Does a partial achilles tear mend?

Possibly: Partial achilles tears can occur from trauma or degeneration. Some of these years can heal with nonoperative management. If there's continued pain or weakness, surgical intervention may be recommended.

Yes, usually: If the blood supply is good to the area and if pressure is taken off the achilles tendon, it will usually heal. However, it takes a long time for tendons to mend and they always mend with scar tissue. Some people heal unremarkably and others always have some swelling and tenderness, depending on how well the tendon heals. If tear is large, surgery may be required to repair.