[Wataru]

I asked this question on another forum, but want some other possible reasons...

When I accelerate quickly, say 0 - 80 with the A/C on Max or Norm, when I hit about 3000RPMs, the A/C will switch over to vent for about 5 seconds, then back to Norm or Max.

I was told it was a leak in a vacuum hose. Anything else possible? Basic stock A/C.

[PacificMustang01]

Interesting.....

By switch over to vent, do you mean the A/C kinda goes off and it just blows outside air, then A/C kicks back on?

If so then I am glad you posted b/c I have noticed the same thing (and when the defrost on too, since that uses A/C). Not only do I get this issue w/ my mustang, but also with 2 other Ford escorts I've had also. I've also noticed similar thing sometimes driving other brand rental cars. Not all makes have done it, and I don't remember ones that did.

I have always thought this was the computer sensing the need for more power and dis-engaging A/C load to gain it.

But never thought of possible leak in vac system? Since I've seen it w/ many different cars my guess is that it is normal. However, I too would love to hear if anyone else thinks otherwise......If it's something that needs a fix'n and simple as a vac hose I'm all for making it 100% right/working......

[Wataru]

Originally Posted by PacificMustang01 Interesting..... By switch over to vent, do you mean the A/C kinda goes off and it just blows outside air, then A/C kicks back on? If so then I am glad you posted b/c I have noticed the same thing (and when the defrost on too, since that uses A/C). Not only do I get this issue w/ my mustang, but also with 2 other Ford escorts I've had also. I've also noticed similar thing sometimes driving other brand rental cars. Not all makes have done it, and I don't remember ones that did. I have always thought this was the computer sensing the need for more power and dis-engaging A/C load to gain it. But never thought of possible leak in vac system? Since I've seen it w/ many different cars my guess is that it is normal. However, I too would love to hear if anyone else thinks otherwise......If it's something that needs a fix'n and simple as a vac hose I'm all for making it 100% right/working......

That's the first thing I thought of too. And it doesnt BOTHER me that much since it doesnt effect the fuction of the car.

Ive not put my hand over the vent to see if the air is from the outside or cold, like defrost. I shall go around 90 today and let you know

[PacificMustang01]

Nice. When mine does it I can tell the A/C compressor turns off, the air blowing out is warm and I can feel the compressor disengage.

[mooses]

The AC clutch is disengaged under WOT.

[PacificMustang01]

Kinda figured as much....is this controled by the computer, or some other sensor/relay somewhere. Just curious as to what give it the signal to do so under WOT?

[Codeman]

it is controlled by your tps sensor i believe, and this tells the computer to disengage the a/c clutch due to the demand for the power.

[v606er]

I always turn the radio, A/C, and anything else off before punching it. Get to hear her wind up better

[Wataru]

Originally Posted by mooses The AC clutch is disengaged under WOT.

+1 thank you for that bit of advice!

I got out on the highway around 12 noon and got it upto 85 and it did switch to vent for roughly 7 seconds and it was warm.























....it was good to go fast. I rarely get to open it up and I needed an excuse.

[RFM 40th V6]

It's a programed strategy. Just like when you're at idle and you turn on the a/c the idle bumps up.

When you go WOT the computer wants to make sure that you've got all the available power possible so releases the magnetic clutch to free up horsepower.

Nothing to worry about here. If it was switching from vent to defrost when you punched it I would suspect a vacuum motor.