Dehumidifier - compressor stall?

As a sealed unit I suppose there is nothing other than banging the compressor housing to reset the problem. Sometimes it will start properly so not permanently seized. Control board fuse of 1.6 amp (240V supply) has never blown but stall? current must be something more than 1 amp.

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N_Cook
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"N_Cook" wrote in news:k9q46v$e8i$ snipped-for-privacy@dont-email.me:

Got a hard start kit on it?

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Reply to
Ian Malcolm

Would that be inside the black plastic cowling to the side? otherwise just 2 wires going to the compressor + grounding wire

Reply to
N_Cook

ssor housing to reset the problem. Sometimes it will start properly so not permanently seized. Control board fuse of 1.6 amp (240V supply) has never b lown but stall? current must be something more than 1 amp.

If the 'off' time is too short, the compressors will often not be able to s tart into the back pressure that has not bled off yet. On my dehumidifiers that seems to take about 5 minutes. If the compressor is capacitor start [e xternal capacitor] then I would also check that the cap is not worn out. As you surmise, the motor current is not passing through that small fuse on t he control board. Even at 240V the compressor stall current will probably b e well over 5A since I am guessing that my 120V units are drawing 10-12A at start stall.

Neil S.

Reply to
nesesu

compressor housing to reset the problem. Sometimes it will start properly so not permanently seized. Control board fuse of 1.6 amp (240V supply) has never blown but stall? current must be something more than 1 amp.

If the 'off' time is too short, the compressors will often not be able to start into the back pressure that has not bled off yet. On my dehumidifiers that seems to take about 5 minutes. If the compressor is capacitor start [external capacitor] then I would also check that the cap is not worn out. As you surmise, the motor current is not passing through that small fuse on the control board. Even at 240V the compressor stall current will probably be well over 5A since I am guessing that my 120V units are drawing 10-12A at start stall.

Neil S.

++++

No capacitor seen.

2 wires to the compressor and under the cowling one wire goes to what I'd have guessed to be a bimetal thermal cutout attached to the compressor body, any markings obscured by metalwork. The other goes to one spade of a 3 spade terminal , at first sight looks like a 25 amp triac. 2 spades unconnected and ohmic between all 3, also connected to the main body. Marked QP2-22 , this being the nearest to a datasheet that I've found

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  1. QP2-22 Norminal resistance : 22O±2% Max voltage:350V Max current:8A Tripping time: 0.3?0.8S Reset time:
Reply to
N_Cook

That 1.6 amp fuse is just for the fan and electronics . I tried heating the QP thing with hot air but did not see any hint of resistance change. Put a .6R 20W in line to the motor and monitored the voltage over. In stall,

6amps initially and then dropping under the action of the QP and then a click as the cutout triggers. Then a matter of waiting until it clicks back. 1.1amp in normal running.

The other lump under the cowling , I can just make out some markings on the other side, Klixon on some metal and 4TM on the "kettle" white plastic so a thermal cutout

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Reply to
N_Cook

I've now seen the owners manual , from the owner. No mention of this stall procedure business. With the fan noise an owner would not necessarily realise that the start sequence can repeat multiply through this stall/lock out/ /cool/reset / start, rather than just start.

Reply to
N_Cook

This is a GET DHMD10/2 . I will monitor what voltages appear on pins 1 and 3 of the QP2 device and maybe add a suitably dropped neon (what are those other 2 pins for normally?) , so the owner can at least monitor , at switch on, how often the motor is stalled .

Reply to
N_Cook

I burrowed into an older working dehumidifier I could wreck if I needed. This is aWDH -101B with a P330MC PTC start themistor . There is a schematic for this in use in an LG NS30LAEG out there so I could see how the run/start circuit works. Unfortunately need to cut a corner off that PTC (not 3 exposed terminals , 2 others are sockets underneath for pins from the 2 coils) to expose the other terminal for the other side of the disc thermistor that connects to the run coil. Not enough discrimination in voltage drop to use a neon across the PTC. But a 240V neon from this exposed contact and the commoned feed to both coils at least shows when the cut out is activated as 240V across then. 4V (centrifugal switch ? so presumably induced voltage) across in normal running of the motor and 58V across in stall so the added indicator neon is out in those situations. At least then an owner knows that despite the fan noise , the pump is not running as this neon would continuously cycle 3 minutes on , 5 seconds off, ... Now to add a neon to the GET machine

Reply to
N_Cook

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