These codes are listed in the Haynes Manual. It would be worth it for you to buy one...commonly found now at Autozone and other auto parts stores for under $20.00. The 2-3-4 code means "Floor/defrost damper motor position sensor shorted to earth." This could mean a number of things. 4-1-1 means that your blower motor is not working..."blower fan seized or drawing excessive current." These parts are not cheap but also not excessive. The blower motor is located on the passenger side under the glovebox/kick panel area, but I would not recommend that you service this yourself unless you're used to doing somewhat difficult repairs yourself...one reason is because the airbag gas unit is in there too...so you have to be very very careful.

I would recommend that you find a good independent mechanic that knows this car...if lucky he'll let you order the fan yourself. I've bought one from Borton a few years ago and saved a bunch of $$.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon