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HVAC somehow blocked, it stops blowing air. blower works fine. help!!

I

Iron_Lamb

New Member
Joined
Oct 6, 2012
Messages
8
Hello Everyone.  Ive Been Researching This problem For Months Now.  My Heater Or Ac Will StopAir Flow And Freeze Us Out.  It Gets Loudbas If The Air Flow Is Hitting A Closed Door.  BlowerWorks Fine.  The Modes Still Work As U Can Feel A Trickle Of Heat On High Change To Dash And Back.  Temp Still Goes From Hot To ColD and back.  I Dont Know What Door Would B Sticking.  It Only Resets After Sitting All Night.  Most Of The Time. It Does This Lock Up Adter About 15 To 20 Min Of Driving.  Just About When Cab Is Warm.  Im Dumfounded.

2004 Chevy Ava 4X4.  Dual Auto Climate Controls
 
Blend doors
 
I Had The Blend Door Unplugged,  The One Below Center Console.  And The Scenario Still Happens.  Like I Said,  I Can Change The Temp and it works,  the motor actuator works because they can go from dash the floor just fine.  I can't figure out what door would be shutting and causing the air blockage
 
hi.  I was wondering if anyone could help direct me to which actuator to replace.
 
I replaced the blend door actuator and the problem persists.  its not the mode actuator either as it still changes positions.  so where else is there a door that could block airflow completely?  I can't figure it out for the life of me.  or why there would be a door that could be in a position to completely block the flow of air.  can anyone help? 
 
ok.  I'm going to do one last outcry for help.  my heater/ac will stop producing airflow after 15 to 20 min of driving depending on the temperature.  the blower roars loudly and it soulds like airflow is completely obstructed.  all of the positions work and i even replaced the blend door actuator because everyone always says its blend doors when theres any hvac problem whatsoever.  the temperature works fine.  I can feel a trickle at full blast and this trickle will change through all the modes and temperatures.  shutting the truck off and getting back in it doesn't fix it either.  it seems it has to sit all night to fix.  and sometimes might take a day or two.  somewhere there is a door completely blocking all airflow.  where would this occur?  I can't seem to figure it out.

thanks again.
 
It sounds to me like your blower motor resistor is going bad... it is located under the glove compartment behind the plastic that covers the vents

see if this helps you out to see if you can pull it and visually inspect it  (y)

http://www.chevyavalancheclub.com/index.php?topic=4565.0
 
wyotonka said:
It sounds to me like your blower motor resistor is going bad... it is located under the glove compartment behind the plastic that covers the vents

see if this helps you out to see if you can pull it and visually inspect it  (y)

http://www.chevyavalancheclub.com/index.php?topic=4565.0
Click to expand...

all of my fan speeds work fine.  the air is just blocked.  turned up all the way, the fan is loud as hell and even louder if you switch it to cabin air.  but still the airflow is blocked.  I was freezing to death on my hour drive to work.  I read somewhere about the evaporator freezing up and blocking air.  is that a possibility in the avalanche?  I can't visualize how the different pieces are places in respects to air flow. (looking at the blow apart diagram for ordering oem parts.)
 
Reduced Air Movement

    Reduced airflow is when the blower motor is trying to move air through the vents but the resistor isn't sending enough power to move the air with much pressure. The blower motor resistor is receiving power but not the full force. Reduced air movement can occur at all of the different speed settings of the motor blower. Depending on how much resistor is still functioning, the reduced airflow could be an intermittent problem.


Read more: http://www.ehow.com/list_7496749_signs-bad-blower-motor-resistor.html#ixzz2wMBU53sy

it would be worth looking at for what little effort it takes to get to it IMO

and judging by how long this has been a problem I would say that if it is the resistor the motor is probably not far behind
 
I will pull the resistor and check it tomorrow.  but the way the fan blows with such force makes me think it's getting enough power.  just the airflow is blocked.  it sounds louder than usual and sounds blocked toward the passenger side.  I found this image
hvac-air-flow.jpg


I read somewhere on these forums about the evaporator freezing.  my condensor(on the other side)  is always frozen,  as in covered with frost and ice.  I think my ac system over compresses. maybe the low pressure switch.  in any event,  if that side freezes up,  maybe the other side,  the evaporator freezes also.  I have no idea how to fix this.  besides flushing ac system and replacing that low pressure switch.  I can't think of how else there would be a blockage.  I should mention this has happened in the summer also.  and in the summer, on full blast,  my ac blows white mist sometimes.

thank you guys so much for your help
 
okay so I think I finally found the source of my problem.  I was convinced my evaporator was freezing solid blocking the air flow.  because my hoses were always frosted over at the accumulator.  I replace the low pressure switch and I thought that would do it but it seem to still do the same problem.  after even more research I decided to check the relay.  I want to remove the relay, and it came out quite easily as someone had clipped of alL But One Contact,  and used a jumper wire to make sure the compressor was always running.  I had replace the AC compressor last year in the one that I removed had the clutch melted to the compressor pulley.  someone must have just done a quick fix to make sure it never cycle ofF.  Or someother Reason.  anyway I plan to replace the relay tomorrow and then I will let you know if this permanently fixed my problem
 
No 03s had them only 02s
 
:eek: As Rosana Rosana Dana used to say........Never mind........... :E:

For all you youngsters out there, she was on the original Saturday Night Live.....Back when it was actually funny.... (y)
 
raiderron said:
... the original Saturday Night Live.....Back when it was actually funny.... (y)
Click to expand...

That's what I tell people too!  >:D
 
Iron_Lamb said:
okay so I think I finally found the source of my problem. I was convinced my evaporator was freezing solid blocking the air flow. because my hoses were always frosted over at the accumulator. I replace the low pressure switch and I thought that would do it but it seem to still do the same problem. after even more research I decided to check the relay. I want to remove the relay, and it came out quite easily as someone had clipped of alL But One Contact, and used a jumper wire to make sure the compressor was always running. I had replace the AC compressor last year in the one that I removed had the clutch melted to the compressor pulley. someone must have just done a quick fix to make sure it never cycle ofF. Or someother Reason. anyway I plan to replace the relay tomorrow and then I will let you know if this permanently fixed my problem
Click to expand...
Hey - got a 2007 Ava

I’ve been having the same issue with the AC. It runs fine then freezes up and all the actuator doors seem to close so limited to no airflow and then turn off AC and it warms up and actuator opens and works fine for 20 minutes or so and then the cycle continues.

AC compressor freezes up. Replaced low pressure switch and recharged system still an issue.

Did you figure this one out? Was it the relay?

Thanks
 
If freezes then:
low on refrigerant
Not enough Air flow across Evap Coil or evap coil nasty clogged.
 
Refrigerant is good, low pressure switch replaced and system recharged - relays checked - sensor above driver replaced- I read there might be a temp sensor next to the evaporator that goes bad requiring the dash to be taken out to be replaced.

I cleaned the outside of the evaporator. If clogged internally, how do you purge it?
 
when you say freezes up - you actually see ice on compressor lp line as well as evap inside ducts????

Scan for any AC codes?
seems you have some sort of issue and need to read codes before throwin parts at it.

and better describe your issue...
 
ygmn said:
when you say freezes up - you actually see ice on compressor lp line as well as evap inside ducts????

Scan for any AC codes?
seems you have some sort of issue and need to read codes before throwin parts at it.

and better describe your issue...
Click to expand...
Both the evaporator inside the car and the accumulator outside freeze up. No codes showing on my scan tool. Most of the air flow is blocked once the evaporator freezes. Turn off AC button and in 5 minutes it thaws and then turn it back on and it works fine for 15 minutes or so and then refreezes.

So compressor not being told to shut off. Went to the dealer and looked a schematics and there does Not l appear to be an evaporator temp sensor on the evaporator like there is on Silverados. There are two sensors in the duct that I think could be malfunctioning or some other issue with the control module.

Probably going to try the dealer again but you have to drive it for 30 minutes or so to recreate it and they couldn’t replicate it several years ago.

Any ideas?
 
It’s not the actuator doors it’s the evaporator freezing that prevents the air flow. Compressor is not shutting off so thinking it’s an air duct sensor not working.
 
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