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tmumolo

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Discussion starter · #1 ·
Does anyone know if the AC on the MK3 has a shut off mechanism on hard acceleration? I live in an area where there are some two lane highways; when it's necessary to pass a slower vehicle or truck I almost always hit the AC button to turn off the air before I pass; idea being to get the most power to the drive wheels by turning off the AC compressor. Maybe it's confirmation bias but it does seem to make a difference. Is it my imagination?
I was just wondering if the cars computer has a built in way of doing this automatically.
Any thoughts?.
 
#2 ·
The car does have the ability to disengage the AC, and alternator I believe, when the pedal is at WOT. I'm not sure if it's using an electromagnetic clutch or something else, my google-fu is weak this morning.
 
#3 ·
tmumolo said:
Does anyone know if the AC on the MK3 has a shut off mechanism on hard acceleration? I live in an area where there are some two lane highways; when it's necessary to pass a slower vehicle or truck I almost always hit the AC button to turn off the air before I pass; idea being to get the most power to the drive wheels by turning off the AC compressor. Maybe it's confirmation bias but it does seem to make a difference. Is it my imagination?
I was just wondering if the cars computer has a built in way of doing this automatically.
Any thoughts?.
Click to expand...
I believe all vehicles have a WOT AC compressor clutch disengage.
 
#5 ·
A/C Request

The HVAC control module uses a dedicated wire to send the A/C request message to the BCM. The BCM sends the A/C request through the High Speed Controller Area Network (HS-CAN) to the PCM .

When an A/C request is received by the PCM, the PCM engages the A/C clutch relay when:
• the refrigerant pressure isn't excessively high or low.
• the engine coolant temperature isn't excessively high.
• the ambient air temperature is above 6 C (43 F).
• a WOT condition is not present.
• the evaporator discharge air temperature is above 7 C (45 F).

I assume these bullet points are "and" conditions meaning all must be true for the AC clutch relay to be energized, thus allowing current to the AC clutch coil.
 
Discussion starter · #11 ·
danbfree said:
Look out, "pretty much" isn't good enough for this guy who won't just Google it! LOL!
Click to expand...
Don't make assumptions I Google'd it and didn't get a satisfactory answer; I thought this forum was for sharing information. And your correct " pretty much" is never good enough, and shouldn't be, when you want a definitive answer.
Thanks to those who responded with information based on knowledge.
 
#13 ·
danbfree said:
Look out, "pretty much" isn't good enough for this guy who won't just Google it! LOL!
Click to expand...
The OP's question was already answered correctly.

My point was that virtually all modern cars built within the last several years have WOT A/C cutout as the A/C compressor is controlled directly by the PCM.

There is absolutely no reason as to why a Ford Focus would be the exception to this rule.
 
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