Internal Fuse Blowing on Budget unit

[rubybree]

I'm based in Spain and had been asked by a customer to Vac out their newly (self installed) system. Its a budget make and he is a plumber by trade.

All pipework seemed ok, released the gas. switched on unit which ran for mins, by the time I got out to listen to the compressor, the power had shut down on the indoor unit.

The company that supplied it do not want to know. I looked at the internal circuit board and noticed that the internal fuse had blown (3.15Amp), replaced that with similar rating, ran it for 30 mins, all seemed ok.

Refitted indoor casing, tried again and fuse blew again. My question is, can I up the amp rating without causing much damage, bearing in mind my customer has already accepted he may need to scrap the unit.

What could be causing the problem? All wiring connections seem ok with no shorting marks. There is a earth protector on the main house circuit board

I've replaced the fuse again, twiddled the wiring and ran it for about an hour without any problems but just have a feeling that I'll be back.

Any thoughts would be appreciated..

[Brian_UK]

Sadly, if you buy cheap then you get cheap.

Could be a faulty fan motor or dodgy internal electronics.

[monkey spanners]

What does the fuse protect?

How much current is the unit pulling?

[rubybree]

I think its the internals as when the damn thing switched on after I'd replaced the fuse, it worked ok. I went through all the options switching off/on, hot/cold. I'd literally put the case back and was packing tools away when the damn thing flicked off again. I've run it for an hour up to now with case back on and it seems ok (crossed fingers). I must admit I've only fitted this make of unit once or twice before but they are not that bad usually (its a B&Q sister company). The problem in Spain is that most of the properties are holiday homes and only used 6-8 weeks a year and so people just want cheap.

[rubybree]

What does the fuse protect?

How much current is the unit pulling?

the glass type fuse appears to protect the main indoor unit circuit board, using a standard Spanish round pin plug (pre moulded) which also has earth but no fuse (which is normal in Spain). The main breakers are probably 10-16 amp. I didn't have a meter with me at the time, as I was originally only going to vac out the system and release the gas and so can't confirm the current used, but when the compressor did run, it didn't seem to be straining and everything sounded normal. Its been a day now and the customer has not rung back 'just yet'. I've only seen this once before and that turned out to be two comms cables arcing at a badly fitted join, but this installation seems to be a very simple 'Back to Back', cable seems one piece and sheathing appears to be have removed correctly.

[install monkey]

what ever was shorting may have now cleared with repeatedly replacing the fuse, could also be moisture from humidity or condensation on the compressor causing the terminals to arc occasionally

[rubybree]

Thanks for your replies. Hopefully its not going to rain in Spain for a while now Summer is kicking in.....