Audizine - An Automotive Enthusiast Community

Results 1 to 11 of 11
  1. #1
    Active Member One Ring
    Join Date
    Oct 16 2018
    AZ Member #
    429073
    Location
    Sacramento CA

    Coupe Quattro heater

    Guest-only advertisement. Register or Log In now!
    Trying to get the heater to work in my 1990 Coupe Quattro, so I have working fan, floor vent, defogger, and temperature adjustment. Noticing that itís vacuum operated actuators and such, Iím guessing somethings cracked or an actuator has failed. I canít seem to find where the vacuum is fed into the HVAC system. The heater valve operates in the engine bay, and I have coolant flowing in and out of the core, so itís not plugged, but canít get hot air to come out anywhere. Also, I can only get air to come out of the front facing dash vents when i go to the colder temperature range on the control. I want to take this thing to the snow so bad but no heat would be brutal. Ask any questions that would help you know more about the situation. Thanks

  2. #2
    Active Member One Ring
    Join Date
    Oct 16 2018
    AZ Member #
    429073
    Location
    Sacramento CA

    Side note, this is my first time using any sort of forum, so Iím not sure if I posted this in the right area. Lmk if I need to change anything

  3. #3
    Veteran Member Four Rings jbrentd's Avatar
    Join Date
    Oct 31 2005
    AZ Member #
    8580
    My Garage
    '91 Coupe Quattro, '97 4Runner
    Location
    Tulsa, OK

    Inside the airbox, there is a flap that directs the flow of air to the different vents. It was covered with some sort of foam tape from the factory and over time that foam start to deteriorate. The sheet metal flap has holes in it and when the foam tape goes, the flap doesn't do its job. Sounds like you need to rebuild the airbox. It's a common problem. Not a fun job, but worth the effort if you want a functioning HVAC system. If you do it, I would recommend replacing the heater core while the dash is out and replacing any vacuum lines that are bad.

    Here's a link to my build thread on MG where I took pictures during the job.

    https://www.motorgeek.com/viewtopic....665523#p665523

  4. #4
    Active Member One Ring
    Join Date
    Oct 16 2018
    AZ Member #
    429073
    Location
    Sacramento CA

    Once winter is over Iíll for sure pull the box and give it a refresh, but for now Iíd like to try to get some heat out of it, Iím super eager to take it to the snow this year and heat would be a huge plus. Iím guessing thereís a main source of vacuum to the hvac system, do you know where that is? And knowing that the actuators were vacuum I was considering that the diaphragms were bust, so thatís also my problem probably. I appreciate the pics that will definitely help expecially for the lack of DIY YouTube vids.


    Sent from my iPhone using Audizine

  5. #5
    Veteran Member Four Rings jbrentd's Avatar
    Join Date
    Oct 31 2005
    AZ Member #
    8580
    My Garage
    '91 Coupe Quattro, '97 4Runner
    Location
    Tulsa, OK

    Coupe Quattro heater

    Quote Originally Posted by Deleo View Post
    Once winter is over Iíll for sure pull the box and give it a refresh, but for now Iíd like to try to get some heat out of it, Iím super eager to take it to the snow this year and heat would be a huge plus. Iím guessing thereís a main source of vacuum to the hvac system, do you know where that is? And knowing that the actuators were vacuum I was considering that the diaphragms were bust, so thatís also my problem probably. I appreciate the pics that will definitely help expecially for the lack of DIY YouTube vids.


    Sent from my iPhone using Audizine
    Is the air that is coming out of the floor vents and defrost vents warm at all? If not, I would suspect you have air in the system or your heater core is clogged. If I remember correctly, the water circulates through the heater core all the time. Maybe @Ruffiano can give his thoughts...he's spent a lot of time on these old HVAC systems.

  6. #6
    Active Member One Ring
    Join Date
    Oct 16 2018
    AZ Member #
    429073
    Location
    Sacramento CA

    So no warm air but I verified coolant is flowing through each side of the core with a temp gun.


    Sent from my iPhone using Audizine

  7. #7
    Veteran Member Four Rings jbrentd's Avatar
    Join Date
    Oct 31 2005
    AZ Member #
    8580
    My Garage
    '91 Coupe Quattro, '97 4Runner
    Location
    Tulsa, OK

    This probably won't be too helpful, but just in case...there are several pages on how the climate control system works and the component locations.

    https://manuals.co/workshop/audi/cou...aining/3905/63

  8. #8
    Active Member One Ring
    Join Date
    Oct 16 2018
    AZ Member #
    429073
    Location
    Sacramento CA

    Another thing. Are you or did you convert to r134?


    Sent from my iPhone using Audizine

  9. #9
    Veteran Member Four Rings jbrentd's Avatar
    Join Date
    Oct 31 2005
    AZ Member #
    8580
    My Garage
    '91 Coupe Quattro, '97 4Runner
    Location
    Tulsa, OK

    Quote Originally Posted by Deleo View Post
    Another thing. Are you or did you convert to r134?


    Sent from my iPhone using Audizine
    Mine had been converted to r134a before I bought it...so, yes.

  10. #10
    Active Member One Ring
    Join Date
    Oct 16 2018
    AZ Member #
    429073
    Location
    Sacramento CA

    Image1544468999.871208.jpg
    Image1544469038.169446.jpg
    Update: managed to figure out my issue. The temperature control servo, I think the only servo thatís not vacuum, basically wasnít working. Pulled it off, operated the door manually, bam. Super hot heat. So in my case it wasnít an issue of a diaphragm that went bad it was an electric motor


    Sent from my iPhone using Audizine

  11. #11
    Veteran Member Four Rings jbrentd's Avatar
    Join Date
    Oct 31 2005
    AZ Member #
    8580
    My Garage
    '91 Coupe Quattro, '97 4Runner
    Location
    Tulsa, OK

    Glad to see you found the issue. There are a couple people parting out CQs if you need to find a new servo. Check Motorgeek, TheProjectPad or the Small Chassis group on Facebook.



Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


    © 2001-2018 Audizine, Audizine.com, and Driverzines.com
    Audizine is an independently owned and operated automotive enthusiast community and news website.
    Audi and the Audi logo(s) are copyright/trademark Audi AG. Audizine is not endorsed by or affiliated with Audi AG.