My A/C works but the air doesn't blow out of the right vents. What's wrong?
A: The problem lies in
the controls that regulate the air distribution. The refrigerant circuit
only provides the means to remove the heat from the air entering your
vehicle. The control system handles the air distribution so that you can
select defrost, floor or dash vents.
In many cases, the air distribution
controls operate with manifold vacuum. That is vacuum created by your
car's engine. Your A/C system uses a canister or reservoir to 'store' vacuum
and operate 'blend' and air distribution doors.
In a lot of cases, when a vacuum
line under the hood is broken or left off (sometimes during other automotive
services), you loose the ability to control the air distribution. The typical
failure is that all the air is coming out of the defroster or the floor.
Those are usually the 'defaults' for the system. In order to correct the
problem, you simply have to find and repair the vacuum leak.
Although that sounds easy, there
are a lot of different vacuum lines under the hood of any vehicle. They are
typically small (about 1/4" diameter or less) hoses that are routed from
the engine. These can get loose, cracked or even sustain holes from hot exhaust
manifolds. Additionally, the actual vacuum reservoir can leak. That reservoir
can be located anywhere under the hood, but typically on the passenger side
close to the firewall. Check the hose connections and the canister itself.
Leaking canisters have to be replaced, but they are usually not an expensive