Blue is LOW; RED is high. You are wise to have double checked, though. Sometimes the previous work will be "different". The thick hose where you describe is the low side. Gauges help a lot when dealing with the A/C (borrow, beg, try Autozone tool loan program).
The Golden Rule
1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)