How can I import non-unicode text file by Feeds module?
I can only provide high-level guidance here, but you need to use the Feeds Tamper module, which allows you to alter data between when it is read from the source, and then passed to Feeds.

However, I don't think there is an existing tamper plugin that can handle your situation; you will have to create your own.

There are two patches in the issue queue that may provide guidance:


https://www.drupal.org/node/1817516
https://www.drupal.org/node/2263119 (disclosure, I wrote this one)


You can take one of those two patches, and update them to use your character set instead of the ones in the patch.

For example, in this patch, you would need to update

+function feeds_tamper_utf8_encode_callback($result, $item_key, $element_key, &amp;$field, $settings, $source) {
+  $field = drupal_convert_to_utf8($field, 'ISO-8859-1');
+}


to use your encoding name instead of 'ISO-8859-1'.