AC window unit keeps blowing fuses

Hello all. I'll try to make this brief, but I doubt such a thing is possible.
I have a Whirlpool 24,000 BTU window unit that cools my whole house. I've had it for a couple of years, and it's worked brilliantly up until now. About a month ago, it started blowing fuses; it's an old house, still have old electrical system, fuse boxes, etc. At the time, the temp outside was mid-80's, so it's not like it was having to work overtime to cool things down. Anyway, I replaced the fuse, and about a week later, same thing happened. The problem escalated over the next two weeks, finally had to call a repairman.
He checked it out, said he couldn't find anything wrong with it either mechanically or electrically--the unit has its own 20 amp circuit, and at peak operating time was only drawing maybe 12 amps. Thought that the unit was having to come off/on too frequently, that might be the cause. He suggested I switch to power-saving mode, where the fan stays off until the compressor kicks in--in PS mode, compressor doesn't alternate quite as often. If all else fails, he suggested I have them install a "hard start device."
Unfortunately, PS mode is not an option; when the unit runs, it's loud, but it's white noise, so I get used to it being on. Having the fan alternate, especially at night, wouldn't work because the silence wakes me up (plus I'd stay awake, wondering if the unit was working still or had blown a fuse). That, and I've found that when the unit is off, bugs find their way into my house (another issue).
My only solution thus far has been to bump up the thermostat, which has worked for a couple of lukewarm weeks. But now it appears my cranky AC doesn't like that, either.
What do I do now? Do I call him back, have him install the hard start device? Could the problem be electrical, and if so, do I call an electrician? Or should I just empty my bank account and throw cash at the unit until it starts behaving again, like every other bleeding thing in this house?
Any/all advice is appreciated. Thank you for your time.
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nycknayme wrote:

<SNIP>
I assume you are already using some type of "Slow Blow" time Delay fuse.
Often, those old fuse holders OR the wire terminals will generate enough heat due to resistance that the fuse will blow from conducted heat rather than excessive Amp draw.
Look for discoloration of the fuse contacts or the lugs for the wire termination. If this is indeed the problem, it may take some kind of fuse/breaker replacement to solve.
Jim
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Does the fuse blow when the AC is cycling to on? Or does it blow at random time? The fan doesn't draw much current so I don't think PS mode is going to help.
Someone already suggested a slow-blow fuse. If that doesn't help, a hard start device may help. If I understand correctly, a hard start device is a capacitor to "buffer" extra power for the compressor when it cycle to on. When a motor load turns on, they can draw a very large current for a split second. If the load on the motor is heavier (let's say the bearings grease dried out), then this split second could become longer and more likely to blow a fuse.
-p

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Thanks to both of you for your advice--but I think I might have stumbled upon a solution.
Went to Lowe's to get another box of fuses--have been getting Buss 20 amp, time delay fuses--they didn't have any with a base that matched mine. Then I noticed there was a cubbyhole that had fuses that looked identical to the ones I have been using--same color, size, base. Only these were labeled "heavy duty," and the innards looked slightly different from the ones I'd been using.
I bought them instead, plugged them in yesterday, and so far, no problems--I even bumped down the thermostat, and they've been able to handle the load. I suspect that, last year, I might have bought the wrong type fuses for that circuit, 20 amp fuses that looked exactly the same as the old fuses, even said on the box they were meant for things like AC's, etc. This year, when an old one got blown, I started replacing them w/the new batch, and that's when the problems began...? Seems like a valid theory, at least. I'll give it a week. (crosses fingers) ;)
Thanks again for your help--I might still look into that hard start device if it starts getting cranky again.
Cheers, David
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I trust you didn't replace a 20A fuse with a 30A fuse? It would "fix" your problem alright, but you're putting the burden elsewhere in your wiring.
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That's right--30 amp. How'd you know that?
*sniff-sniff* Hmm, wonder what that burning smell is...
Haha, no, Peter, they're also 20 amp fuses. Sorry, forgot to include that in previous post. ..;)
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