Are you speaking of the Heater Core thats inside the dash? If not then ignore my post. If we're talking the same thing then heres my experience: I had to replace mine a year ago in my 94 SE. I don't know how much difference there may be between a 92 and 94 but I did find it to be most of a saturday. Mostley it was because it was my first time working behind this dash with often VERY little hand room to get at various little nuts or bolts and a Very confined space in the engine compartment to get at the hose clamps that come from the portion of the core that protude into the engine area.
First! Disable your radio security function THEN disconect the Neg terminal on the battery as you are trying to prevent the passenger airbag from going off. Even so be careful while in the dash area.
Second, disconect the control module from its harness(after first disconecting the Neg terminal from the battery) its underneath the passenger side of the dash, and unbolt it from the fire wall and remove it out of you way. At some point you will want to remove the inside of your glove box to gain some access to the mounting hardware that is inside the dash to unbolt a housing cover off of the core.I found that I was only able to unbolt a portion of the housing but it was enough able to then wedge the core out with just a little bit of effort.
Third, before the core will come out you'll need to remove the hose'* from the to tubes that protude into the engine comparment. Their below the fuse panel thats in the engine copartment on the passenger side, I fouund that removing the fuse cover gave a little more room. The clamps are NOT easy to get to. If you have the screw gear type all the better, if not and their the squeeze type clamp(horrors!) as mine were, the the best way I found without having any kind of specialty tool, was to use a medium to large sized pair of vicegrips and with a little trial and error was able to find the right opening to use on the vice grips, and then wedge one of the handles against the frame or firewall and press the other handles with my hand to close and lock the vicegrips on the clamp then the grips will hold the clamps open to where you can then slide them off of the hoses. I found my hoses to be stuck so bad that I had to cut them off and replace
them. Then you can get back under the dash ans remove the core.
I hope this helped.