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Anonymous Posted on Jun 18, 2014

A/c blows out defrost vents only - 1999 Chevrolet Express

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Marcos Lopes

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  • Chevrolet Expert 259 Answers
  • Posted on Apr 23, 2015
Marcos Lopes
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Joined: Oct 29, 2011
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You need to have a a/c mechanic look at it. to make sure the a/c system works

5 Related Answers

Michael Gutwein

  • 104 Answers
  • Posted on Feb 22, 2009

SOURCE: astro van 1997

There is a flap in your heater box that is controled by your vent switch by your heater controls. listen for a vacuum leak. that is common and hopfully the problem. there is vacuum lines that control the vent door that redirects the air to your vents.

Has your dash been messed with recently? if so i would check there first. you should hear a hissing if thats the problem.

Otherwise these also are common for that door flap to break and not switch NE more. thats the only 2 things that i can think of off th wtop of my head to be the problem. this would require the whole dash to come apart if its this problem

Michael
ASE certified

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Anonymous

  • 20 Answers
  • Posted on Feb 23, 2009

SOURCE: Heat wont blow through heater or defroster vents

common problem, check under dash by the gas pedal if control arms are muving went selecting from ac to heat cuz this it is the control for the vents to go from ac to heat and to defrost.

Anonymous

  • 432 Answers
  • Posted on Oct 06, 2009

SOURCE: All Air Conditioning blows our the defrost vents

Some thing you could look at would be this. The control is usually fed by a vacuum line or small hose thats is connected to your intake manifold.
With a cold engine,look for a skinny vacuum hose that runs from the intake toward the fire wall . It should be going inside the cab and connecting to the A/C vent control.Some times the hose becomes disconnected or splits or cracks due to heat under the hood.
Thats usually the trouble.
I hope this helps you.

airjer995

Jeremy W.

  • 5332 Answers
  • Posted on Sep 26, 2010

SOURCE: 2004 Silverado 2500HD a/c is

Sounds like it is going through the recalibration process. We run into this issue when replacing the batteries on these. In the underhood fuse block there is a HVAC fuse. Pull it, wait 30 seconds, put it back in, and turn the key to the run position. You should hear the vents moving around. wait for about a minute or so, do not touch anything. If the self test/calibration passes everything will return to normal. If after several attempts you can not get it to return to normal than there is a problem with the HVAC system that will need to be resolved.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Anonymous

  • 3 Answers
  • Posted on Dec 07, 2011

SOURCE: Heat wont blow through heater or defroster vents

Had the same problem. believe it or not i changed the gas cap and got heat all around. something about pressure.

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Airconditioner only blows out of defrost

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My heater does not blow in floor in a dodgeram 1500

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As per your problem mentioned. There are few solved help links to troubleshoot these problems. Go through the list and Click the link below:----

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These will help.

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No heat from vents

As per your problem mentioned. There are few solved help links to troubleshoot these problems. Go through the list and Click the link below:----

2000 Toyota Avalon: No heat on Passenger Side?

http://whatisbyme.blogspot.in/2012/05/2000-toyota-avalon-no-heat-on-passenger.html

------------

No heat on Oldsmobile Silhouette?


http://technoanswers.blogspot.in/2012/02/no-heat-on-oldsmobile-silhouette.html

------------

Heater blows cold?

http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html

-----------

Heat blows cold on drivers side and hot on passenger side?

http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html

----------

Hot air on the driver's side vents only?

http://repairhelpcenter.blogspot.com/2012/01/hot-air-on-drivers-side-vents-only.html

--------------

Temperature gauge does not move and no heat when heater is ON?

http://technoanswers.blogspot.com/2012/01/temperature-gauge-does-not-move-and-no.html

-----------

1992 Toyota Camry: A/C Control light Flashing and A/C not Blowing Cold?

http://technoanswers.blogspot.in/2012/04/1992-toyota-camry-ac-control-light.html

--------------


No heat, blower blows only cold?

http://technoanswers.blogspot.in/2012/02/no-heatblower-blows-only-cold.html
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Ford F150 Ac only blows through defrost vents?

http://technoanswers.blogspot.com/2012/01/forf-f150-ac-only-blows-through-defrost.html

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Dodge A/C come out of defrost vents only?

http://technoanswers.blogspot.com/2012/01/dodge-ac-come-out-of-defrost-vents-only.html

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Ac vacuum line on dodge cummins?

http://technoanswers.blogspot.com/2012/01/ac-vacuum-line-on-dodge-cummins.html

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Ford ranger AC blows cold through defrost vents instead on cabin vents?

http://technoanswers.blogspot.com/2012/01/ford-ranger-ac-blows-cold-through.html

----------

2005 Chrysler PT Cruiser: A/C Blows Warm?

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2009 Mercury Grand Marquis: A/C blows Cold From Defrost Vent Only?

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http://schematicsdiagram.blogspot.in/2012/04/ac-not-blowing-through-vents-on-2007.html

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Passenger side temperature is warm air out of dash vents?

http://schematicsdiagram.blogspot.in/2012/04/passenger-side-temperature-is-warm-air.html

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These will help.

Thanks.

2helpful
2answers

A/C will only blow through defrost vents

Common question on this site. On late model cars, the vents are controlled by blend door motors. Small electric motors open and close doors to direct air flow.
Chances are you have a blend door that is stuck or a failed motor.
The default position is the defrost to make sure the windshield is always clear.
Someone will need to look behind the dash to see if all of the doors will move on demand.
1helpful
1answer

Ac vents not working

There is a blend door acuator which moves when u change your settings. Its a electric motor. Down under dash, Will need a mech and a heating and cooling diagram to find where the motor is,
0helpful
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Defrost blows constantly? How do i fix it?

does it blow through the defrost vent only when you switch to vent/floor or does it blow through defrost and vent/floor? is it a switch that is just electric or a manual lever that you slide? the manual type will have that problem if the diverter or the linkage behind the lever(in the dash behind the panel......may be able to access underneath) becomes broken or disconnected so that the air is diverted to defrost regardless where you move it.if you can get to it, you will see what is broken or maybe a fastenerr fell off.
0helpful
1answer

Dash vents will not blow air. Defroster and floor vents blow fine.

Is it a new vehicle? I had a new vehicle that had the same problem. Answer was that the holes weren't punched out of the vent.
14helpful
1answer

Heat wont blow through heater or defroster vents

common problem, check under dash by the gas pedal if control arms are muving went selecting from ac to heat cuz this it is the control for the vents to go from ac to heat and to defrost.
1helpful
2answers

Heat wont blow through heater or defroster vents

Had the same problem. believe it or not i changed the gas cap and got heat all around. something about pressure.
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