I have a 2-year old 3.5 ton Carrier (Mod# 38CKC042) residential condenser unit with a SEER 10 scroll compressor. Every summer, on really hot days the compressor tries - but fails - to start; until the late afternoon. The fan for the condenser unit runs fine - and every few minutes I hear the compressor try to start (for maybe 1 second) before kicking off. The vendor added a Total-Line "Smart-Start" (Mod# P290-0805), but the problem persists. What could be the cause?