Does A/C actually affect engine performance?

Artsifrtsi said:
The standard fan is barely noticeable... The AUX fan however... Had it kick on for the first time in Moab, thought the truck was rigging for hover mode! Lots of noise, and billowing dust!
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mine have been rentals and I didn't pay attention to which fan it was, but I can believe that. I mostly noticed it on the trail or in traffic. And I've also heard it on other rigs when encountering them on the trail. It's quite distinct since it's variable speed so you hear it slowly ramping up and down.
 
I was under the impression that the PCM turns off the ac compressor during high load situations such as merging on the freeway or going up a hill
 
most modern a/c compressors are a lot more efficient than the older ones from days gone by. i once had a 1976 datsun 280Z and it was very noticeable when the a/c compressor would kick on. i only know my jeeps a/c is cycling when i hear the compressor clutch engage.
 
txbemis69 said:
most modern a/c compressors are a lot more efficient than the older ones from days gone by. i once had a 1976 datsun 280Z and it was very noticeable when the a/c compressor would kick on. i only know my jeeps a/c is cycling when i hear the compressor clutch engage.
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Your 280 had AC?!

It's been long enough that I don't even remember whether it was factory AC that didn't work or never had it at all. It was already a 25 year old vehicle when I bought it.
 
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freedom_in_4low said:
Your 280 had AC?!

It's been long enough that I don't even remember whether it was factory AC that didn't work or never had it at all. It was already a 25 year old vehicle when I bought it.
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it appeared to be a dealer add on. it had a knob at the bottom of the driver’s side dash at the console that had 0-10 on it. you could turn knob to 4 and it would blow a frosty fog out of the center a/c vents. would blow fog into the rear hatch area. coldest a/c i’ve ever seen in a vehicle. compressor would really lug the engine when turned on. recently had a 99 toyota camry that would blow the same frosty fog but, nothing like that ole Z car.
 
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I think Myth Busters covered the topic of A/C and MPG and showed that below 45 mph, A/C off and windows down was better for MPG, above 45 windows up and A/C on.


They did not test that theory in our house, in the summer time its 115-120.
 
My trans temp gets hotter when running the a/c, especially if sitting in traffic or going up a long grade (4.0L auto). It gets hotter under those conditions without the a/c, but I definitely notice an incremental increase with the a/c on.
 
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