My name is Emma and I live in Abu Dhabi. First up, sincere apologies for hijacking your forum when I am not an engineer. I am just desperate and am really hoping you might be able to help.

We have a three-bedroom villa here with AC - a York International system with two types of thermostat (master and slave). (That's all the info I have!) The downstairs units all work fine, as does the one that controls the master bedroom. However, the unit that serves the upstairs landing and two guest bedrooms has always given off a horrible smell pretty much every time we use it. We moved in eight months ago and in that time have had the whole villa professionally cleaned twice (and seriously - guys in hazmat gear, entire house put under plastic, 12 hour job etc etc) and it never fixes he problem. We've had our maintenance people come out including an engineer, they said it would be a cleaning issue. The cleaning company have taken photos of all the duct work and units to show that it's not a cleaning issue and are saying they can't do any more. We've had a plumber out to check it's not a drainage/venting issue and they said it's not. Everyone is at a loss. But now the temperature outside is creeping into the 40s and we just can't continue to operate without the AC upstairs.

The smell is awful - like a cross between bad cheese, bit sewer-ish (hence my concern about plumbing) and feet. But what's really weird is that it doesn't always happen. I'd say it does 75% of the time we put that unit on. Sometimes it stars off fine and a ew hours later it's awful; sometimes it's awful straight away. We've tried monitoring what else is going on in the house to see if there are relationships but no joy so far.

I think we are going to have to move. And I really, really don't want to - we love it here and we're locked in until November anyway. The engineers the property maintenance guys send out are not AC experts and I can't help but think a specialist would be able to help us get to the root of the problem.

Please please please - any suggestions as to what might be happening or where we should tell them to look?

Thank you for your time