gcdidthis

i have read through a few threads to answer my questions but have not gotten my head around a couple issues...

I have the automatic type a/c dash unit with max air etc.

1. i get cold air but only through defrost vents on Max Air.
on Automatic, i get full air flow through all the vents, but only cold, and it seems a LOT of airflow at 40 or so...

not being able to see a diagram on how the system works, and from what i have read, there is a difference in airflow because of the blend door.

is my problem easy to troubleshoot? or is there a series of issues.
like, do i need to just top up the coolant?
is there a vacuum issue keeping the door shut at lower rpm?

eff1fifty

I would guess a blend door acuator would be the cause.

Do all your fan settings work? Hi-med-low etc?
There is a blower motor resistor under the passenger side dash that wears out and can cause a little bit of funkiness.

gcdidthis

yes. all fan settings work. the air is actually cold, just no flow out vents on max. it comes out the same as on defrost. so thanks for narrowing it down...

eff1fifty

If you toggle defrost to max to floor etc. you can usually hear the blend door acuator move.

jstockert

The blend door only moves when the temp setting is adjusted. Another door in the center of dash behind the radio is the door that controls the air flow to defrost.

eff1fifty

Always choose door #3!

I stand corrected.

BruceBHT

Had same issue. Your vacuum hose is probably broken next to the battery going into firewall. P/U some hose at any auto store and replace or splice new line in. Should fix issue and somehow makes truck run better also.

NOTE !!! existing hose looks smaller than whats at the store, this doesn't matter, get the smallest you can find O'reilys has them.

jstockert

I would lean more toward a vacuum line off under the dash that hooks directly to ac control unit.
But I'm no expert, just learned knowledge from working on my truck.