The AC system can be searched in the archives. There is a great article by Steve Brotherton under the DIY tab at the top of the page. Steve also describes a method of using the A/C display as a diagnostic tool
'94 C220 Questions (Simple)
David C Klasse expands on that info at the thread ATTN: STEVEBFL.... Great Info Here!!!
A search for key words (C230, A/C, etc) will reveal other threads. Your symptoms occured on my 98 C230, and the A/C display trick indicated it was the Evaporator sensor MB Doc - diagnostic champ!
The cabin combo filters can be ordered for the best price at Partsshop via the 800 number at the top of the page. I use the Bosch which is both paper and charcoal for removal of dust and odors. The location, instructions, and frequency of replacement are found at the Bosch site http://www.bosch.de/aad/en/produkte/filter/innenraum/a_kohle.htm
. Click on the 'vehicle specific information'and then on 'installation locations according to various models' and a list of cars appears. Click on C180-C280 and an acrobat file of instructions for your car appears. They say a change frequency of 30,000 miles, but I do mine every 6-12 months.
Hope this helps.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E