Air Conditioner goes to Deforst when you accelaerate Fan dont change just air flow WHY????? We Replaced the plentum thats when it started doing this problem
Country: United StatesMake: BuickModel: Le SabreYear: 1998Engine: 3.8
Hello and good evening. Look for the vacuum line that comes from the firewall for the air conditioning. That vacuum line is either cracked or the vacuum line that goes to the vacuum reserve canister has become disconnected. When you accelerate, vacuum diminishes normally, that vacuum canister stores a reserve of vacuum to maintain vacuum during those times. You most likely disturbed one of the vacuum lines replacing the plenum. The lines from the air conditioning is usually a small black hard plastic line and the one going to the vacuum canister is most likely rubber. Let me know if you need anything as you proceed through this.
Your JA Expert,
Ok We did what you said. We replaced three loose rubber connectores and made sure there were no vac leaks . Still does the same thing. We are wondering about these relayes. There is a vac hose comming out of the throutel body it runs to a relay it goes into the rely and then out to storage cannister it is under the conyrol mod. There is a 1/2 inch hose that is connected to a relay and then the cannister but stops there . There is then a line going out of cannisted to fire wall for clinit control. So where would you start.
Let me see if I can find some illustrations to help you. It has to be vacuum related. I will get them to you as soon as I can. We will fix this together, don't worry.
Ok, I'm going to start with these 2 diagrams. The first shows the vacuum feed to the HVAC system. This line will come right off the upper intake manifold and go into the firewall as a black hard small plastic line. Look for that item and make sure the line is not damaged anywhere. The second picture is the location of the vacuum reservoir. This is located under the vehicle. The instructions tell you to turn the front wheels to the right. It will be mounted forward of one of the front wheels. This is what is responsible for keeping vacuum under low vacuum conditions. With the car running, unplug the vacuum line to it and see if you have good strong vacuum at it. If you do not, you need to look for where this line became cracked or disconnected from the intake manifold. That will be the reason. Come back to me if you have any questions. You should have full manifold vacuum at that vacuum tank. I'm having trouble uploading the pictures. Look for my next post for the 2 pictures. I'm sending them right now.Ivan41090.9975285069
ASE Master Tech w/ 20+ years in the field. Self employed for 9 years. Member of AUTOLAB radio show.