How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Bob Your Own Question

Bob
Bob, Auto Tech
Category: Chevy
Satisfied Customers: 4087
Experience:  Plus 40 years GM, over 30 certified with Chevrolet, ASE certified Master Tech. (Expired, Retired)
2210118
Type Your Chevy Question Here...
Bob is online now
A new question is answered every 9 seconds

1995 suburban: fan works..blowing..fo bottom but other vents

Customer Question

1995 suburban heater and fan works blowing out fo bottom but other vents do not work
Submitted: 6 years ago.
Category: Chevy
Expert:  Bob replied 6 years ago.
Hello, need to know if the back side of your control panel had only wiring or if it also had a vacuum harness connected to it. That will determine which system you have and how we go about checking it out. Thanks
Customer: replied 6 years ago.
how can you tell
Expert:  Bob replied 6 years ago.
When you changed the control did you have to unhook any vacuum hoses made of rubber or was it just wiring connectors?
Customer: replied 6 years ago.
only wires
Expert:  Bob replied 6 years ago.

Good deal, thanks for the added info. This means that the reason the sir flow does not change is because one of the mode doors on the case is not opening up to allow the air flow to change. These door are controlled bu electric actuator motors that are connected to them and they in turn are controlled by the control panel that you have already replaced. Sometimes the actuators fail and sometimes the linkage that connects them to the door will fail or break. Once in a great while the problem will be inside the case with a door itself. You will need to look under the dash at the electric actuators and watch to see if they move when you change the control setting. If they do, then you know the problem is with the linkage or the door itself. If they do not move., then you will need to use a volt meter to see if the voltage going to them changes when you change the setting on the control panel. If the voltage changes, then the actuator itself is bad and will need to be replaced. You should only run into problems if the door itself has problems because then it is necessary to remove the complete HVAC case assembly to access and repair the doors. Below is a picture of what a mode door actuator looks like. This will give you an idea of what you are looking for. It is located just about in the center of the floor area on the HVAC case, under the dash. You may need to remove the plastic close out covers to access them. Thanks

Object Number: 258020  Size: SH

Bob, Auto Tech
Category: Chevy
Satisfied Customers: 4087
Experience: Plus 40 years GM, over 30 certified with Chevrolet, ASE certified Master Tech. (Expired, Retired)
Bob and other Chevy Specialists are ready to help you
Customer: replied 6 years ago.
Relist: I still need help.
the electric actuators has no movement. using the volt meter 3 wire connector wich wire do you test there is voltage with test light voltage remains the same on imput wire does resistance? actvater has been replaceed &blend door is moving manually by hand.
Expert:  Bob replied 6 years ago.

If the actuator has been replaced and the control panel also, there has to be a problem in the wiring between the panel and the actuator. One of those wires should change resistance or voltage reading as the control is changed to open the door with the actuator. I thought there was a factory bulletin on a wiring problem behind the dash on that year but have had no luck finding it. I will need to check with some other experts to see if they have any info on it. It looks from the diagram like the white wire is the one that should control the changing of the actuator.Thanks

Customer: replied 6 years ago.
we bought the truck used we did not get any factory bulletin since we bought it. will you let me know if you find out anything. my e-mail isXXX@XXXXXX.XXX
Expert:  Bob replied 6 years ago.
They did not issue a recall. I was trying to find a technical bulletin on it. And yes, I sure will let you know. I have requests out now and just waiting to hear from some of the other guys. Thanks
Bob, Auto Tech
Category: Chevy
Satisfied Customers: 4087
Experience: Plus 40 years GM, over 30 certified with Chevrolet, ASE certified Master Tech. (Expired, Retired)
Bob and other Chevy Specialists are ready to help you
Expert:  Bob replied 6 years ago.

Hello again, Our first comment was to check the link on the side of the actuator to see if it is broken, but I'm thinking you already did that. Then there was another comment from one fellow but again I think that is how I had you test it before, but will post it just in case. Thanks

The mode doors and the temperature doors are positioned in proportion to the variable voltage signal received from the HVAC control module. The temperature dial at the HVAC control module adjusts a rheostat which provides a voltage signal proportional to the dial position. CKT 733 (LT BLU) carries the voltage to the front temperature door motor. The front temperature door motor responds to the voltage signal. The mode dial at the HVAC control module adjusts a rheostat. The mode dial provides a voltage signal proportional to the dial position. CKT 454 (WHT) carries voltage to the front mode door motor. The front mode door motor responds to the voltage signal.

Have him backprobe white wire and turn mode knob and see if voltage changes it won't change unless plugged in (voltage drop)

Brown should have source and black 0 volts

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Last | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
< Last | Next >
  • http://ww2.justanswer.com/uploads/TI/tim37857/2011-10-28_23053_S6301814.64x64.JPG Tim's Auto Repair's Avatar

    Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
  • http://ww2.justanswer.com/uploads/DT/dt69nova/2012-6-15_234154_pic1.64x64.jpg Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    6870
    ASE Master Certification. GM World Class Certification
  • http://ww2.justanswer.com/uploads/ggrote1/2009-06-27_031011_me.jpg Gary's Avatar

    Gary

    Chevy Technician

    Satisfied Customers:

    5404
    15 years GM master tech
  • http://ww2.justanswer.com/uploads/testedtuff/2009-09-26_170108_pictures.jpg John's Avatar

    John

    Master A.S.E Automotive technician

    Satisfied Customers:

    4071
    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • http://ww2.justanswer.com/uploads/RO/rodcuda/2011-7-25_224114_Donhoff1.64x64.JPG Neal's Avatar

    Neal

    Chevy Mechanic

    Satisfied Customers:

    2306
    Shop Owner and Mechanic on multiple makes.
  • http://ww2.justanswer.com/uploads/goodwrench9124/2008-11-09_220838_dscf0007.jpg goodwrench9124's Avatar

    goodwrench9124

    ASE Certified Technician

    Satisfied Customers:

    2041
    Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
  • http://ww2.justanswer.com/uploads/DR/drivefast1971/2012-1-12_172422_0009051tQKh.64x64.jpg Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    1912
    18+yrs experience. State Inspector and Chevy Diagnostics