88 C1500 LS Swap & AC Cabin Temp

[EVRLET]

We did a crate gen III LS 5.3 swap into the 88 using the Holley mid mount accessory drive that uses the Sanden SD7 compressor. All AC components in the engine bay are new and converted to r134. The only remaining factory AC parts are the HVAC box under the dash, evap and heater core. I inspected the evap core and vacuumed out the debris in the box. The drier and its tubes are cold to the touch, so I feel the evap core is not clogged and working just fine.


The blend door appears to be operating correctly and moves accordingly when changing temps on the dash hvac controller.


I charged the system with 32 ounces of 134, as most say that is the equivalent amount when converting from r12.


Truck uses a 3-row aluminum radiator with dual 16" spal fans and the pcm controlling the lo and hi speeds. Truck idles with low speed fans on and the coolant temp is around 180. The ambient temp during testing was around 95 degrees.


The cabin temp with AC blowing on high only gets to 75-76 degrees, verified with thermometer in vents. I had a shop fan in front of the truck with the grill removed, the e-fans on lo speed.


I raised the engine idle rpm to 1800, put the e-fans to hi, and the ac cabin temp went to 68-70. On hi speed, the spal fans are pushing/pulling 4,000 cfms, so it's plenty of air.




For you all who have LS swaps in your OBS, specifically the 88-94 years with the old dash, what is your AC cabin temps? 68-70 degrees sure seems "warm".

[Boog]

That could very well be the blend door in the evaporator case is not closing completely. You could pinch off the heater hose from the engine to fire wall and see if that helps bring the air temp inside down.
The blend door actuators aren't terribly expensive if needed.