Question about 1999 GMC Sierra

1 Answer

Defrost and floor heat broke

Defrost floor and panel wont blow air

Posted by on

1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that got 5 achievements.

    Filmmaker:

    Uploaded 5 video answers.

    Greenhorn:

    A rookie expert who has answered 20 questions on their first day.

  • Expert
  • 72 Answers

Are you saying you don't have blower at all? Defrost, floor and panel are the only three separate modes you have. If it's not blowing at all and the fuses are good, check the wiring behind the glove box. There's a two wire plug with a large red wire just about center of the glove box opening that's known for burning out. If it is you'll see the burned spot on the connector or wont be able to disconnect it.

Posted on Jan 01, 2014

6 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

  • 13 Answers

SOURCE: 97 Sierra no heat on passanger defrost or floor

I assume you have the dual climate control feature on your truck. it sounds like you have door problems. The heating system has several doors inside the box and duct work that divert the air from defrost to face and feet...i'm not 100% sure if the ones in your truck are electronic or vaccum, but i think they are electronic. From time to time the actuators that control the door go out, as every electric motor does. You need to find the ones that have quit and replace them. It is possible that the arm(s) on the actuator(s) have broken loose from the doors and are working but not pushing or pulling the doors properly...if might help to remove the front seats...just to help save your back....working under the dash is hard on your body....and it take a good half day to remove the dash, so working under it is actually less work.

Posted on Mar 13, 2009

cadman000
  • 607 Answers

SOURCE: a/c and heater only blow air out of defrost

sounds like there is a vacuum leak, possibly under the hood.. Vaccumm is needed to change the mode doors.

Posted on Mar 30, 2009

bunnydawg
  • 5158 Answers

SOURCE: 2006 Envoy SLT air suddenly stopped blowing from vents

the resister block needs changing... oddly enough i'm unsure of what fan you are saying is not working.... if it's the front.. the resister block is located on the duct work under the dash for the air... near the fan... you will see a connector going into the side of the duct work. two screws and the block comes out... should be fairly obvious for the rear one but it will be near the fan.

Posted on Apr 16, 2009

alicantecoli
  • 22114 Answers

SOURCE: a/c and heater only blow air out of defrost

either a vacumn pipe is broken or the ends split so its not passing a vacumn to open the flaps,where they are and how to get to them i cant help because i have never worked on one as they are not here in spain.check the engine end first though .Look for some small rubber pipes running from the inlet manifold

Posted on May 30, 2009

  • 47 Answers

SOURCE: Floor heater won't work

With the key in the off position; remove the RDO BAT fuse for at least 10 seconds then replace the fuse; turn on or start the vehicle and try the A/C again. Removing the fuse should reset blend actuators.

Posted on Dec 11, 2009

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Need pitcure of vaccum lines on 1999 Ford Ranger v6 3.o air and heat blows only threw the defroster.


26392097-cvaukpwazi2vnl4fgradjhua-2-2.gif

Item Part Number Description 1 18A318 Vacuum Control Motor-, Panel/Defrost Door 2 18A478 Panel/Defrost Door (Full Vacuum Position) 3 - Defrost Air Flow 4 - Side Window Demister Air Flow 5 18B545 Temperature Blend Door (Full Heat Position) 6 19860 A/C Evaporator Core 7 19A813 Air Inlet Duct Door (Full Vacuum Position) 8 - Outside Air Inlet 9 18A318 Vacuum Control Motor-, Air Inlet Duct Door 10 - Recirculated Air Inlet 11 18527 Blower Motor 12 19A566 A/C Vacuum Reservoir Tank and Bracket 13 - Vacuum from the Engine Intake Manifold 14 19B888 A/C-Heater Function Selector Switch 15 - Vacuum to the 4x4 Hub Solenoids 16 18495 Water Diverter Valve (Full Vacuum Position) 17 18476 Heater Core 18 18A559 Floor/Panel Door (Full Vacuum Position) 19 - Floor Air Flow 20 18A318 Vacuum Control Motor-, Floor/Panel Door 21 - Panel Vent Air Flow

Dec 09, 2016 | Ford Ranger Cars & Trucks

1 Answer

Why wont my 2001 ford windstar blow out of vents ? only on defrost?


Air Flow Control
Air flow control is accomplished in the following manner:
  • Primary control is through the function selector knob , mounted on the heater function selector switch, which is part of the heater control .
  • The function selector knob has the following positions: OFF, PANEL, PANEL/FLOOR, FLOOR, FLOOR/DEFROST and DEFROST.
  • The heater function selector switch combines a vacuum selector valve with an internal electrical switch.
  • The vacuum selector valve directs source vacuum to various vacuum control motors (18A318) . Refer to the System Airflow Schematic and Vacuum Control Charts.
  • An internal single-pole electrical switch is also controlled by the selector. The switch controls the electrical supply to the heater blower motor switch (18578) .
  • The position of the function selector knob determines the manner in which the system will operate.
  • Each position of the function selector knob is detented for positive engagement.
  • You probably have a vacuum leak , Pull heater control panel an check for vacuum . A broke vacuum hose or The vacuum selector valve is bad ! Or check for a vacuum hose in the engine compartment being off somewhere !

Mar 08, 2015 | 2001 Ford Windstar

1 Answer

A/C wont blow out air from passager vents


Vent door may be broke in the closed position,what year and make,model is it.

Mar 24, 2013 | GMC Yukon XL Cars & Trucks

1 Answer

Heat and Air only blow on defrost and floor


The blend doors are controlled by small electric motors.
One of the motors could have failed, or the blend door is sticking.

Sep 26, 2012 | 2000 Chevrolet Silverado 2500

1 Answer

I HAVE A 2001 DODGE DURRANGO THE DEFROSTER IS NOT BLOWING ANY AIR OUT OF TOP OF DASH BUT SEEMS TO BLOW OUT OK ON ALL VENTS AND FLOOR


it sounds like the switch lever for the vents, floor and defrost is not switching the vent door that goes to the defroster hose. You need to pull the switch consol out loose from the dash and follow the cable for the defrost that goes to the hose for the defrost. You might also have a broke switch that won't pull the cable enough to open the air for the defrost hose.

Oct 15, 2009 | 2001 Dodge Durango

1 Answer

A/c and heater only blow air out of defrost


either a vacumn pipe is broken or the ends split so its not passing a vacumn to open the flaps,where they are and how to get to them i cant help because i have never worked on one as they are not here in spain.check the engine end first though .Look for some small rubber pipes running from the inlet manifold

May 30, 2009 | 2005 GMC Sierra 1500 Hybrid

1 Answer

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.

Jan 18, 2009 | 1997 Chevrolet K1500

2 Answers

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.

Dec 05, 2008 | 1993 Chevrolet Corsica

Not finding what you are looking for?
1999 GMC Sierra Logo

87 people viewed this question

Ask a Question

Usually answered in minutes!

Top GMC Experts

yadayada
yadayada

Level 3 Expert

75744 Answers

Freddy

Level 3 Expert

1311 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22114 Answers

Are you a GMC Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...