If you are somewhat knowledgable about cars and working on them in could be done in 2-3 hours, but if you aren't so lucky is could take an entire day. you have to completely remove the dash and then take the ac lines and heater hoses off and then remove the big black box under the dash on the passenger side. then take all the screws out on the perimiter of the box. replace the heater core and reassemble. then you'll have to vaccum and recharge the freon for your ac