WS Fiesta aircon stinks and fails at low speed

[BruceT]

My 2009 WS Fieta Zetec is a fantastic car. Recently the air conditioning has started failing and stinking.

First symptoms - after starting and switching A/C on, the windows fogged up before exiting a car park (external temp 25-30C).

Lately - on hot days (35C+) the A/C could not cool the car and eventually just blew hot air in my face. This happens at low speed in traffic jams and when stopped at lights. Once underway it works again, probably due to better airflow over something (what? condenser, radiator?)

On one hot day (38C) in stalled traffic the car overheated (warning light) - I was on approach to the Harbour Tunnel and there was no break down strip. The A/C blew very hot air in my face and the external temp indicated 45C, hotter than it really was. I switched off the A/C, wound down windows and switched off motor when stopped. Once underway again for less than a minute (in the tunnel) the overheated warning light sent off and the ext. temp. dropped to 38C. The aircon worked fine about 10 minutes later, provided I was driving at 60 km/h+

Air coming from A/C and even ventilation with no A/C now stinks, a bit like rotten egg gas - like sports clothes that haven't been washed for a month.

I usually dive with A/C on (with recycled air) and windows up for three reasons - to reduce traffic noise, reduce humidity (I sweat heaps) and to listen to MP3 podcasts on Bluetooth. So the A/C has been used most of the 70,000+ km I've had the car.

I've checked Big Damo's posts and I do have a filter, but not the "T20 torx bit/key" to replace it:
http://www.fordforums.com.au/showthread.php?p=4727552

I'll get the gear to replace the filter and try Trumpy73's advice:
http://www.fordforums.com.au/showthr...hlight=air+con

Should it get service professionally? Does anyone recognise the symptoms?