Water Noise Evaporative cooler

We have had an Evaporative cooler fitted for about 10 months it works fine, but the last day or 2 we have noticed a really loud whistle when the water is added, The water seems to be being added every 3 or 4 minutes (is this normal). I rang about the warranty, they are happy to come out but explained that if the fault is caused by water quality this is not covered under warranty and I will be charged $88.00 for the first 15 minuted and $20.00 for every 15 minutes after. As the unit is on a rather steep 2 story roof, I think it could take some time to diagnose and I fear I may be up for quite a sum of money if they decide it is not their fault.
I am an electrician by trade and have worked on hydraulics and pneumatics and feel fairly confident I could track down the fault myself, but I will probably void my warranty by attempting to repair it myself.
I am interested in the thoughts of people am I being paranoid thinking the repair company will try to make it my fault?
does anyone have any idea what the fault may be (I am guessing a bit of foreign matter or a washer stuck in a valve somewhere).
Is it likely I can easily fix it myself.
The unit is a Coolbreeze D125
I will be glad of any advice thanks in advance

There are two types of flush systems on swampies: constant loss or total dump.

If your system is a constant loss type, then the tap refilling @ 3 or 4 minutes intervals is normal. By "constant loss" I mean there's a small drain that constantly trickles to waste, the rate of trickle is usually controlled by a small set-&-forget tap in the better quality units.

With a total dump system, when the unit's switched off a solenoid valve opens and dumps all the water in a matter of seconds... and you generally know if it's one of these 'cos the dumping's not exactly silent. :roll: This system should only refill once at the start, when the system is turned on, and occasionally afterwards to replace evaporative losses. 3 or 4 minutes is way too often, unless you have a family of thirsty possums living in your swampy. :U

Of course, both types can be affected by water-quality... deposits in the tap seating or gunk building up in the drains can cause unwanted leaks or blockages in either the inflow or outlet.

Both types generally use ball float valves to control water flow, but sometimes the dump systems include a shutoff solenoid in the float valve assembly, which can be a pita to fix. (Easier to replace, more $$ for the mfrs. :~) Be warned: some of the dump valves run on 240VAC!! :oo: Old Breezairs were renowned for this, although I'd imagine that by now they'd all be lower voltage DC systems. I wouldn't stake my life on it though.

I can't speak for Coolbreeze... I don't they weren't a name in the game when I was slaving on hot roofs. Well... I didn't deal with 'em. I think, from vague old memories of hearsay, that they may've bought out CelAir? If so then it's probably a constant loss system and an easy job for you to fix & maintain. [fingers Xed]