Narrative:

I was flying as the first officer (first officer) off xxr in ZZZ. After liftoff I attempted to trim the nose up and there was no response from the electric trim. I notified the captain and we continued the departure and cleaned the aircraft up. I reverted to the manual trim wheel to adjust the trim. Due to the load on the airplane; the wheel was moderately difficult to turn. I was aware that I could unload the aircraft to make it easier but I did not feel the need to upset the passengers at that time. The captain tried his electric trim which also would not trim the nose up. However; the electric trim would trim nose down. We then leveled off at 11;000 ft.; [requested priority handling] and ran the trim inop checklist. As the flying pilot; I only flew the airplane and talked to ATC while the captain managed the [situation]. The checklist directed us to disconnect the trim system and fly a flaps 15 landing. We chose [priority] return at ZZZ and landed about 7;000 pounds overweight. We also called a deadheading check airman up to the cockpit as an extra set of eyes. I configured early so that I wouldn't need to trim much on final. The overweight flaps 15 landing was uneventful. ATC was very accommodating. I know I checked the trim system on the ground and it tested good. The captain had a habit of resting his knee against the trim wheel I and recall warning him to move it prior to the check. At the gate maintenance boarded and we showed them how it would trim nose down but not up. Upon further inspection we realized if we trimmed all the way nose down it would then trim nose up; but only for .5 seconds before stopping again.

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Original NASA ASRS Text

Title: B737 flight crew reported electric trim malfunction during climb.

Narrative: I was flying as the FO (First Officer) off XXR in ZZZ. After liftoff I attempted to trim the nose up and there was no response from the electric trim. I notified the Captain and we continued the departure and cleaned the aircraft up. I reverted to the manual trim wheel to adjust the trim. Due to the load on the airplane; the wheel was moderately difficult to turn. I was aware that I could unload the aircraft to make it easier but I did not feel the need to upset the passengers at that time. The Captain tried his electric trim which also would not trim the nose up. However; the electric trim would trim nose down. We then leveled off at 11;000 ft.; [requested priority handling] and ran the trim inop checklist. As the flying pilot; I only flew the airplane and talked to ATC while the Captain managed the [situation]. The checklist directed us to disconnect the trim system and fly a flaps 15 landing. We chose [priority] return at ZZZ and landed about 7;000 pounds overweight. We also called a deadheading check airman up to the cockpit as an extra set of eyes. I configured early so that I wouldn't need to trim much on final. The overweight flaps 15 landing was uneventful. ATC was very accommodating. I know I checked the trim system on the ground and it tested good. The Captain had a habit of resting his knee against the trim wheel I and recall warning him to move it prior to the check. At the gate maintenance boarded and we showed them how it would trim nose down but not up. Upon further inspection we realized if we trimmed all the way nose down it would then trim nose up; but only for .5 seconds before stopping again.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.