...

The compressor on the above seems to have seized. Fan & electronics all work, but every couple of mins I here a click & hum, lasting a few seconds only. The compressor motor cannot be heard now. A power consumption meter shows a jump from 30w to over 600w, in time with the short attempts to start. To me, this suggests a seized motor.

If I dismantle it, am I likely to find anything I can try to fix? I'm thinking of a capacitor to change, or copper commutator or carbon brushes to clean/replace, or a start-up slot to turn the motor by hand, in case it frees it up?

If the answer to all the above is 'No', is there any larger assembly that I (or a paid service centre) is likely to be able to obtain at an economic cost? It cost £330 just over two years ago, paying twice the price of a cheapo unit, so I am a bit peeved at the prospect it could be junk just outside of its 2 year warranty.

Get it checked by some one with the correct test instruments, the compressor may well be seized or you may just have a faulty relay.
The compressor is a sealed assembly you cannot access the motor.
It would be your best solution to have some one check it for you.

Quote:

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Originally Posted by B G Scott

Get it checked by some one with the correct test instruments, the compressor may well be seized or you may just have a faulty relay.
The compressor is a sealed assembly you cannot access the motor.
It would be your best solution to have some one check it for you.

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Hi B G Scott,

Many thanks for the reply. I'm plenty used to mechanical/electrical fault finding & repair, which was why I was aiming to have a look myself. I've even found the Mitsubishi service/fault finding manual, but am non-plussed to see a pair of special 'set' screws, recessed down long holes, hampering access. As if modern consumer products don't defy economic repair often enough...

Re your comment on an electrical/relay fault, if either the coil or switch side was failed open or closed, it wouldn't explain the power draw surge (from 30 to 600watts, whilst normal running is 230w) in time with the relay clicking on/off? Would you agree that this can only be a stalled compressor?

I'm disappointed to hear the compressor is a sealed unit, but I quietly suspected that fact from what I know of fridges etc. Is there likely to be any startup screw slot which can be turned? Would you have any idea of the cost of replacement, given I guess the gas will also need be to be vented & replaced?

The last time I sought a professional quote for repairing some consumer electronics, the charge for investigating and preparing the quote alone was going to be over a third the cost of replacement with new, i.e. before the unknown potential repair costs had even been added.

I know, a throwaway age.

The start relay is mounted on the compressor terminals together with the overload, some times this can be one electronic assembly.
The fact that you can hear it clicking though would suggest it is Klixon thermal overload.
The excessive current draw will occur if the start winding is either stuck in circuit via the defective relay or the relay could also be open circuit leaving the compressor with just the run winding in circuit resulting in the rotor locked.
Before you do any thing else remove the relay from the compressor (it is pushed onto the terminal pins) and check the winding's, there are three pins on to which the relay connects these are the ends of the start and run winding's.
Check that you have continuity between common terminal and the other two terminals, then check the resistance of each winding.
The compressor motor is totally enclosed in the welded enclosure with no access for any physical inspection, I would not is the first instance assume the compressor is seized, I would suspect the relay/overload assembly.
You can obtain a generic electronic replacement for most small start relays from most refrigeration wholesalers

Quote:

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Originally Posted by B G Scott

The start relay is mounted on the compressor terminals together with the overload, some times this can be one electronic assembly.
The fact that you can hear it clicking though would suggest it is Klixon thermal overload.
The excessive current draw will occur if the start winding is either stuck in circuit via the defective relay or the relay could also be open circuit leaving the compressor with just the run winding in circuit resulting in the rotor locked.
Before you do any thing else remove the relay from the compressor (it is pushed onto the terminal pins) and check the winding's, there are three pins on to which the relay connects these are the ends of the start and run winding's.
Check that you have continuity between common terminal and the other two terminals, then check the resistance of each winding.
The compressor motor is totally enclosed in the welded enclosure with no access for any physical inspection, I would not is the first instance assume the compressor is seized, I would suspect the relay/overload assembly.
You can obtain a generic electronic replacement for most small start relays from most refrigeration wholesalers

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B G Scott - Many thanks for your detailed reply. I do appreciate it.

I got the case open, for the benefit of any future reader of this thread, the special/set screws used were a pair Torx T20, but with a raised centre piece so that a normal Torx bit wouldn't enter. The correct 'security' bit looks like a T20 but with a hole drilled down the centre. The next problem was that the screws are recessed a couple on inches down a tapered hole, so that it took some time to find a narrow enough hex bit driver, even then using padding (inside the hex driver's hole) and stick tape to just about reach the recessed screw before the driver locked up in the tapering hole. Thanks Mitsubishi :(

So once opened, I followed the service manuals check list. The 2A PCB fuse is OK. The Supply to the Compressor motor gave readings within those stated (C-R 28-31 ohm; C-S 31-35 ohm).

Down at the compressor, space to look is very limited. I can only semi remove the spring clipped cap over the contacts. There doesn't appear to be any relay down there, but a there is a round black component, loosely sitting upon the compressor. The underside is orange with 00307 printed in the centre. Two wires are attached. Is this a thermal cut-out as you describe? If it is one, it gave near zero resistance, so hasn't failed.

Back on the PCB, there is a soldered 12v relay marked 'Comp Relay' (Omron G5 CA-1A-E). The primary gives 667 ohm (whilst on the PCB; other components could only lower this reading), so hasn't gone open. But Omron's spec sheet says 360 ohms for this model, which is a concern re correct operation. Its switch contacts are open circuit as is to be expected at rest. I can only test this further by energising in circuit (with an external 12v battery, with unknown risks to other PCB components if powered this way) or else by removing from the board first.

Correction - Relay primary is nominally 720 ohms for this model, so 667 isn't that wrong, but switched contacts could still have failed?

Based on what you have kindly advised, would you agree that the motor windings appear OK, and that it is worth my while replacing the cheap relay component? Doesn't look a difficult PCB to work on. Obviously, the compressor could still be seized, but that probably means no economic repair.

Any further tests or advice gratefully received.

Correction - Relay primary is nominally 720 ohms for this model, so 667 isn't that wrong, but switched contacts could still have failed?

Well, I found a circuit diagram for a similar model, and from this decided it was safe to test the Compressor Relay whilst still mounted on the PCB. The only thing to watch is an anti-spike diode across the coil, so polarity matters. Anyway, a 12v battery and ohmmeter proved the relay was fine after all.

Looking at the circuit diagram, that only really left the Run Capacitor if mechanical seizure wasn’t to blame. Not your usual cylindrical affair, this small black box (about the size of a matchbox) didn’t show any outward signs of failure (like swelling or bursting), appearing to be metallised polypropylene. But an ohmmeter test showed permanent high impedance, which is not how capacitors behave when tested this way.

Finding a replacement wasn’t so easy. Whilst 8uF 450v run capacitors are everywhere in cylindrical form, ones small enough to fit the Mitsubishi’s electronics box are not. Eventually it dawned on me that these really belong to compact air conditioning units, which this small dehumidifier is related to more strongly than a fridge really. They likewise crop up for ceiling fans. Once found, it’s the old story of buying one from the Far East for a few pounds but taking a few weeks, or a courier type delivery from a supplier who holds stock somewhere out there but charges the earth to deliver quickly. I managed to find just one in stock with Amazon.

Well, all went together fine, and after turning on and waiting the default 2 mins or so, I heard the satisfying fridge like whir of the compressor kicking in! It is now merrily taking moisture back out of my steamy kitchen. Many thanks for the pointers received, I'm just glad that such a nicely made dehumidifier has been saved from an early grave for want of a component costing a few pounds.

So glad to hear that you have had success Roy.

However, the fact that you came back to report your actions and findings is really appreciated, thank you.

Hi All,

What a wonderful forum! I am posting to convey my thanks.

I am nothing close to an engineer, in fact, fly planes for a living(…) but your descriptions allowed me to fix the mitsubishi MJ-E14CG-E1 for a few euros (E3,65 to be exact).

The mitsubishi electric guys here (AbuDhabi UAE) had never seen one before and told me to buy a new machine and they cannot offer support here.

I did find the service manual and that, in addition to the information on this forum, allowed me to "Home fix" the dehumidifier compressor start fault.

Strolling through the Carrefour supermarket I could not believe my eyes, a Torx 20 with security hole in the home DIY section.. too good to be true. So, that solved the access problem with the deeply recessed top front face 2x security screws. A 10cm screwdriver shaft is absolutely sufficient.

Into the electrics box, and as per the attached, you can see the 8 micro farad capacitor was knackered. I didn’t bother testing anything else and headed off into the industrial area with said capacitor in hand. Nobody had the square box shape in stock, but cylindrical design only.

Better than nothing, I used a hacksaw to make it fit by removing part of the electrics box cover and internal moulding supports. The cylindrical capacitor on its side is a little longer than the matchbox design but otherwise fits snuggly into position.

Fearful of a fire, meltdown or explosion, I stepped back and put the system into test mode such that the compressor comes on immediately… The fridge-like sound came back, and, after a few minutes on the run a few drops of water came out.

My piano is safe now from the humidity; wood, glue moving and rusting strings!

During the interim with no dehumidifier, I did have to purchased a FRIGIDAIRE dehumidifier and it knocks the socks off the Mitsubishi. Albeit, it makes a huge noise!

I’ll keep an eye on the mitsubishi before trusting it to run when I am out of the house.
Finding this thread has saved me many hundreds of Euro. Thanks again to all of you for sharing the information and detailed instructions! Isn’t the internet a wonderful thing!

Few weeks later: Mitsubishi still working wonderfully. Almost constantly in fact :)

Picture of "New" and "Old" capacitor is included.

Attachment 14186

Dear jmacdonald,

Really pleased to hear my instructions proved so useful!

Internet forums like this have so often saved the day for me, that I could hardly not post what I found. Partly to help others, given anyone can find almost anything so fast nowadays, and partly in case I ever needed to repeat the repair and remind myself what I did years later.

Square capacitors to fit are easily found on eBay:

http://www.ebay.co.uk/itm/CBB61-8uF-...QAAOSwFqJWmSz2

The only catch being the delay from Hong Kong etc. I bought two for a few pounds after, just in case it blew again. These are slightly smaller, and need a plastic tag (for screw mounting) sawing off, but otherwise fitted easily.

Like you, I very nearly threw my Mitsubishi away, and am just glad I 'wasted' a couple of days on the internet and hunting down the right Torx security bits, which as you say, are easy & cheap to find when you know what you need.

I'd be interested to know why the Frigidaire was so much better though?

Anyway, very pleased to have helped someone else!