Check for vacuum leak--either under dash or in engine compartment Check for bad vacuum motors under dash Defrost is the default position for this system There is a vacuum resovoir located behind your battery , it is for this condition.
When you accel your engine doesn't produce vacuum due to the throttle plate being open so a resovoir is there to hold a vacuum reserve so that when there is low vacuum produced by the engine there will be reserve to hold the vacuum motor applied preventing the air from changing direction in your dash.
When there is no vacuum the direction is at the defrost vents if you have a broken hose or no vacuum your ac would blow out the defrost all the time
But since it happens when you accel it sounds like your vacuum resovoir is cracked thus not allowing it to hold a vacuum
There are two possible solutions. ffirst is the door may be locked open where the exchange takes place for the direction of flow. Second is the vaccumm valve that operates the door. It is usually located under dashbut you can check vaccum canister to make sure there is enough vaccum.
Easy job on the 2002. Turn the two center air vents down and look inside above them. You will see a screw in each. Remove the screws and the face plate will come off. The radio is then bolted into the dash and can easily be removes. I hope no car radio theives are reading this!
wiring 2002 escalade radio
Yes. September 4, 2002
provide wiring diagram for Avalon 2002
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Check under the hood for a disconnected or damaged vacuum line. The controls are vacuum operated and if the vacuum supply is cut off the system defaults to defroster only.
Hi, It is not the blend door, that is for heat/cold changes. The mode door could be the problem, or stuck defrost door.
Your most likely issue is a bad hvac control switch. On older cars, this was operated by vacumm pressure, but on a 2002, it is all electrical. It may be that you need to replace the whole control unit.
Check for a broken vacuum line. The vacuum line controlling the doors on the heater/AC blower is a small hard plastic line. When it breaks it has little affect on the engine performance but the vents default to defrost for safety reasons. The few I replaced start at the front portion of TBI base. Your parts person can show you where it is and it isn't expensive.
when it happened to mine, it was because the arm behind the dash that controls the internal vent doors slipped off
Could be,a stuck open thermostat,low on coolant,plugged heater core,faulty temp blend door actuator,
Sounds like you have a vacuum leak - -bad or loose hose or defective diaphragm in one of the vacuum motors
Any of the following can cause this......... 1. Bad a/c - heater controller.. 2. Bad a/c - heater controller inside door operation.. 3. Bad, broken or cracked vacuum line/lines..
The 2002 Ford Expedition has 16 valves.
The 2002 Ford Expedition has a V8 engine.
you have a vaccumm leak defrost is the normal at rest vent setting