A/C help please

[MarauderMatt200]

ok my AC doing something odd. When im getting up the freeway (not flooring it just normal driving) the AC will switch from blowing air regular out the normal vents to the dash vents and floor vents, When i let off the gas it will switch back to blowing normal. It only does this when im giving it gas for an extended period of time like getting onto the freeway or if i have it on cruise control and going up hill AC will start blowing the defrost vents and floor. What is this???

[Ambitious1]

You may want to reach out to Fastblackmerc, he is the authority on the EATC and air conditioning issues. He helped me out a couple of times. Great guy:

http://www.mercurymarauder.net/forums/showthread.php?t=99619

[BAD MERC]

Common problem, easy fix.

[RF Overlord]

Read this thread (http://www.mercurymarauder.net/forums/showthread.php?t=36922).

[MarauderMatt200]

thanks fellas ill contact FastblackMerc...i have bought my BCM from him awhile ago to fix that other common issue

[MarauderMatt200]

my main question is why only under acceleration does it do this? does that cause a vaccum leak?

[Mr. Man]

Sounds like the rubber washers in the EATC have cracked. Replace them with silicone washers and it should fix the problem. I believe they are 7mm washers.

[fastblackmerc]

my main question is why only under acceleration does it do this? does that cause a vaccum leak?

Not a vacuum leak but there is less vacuum under acceleration.

Sound like you need your EATC repaired. I can do it for you. PM me.

[RF Overlord]

my main question is why only under acceleration does it do this? does that cause a vaccum leak?Well, in actuality there already IS a vacuum leak in the EATC caused by the faulty o-rings, although this leak is very small. When the engine is under light load, there is high manifold vacuum...like 21 inches at idle. As you open the throttle plate, vacuum decreases until you are at 0 inches at WOT. Somewhere in the middle, depending on how bad your o-rings are, there is not enough vacuum to hold the HVAC actuators in the vent position, as they are designed to default to defrost on loss of vacuum, as a safety precaution in winter.

[Mr. Man]

Well, in actuality there already IS a vacuum leak in the EATC caused by the faulty o-rings, although this leak is very small. When the engine is under light load, there is high manifold vacuum...like 21 inches at idle. As you open the throttle plate, vacuum decreases until you are at 0 inches at WOT. Somewhere in the middle, depending on how bad your o-rings are, there is not enough vacuum to hold the HVAC actuators in the vent position, as they are designed to default to defrost on loss of vacuum, as a safety precaution in winter.
Straight up easy to understand explanation Baub. :2thumbs:

[Turbov6Bryan]

They are 007 orings. $3.50 for 100
http://www.oringsandmore.com/silicone-o-rings-size-007-price-for-100-pcs/

[MarauderMatt200]

Well, in actuality there already IS a vacuum leak in the EATC caused by the faulty o-rings, although this leak is very small. When the engine is under light load, there is high manifold vacuum...like 21 inches at idle. As you open the throttle plate, vacuum decreases until you are at 0 inches at WOT. Somewhere in the middle, depending on how bad your o-rings are, there is not enough vacuum to hold the HVAC actuators in the vent position, as they are designed to default to defrost on loss of vacuum, as a safety precaution in winter.

damn nice and easy explanation to understand, thanks

[fastblackmerc]

OP - I responded to your PM.