1991 Volkswagen Jetta • 4 cylinder 2WD Automatic • 2,000 miles

I have a Haynes auto repair book and I followed the instructions on the heat exchanger removal however it still appears attached somewhere and will not come out. I noticed two bolts with nuts on the engine firewall that were attached to the
fresh air box which did loosen things up a bit but the fresh air box still feels too tight and will not come out. The Haynes guide did not mention the bolts which leeds me to believe
their instructions are not complete. Thanks.
February 1, 2011.

I'm not exactly sure what all you've done so far. But the A/C system has an evaporator also located inside the same housing as the heater core, and in fact, they look the same.

According to "AllData", you must also remove the evaporator in order to get the housing out, before you're able to remove the heater core. To do that, you must evacuate the A/C system, remove the hose manifold at the fire wall then slip the housing out.

Did you also remove the defroster duct and instrument panel support bracket? After removing those, you can try slipping the housing out without evacuating the A/C system. Maybe you can wiggle the evaporator out of the housing while leaving it in place. But it'll be tight and tricky, besides it not being the proper procedure.

But sometimes there's more than one way to skin a cat.

Ernest Clark
Feb 1, 2011.
Attached is an exploded view of the heater housing and bolts location. Hope it is helpful.

Feb 1, 2011.