The 'heating connection on the bulkhead' for the Citroën 2CV refers to the port where heating pipes run through the bulkhead. This part is crucial for the efficient functioning of the heating system, as it channels warm air into the car's interior. The bulkhead itself acts as a barrier between the engine compartment and the cabin, and the connections ensure that the heating pipes are securely and leak-proof attached, contributing to comfort and warmth during cold driving conditions. Proper installation and maintenance are key to optimal performance.