the air blows out of the vents cold but it is the same volume of air at any fan speed..... you can hear the blower motor change speeds and it sounds like the air is dead heading somewhere like a flapper isn't opning correctly. it will change back and forth between defrost. floor and the dash... but it won't blow out the vents hard enough to blow out a match.....HELP!

will be back on here in an hour or so. i'm going to geta chilton or haynes manual and se what i can figure out. if anyone has had this happen please let me know what you had to do to fix it.

thanks in advance

Benjamin

99 chevy 4 door 3500 drw

 

I would say you have a vacuum problem.

 

Well I have no help for ya but I really can't say I feel for ya either I used my heat today Hope some one has an idea for ya

 

where would the vacuum input to the cab be comin from and in to the cab on this chevy?

 

It should be coming off the intake manifold and through the firewall. Its a small black shiny hard tubing.

Does your truck have cruise control? and does it work?

 

yes and yes

not my truck, it is a co-workers and i'm not impressed right now with his Real Truck as he calls it.....

there is from what i can see no vacuum lines going into the firewall. there is one that looks like it goes somewhere on the passenger side, it goes right under the turbo power cover and looks to be paired to an orange tube. but the black one id plugged off and looks almost like it is factory done that way.

 

any body? we are ~350 miles into a 1400 mile trip and the A/C would definately be nice to have .......

 

There aren't any vacuum lines on these. Does it only blow weak out of the vents or out of the other positions?

If it's weak in the other places it's quite possibly a plugged evap core.

The mode door actuator is located on the driver's side of the heater case. Look around to the right and above the go pedal and you should see it. There are 1 or 2 little links that run from the actuator up to the door. I would bet that one or both of these have fallen off or broke.

You should also watch the motor run. There is a silver **** with a notch in it that pokes through the actuator housing that you can see. IIRC there should be about a 90* change in the notch position if the actuator is making a full swing.

 

As JC Said If You Have Had It On For A Long Period Of Time & The Airflow Is Consistently Crappy Out Of All The Vent's Defrost & Floor - I'd Say Your Plugged or Frozen.

 

update and i hope it is fixed.

after letting it sit over night we left out this morning and it about froze our tails off it was working so good. worked for about 3 hours before it started blowing weak again. we made a few stops for work and it seemed to do ok but later on today we stopped at the hotel and i was looking to see if i could see anything out of the ordinary, as there was alot of water coming out of the box under the hood where the condensation drain is. then it hit me it might be low on refrigerant and be getting too cold and freezing up and blocking the evap core and making a restriction (we have very high humidity right now)

i was gonna go to walmart and get a can of stuff with a gauge so i could get a low side reading but the owner of the truck wanted to let a professional do it. before we took it to them i took the high side cap off the line and coolant was steadily leaking out of the schrader valve slowly. we found the leak. took it to the shop, they said the low pressure switch was bad causing it to run when it got too low and freeze up, it was low on refrigerant, and the orfice tube was stopped up creating a blockage. changed all that out, re-charged it and hopefully we will be good to go


thanks for all the advice guys.