A/C goes to defroster vents on acceleration
Asked by Scott Aug 17, 2017 at 05:59 PM about the 2004 Ford Explorer Eddie Bauer V8 4WD
Question type: Maintenance & Repair
I have a 2004 ford explorer v8 4wd eddie bauer 4x4. When I go uphill or
accelerate the A/C stops blowing through the vents. When I go downhill or
decelerate the air returns to the vents. Very consistent, no matter what mode
I set the air to (heater, vent, etc,). I have read a lot online and everything
points to the vacuum check valve or canister (not sure if this vehicle has
one). I need to know if the the problem is likely the check valve or canister
and where these are located so I can test/inspect and part numbers.
8 Answers
Check the vacuum lines where they attach to the vacuum tank.
Tom or F_O_R, thanks. Can you point me to where the canister is under the dash? Do you have access to any diagrams?
I believe they also default to "heat" for safety concerns for those who live in very cold climates who may get stuck on ice covered roads and not able to travel. If you see it begins blowing hot, it's normal.
I am not sure about the vacuum tank location on your car but on my Fords the tank is behind the battery box. It may appear to be part of the box itself.
F_O_R, I checked behind the battery box and everywhere in the engine compartment - no joy. Any chance it's under the dash? I think I have seen references to that elsewhere. Thanks.
Others I have seen in other explorer sport trac 4.0 V6 are round black plastic about the size of a baseball. I have also seen them in various locations. Try following the very small black plastic vacuum line coming from the engine. There may be a check valve somewhere along the line. It should terminate at the vacuum reservoir. You should check to make sure there is no leaks in the line as they are plastic and tend to crack from engine heat after years of use. If you use a small hand operated vacuum gauge, you can disconnect the line and check the vacuum. If a cracked line is the problem, replace with rubber hose of same inside diameter and it will last longer. Also, if the canister is located somewhere not accessible you can purchase another canister, abandon the original one, and mount it where it is more accessible, especially if it is located somewhere like inside an evap housing.
Scott, Did you ever find the issue with this? My 04 Explorer just started having the same issue.
So I have a 2006 Mercury mountaineer on my coolant line to the heater core I have a valve with a vacuum line I replaced that valve $22 and it fixed my problem I have v6 4.0L
