It will be fine to store good in the pantry. You are right to ask this question, how've not for the reason you think. Because of the air handler will require make-up or return air, it will need to be connected in some fashion to the rest of the house; usually this is through a return duct or an air intake in the AHU. If the latter is the case, make sure there is sufficient ventilation into the pantry to allow air to be returned. This might be achieved through a louvered door to the pantry or a register above it.

thank you Peter! I appreciate your feedback! there is a return duct in the ceiling. I just wanted to make sure that it would still be ok to put stuff in there. I don't want to mess it up.

Air handlers require regular maintenance. Filter(s) need to be changed every 3-4 months, and the coil, inside the air handler, may need replacement in 10 years or so. In other words, be sure that there is adequate room to service and repair the unit when the time comes.

VCFA - there are a lot of different options regarding filters. Return located filters vs handler located filters, 1 in vs 4 in etc etc.

In my neck of the woods, filters are typically on returns. An air handler in a pantry would not have enough air flow (typically) to act as a direct return - ie no return duct.

The fact is there are manufacturer's requirements for clearance and that should be addressed but this filter talk may be irrelevant depending on the installation.

"...this filter talk may be irrelevant depending on the installation..."

Or filter talk may be very relevant depending on the installation. Pretty much covers the bases, don't you think.

But I completely agree; there are all sorts of installations, so it's good for the OP to understand all the possibilities and then check out what applies to their specific situation.