Abstract: A method for minimizing the clogging of a cooling zone heat exchanger of a reflow solder apparatus that includes the steps of: removing a gas/flux mixture from an exhaust zone (20) that is located adjacent a heated zone and/or a cooling zone; conducting the gas/flux mixture to and through a first filter chamber (22), conducting the filtered gas from the filter chamber (22) through a low pressure portion of a blower housing of a cooling zone (16), then subsequently to and through a high pressure portion (44) of the cooling zone that includes a collection tray (38), a mesh filter (48), a heat exchanger (46) and at least one perforated plate (50). The heat exchanger is thermostatically controlled at a preset tempering temperature that minimizes the collection of flux on its exterior surfaces while allowing a solder joint of an article to solidify.