A/C BLOWING LUKEWARM TEMP AIR

2005 WORKHORSE STEP VAN
VIN #5B4KP42U753411418
6.0L V/8

The compressor locked up in this truck just before the engine went. I replaced the engine; on the A/C system I replaced the compressor, expansion valve, drier and evaporator core. I flushed all the a/c lines & the condensor and added the correct amount of oil to the compressor when I installed it. The comp. Clutch engages and the a/c system is working but am getting only 72-74 deg temp out of the vents. I've evacuated the system again, vacuumed it with no leaks and then recharged it. I need to know what's causing the high ven temps; below are some specifics;
AT IDLE)
1. Drier sight glass full of air
2. Low press reading 44-46
3. High press reading 295-305
4. Vent temp 72-74 deg @ low fan speed
AT 2,000 RPM
1. Drier sight glass mostly full of air
2. Low press 30-35
3. High press 360-380
4. 72-74 deg @ low fan speed