A/C power usage

[Sludgy]

I used the Scangage to determine the HP used by the A/C. With the A/C off, the Scangage read 0.4 gph. With it on, the Scangage oscillated between 0.5 and 0.6. Call it 0.6.

So assuming 20% efficiency for the diesel at idle:

Fuel rate at idle, A/C off
0.4gphFuel rate at idle, A/C on0.6gphA/C fuel usage0.2gph23000BTU/hrFuel conversion efficiency20%Combustion energy to HP4600BTU/hrEnergy conversion factor2545BTU/hr/hpMechanical HP1.8



This is at idle. I don't know if it varies much with RPM.