A B737-300'S LEFT LNDG GEAR INDICATED UNSAFE WHEN RETRACTED. THE LNDG GEAR ALL INDICATED SAFE WHEN EXTENDED. THE FLT RETURNED FOR A NORMAL LNDG.

Narrative

UPON GEAR RETRACTION AFTER TKOF THE L MAIN GEAR RED LIGHT REMAINED ILLUMINATED WITH THE GEAR HANDLE BOTH IN THE UP AND OFF POS. THE AFTER TKOF CHKLIST WAS ACCOMPLISHED AND I HAD THE FO MAINTAIN 210 KTS IN THE CLB. THERE IS NO IRREGULAR PROC FOR THIS PROB; SO I ELECTED TO TRY CYCLING THE LNDG GEAR. THE GEAR INDICATED DOWN AND LOCKED WITH 3 GREEN LIGHTS AND NO RED LIGHTS. UPON RETRACTION; THE SAME L MAIN GEAR RED LIGHT REMAINED ILLUMINATED. I ASKED ATC FOR A LEVELOFF AT 13000 FT AND WE REMAINED AT 210 KTS IN ORDER TO STAY CLOSE TO THE AREA WHILE I COORDINATED WITH DISPATCH AND MAINT. MAINT WAS UNABLE TO HELP US RESOLVE THE ISSUE AND AFTER CONSULTING WITH DISPATCH AND MY FO; THE DECISION WAS MADE TO RETURN TO ZZZ. ATC ASKED IF I WAS DECLARING AN EMER; AND SINCE THE GEAR INDICATED NORMALLY ON EXTENSION; I DID NOT DECLARE AN EMER. DURING THE RETURN TO ZZZ; APCH REQUESTED OUR FUEL REMAINING AND SOULS ON BOARD; WHICH WAS A REQUEST FROM TWR. I BELIEVE TWR DECLARED AN EMER FOR THIS FLT. UPON GEAR EXTENSION ON THE APCH TO RWY; THE LNDG GEAR INDICATED DOWN AND LOCKED WITH 3 GREEN LIGHTS. THE FLT LANDED NORMALLY AT ZZZ WITH FIRE EQUIP STANDING BY AS REQUESTED BY ATC. WE TAXIED NORMALLY TO THE GATE WHERE THE AIRPLANE WAS TAKEN OTS.