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  1. #1
    Active Member Two Rings
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    Audi A4 Heat not working at idle

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    Hey guys.

    My car just hit 70,000 miles. I have service due in a few days. I am planning on holding the timing belt/water pump to the 80,000 miles service. My car has been running perfectly for quite some time now. A couple of days ago, I turned on my car in the morning (a usual day) and let it sit there for 10 mins while I was getting ready to leave for work. I do this everyday in wintertime, turn on the ignition and let the car and the engine heat up before I start driving.

    So when I came back in to the car after 10 mins, I realized that the inside was heated enough. Its a regular routine for me so I know exactly what me car feels like after 10 mins. I drove off to work, everything seemed fine. Same thing happened in the evening. No heating during idle, but the car got warm enough while driving. I can easily conclude that the heat is definately not working when the car is sitting idle. I could set the temprature to HI and still nothing. If I rev the engine up to 3-4k while the car is in neutral, I can feel the heating coming from the blowers, but when I let go, it slowly becomes cool again.

    Can someone please tell me what could be going on? I run the car stock pretty much and when weird things happen out of no where, it just really ticks me off. Any help is much appreciated. Thank you.

  2. #2
    Veteran Member Four Rings italia8287's Avatar
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    Jul 23 2008
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    New York

    had the same problem on my B7. dealership said it was an air bubble in the system. they took care of it and the heat has been fine ever since...
    2007 QMT6 Ti S-Line
    NorthEastRegionDubs

  3. #3
    Active Member Two Rings
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    Jul 20 2010
    AZ Member #
    61673
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    KISSIMMEE, FL

    Yep Air Buble could be in your Heater Core. I fixed this in my car last week. Take the two hoes off the ones that go to your Heater core. At the back of the engine bay. Get a Wet Vac and a Hose and suck water throught the heater core which will also suck out any Air Bubbles in there.

  4. #4
    Active Member Two Rings
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    Eatontown NJ

    I am what you would call a "newbie" when it comes to working under the hood. Could anyone post a link to a DIY that might show where theyse hoses are? Sorry

  5. #5
    Established Member Two Rings zanadu's Avatar
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    Jun 09 2009
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    San Jose, CA

    having the exact same issue

  6. #6
    Veteran Member Four Rings diagnosticator's Avatar
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    Aug 26 2005
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    Seattle, WA

    The upper heater hose from the heater can be seen in the plenum under the windshield. To remove any air trapped in the heater core, first fill up the coolant reservoir and leave the cap off. Next, using vice grips, or better, hose clamp plyer, loosen and slide the spring clamp on the hose connection with the metal tube, to the rear, then carefully work the hose toward the rear, stopping when the hole in the metal tube is uncovered by the hose. With the head pressure from the coolant in the reservoir, the air will be pushed out of the relief hole near the end of the metal tube. When solid coolant flows from the relief hole, without any air bubbles, slide the hose back onto the metal tube all the way and reinstall the spring hose clamp. Refill the coolant reservoir, then replace and tighten the cap. Done.
    Last edited by diagnosticator; 01-16-2011 at 11:56 PM.
    Vorsprung durch Technik

  7. #7
    Senior Member Three Rings parm104's Avatar
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    Jul 06 2005
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    7138
    My Garage
    2009 Audi A4 3.2L Quattro
    Location
    Vancouver

    My car is in the shop for the exact same issue...My shop is saying that I may need a new heater core which is apparently a pain in the ass because it takes 4-5 hours to have that replaced :s

  8. #8
    Senior Member Three Rings 1CleanB6's Avatar
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    Oct 17 2010
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    03 Dlphn Grey B6 1.8t 5MT Quattro
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    having same problem as well. but i have a coolant leak, i think after the leak is fixed and i get a nice flush i will be fine, b/c when i top off the coolant and drive a little it heats up and stays hot.

  9. #9
    Veteran Member Four Rings A4OrlandoB6's Avatar
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    Aug 03 2008
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    Gainesville/Orlando, Florida
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    there are so many threads about this and i hate to keep them going but im still having this problem, even after a flush & fill. i think it could be possible that a lot of us have leaks that we dont know about. common ones are the J-plug by the thermostat, the rear coolant flange, and thermostats themselves. they're just a PITA to find.

    Parm, if you are or have any interest in being tech-savvy, the heater core isn't daunting, it just requires attention and focus. it will save you almost $1000.
    -David

    2004 Audi A4 1.8T - big turbo and some stuff

    2003 Audi A4 1.8TQM - RIP

  10. #10
    Veteran Member Four Rings drjonez's Avatar
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    Oct 27 2009
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    2003 A4 Avant 1.8tQ0A3, '72 Nova
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    Quote Originally Posted by parm104 View Post
    My car is in the shop for the exact same issue...My shop is saying that I may need a new heater core which is apparently a pain in the ass because it takes 4-5 hours to have that replaced :s
    Not so. Please search and read the replacement DIY. It is a 2h job MAX.
    '03 A4 Avant 1.8tQ0A3GT2871R

    Function > Form

  11. #11
    Senior Member Three Rings parm104's Avatar
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    Jul 06 2005
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    2009 Audi A4 3.2L Quattro
    Location
    Vancouver

    funkymillah I apologize in advance for thread jacking however any information related to my problem may help you as well.

    My shop just called me and told me that either it's my water pump that may not be working properly or it's my heater core that is blocked.

    They told me that the coolant in my coolant reservoir will continuously go down and then back up and while that happens, my heat also goes down and up.

    So what could be the issue? Is it a blocked heater core or does this sound like a water pump/thermostat issue? Thanks!

  12. #12
    Veteran Member Four Rings yung turbo's Avatar
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    Feb 19 2008
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    2005 A4 1.8T Qtip, 2008 A4 Avant S-Line 2.0T Qtip
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    NYC/DE

    Quote Originally Posted by parm104 View Post
    funkymillah I apologize in advance for thread jacking however any information related to my problem may help you as well.
    My shop just called me and told me that either it's my water pump that may not be working properly or it's my heater core that is blocked.
    They told me that the coolant in my coolant reservoir will continuously go down and then back up and while that happens, my heat also goes down and up.
    So what could be the issue? Is it a blocked heater core or does this sound like a water pump/thermostat issue? Thanks!
    if your car is doing this in the video then its you waterpump because this is the video i made that my car was doing
    TuRboK1ng
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  13. #13
    Established Member Two Rings zanadu's Avatar
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    Jun 09 2009
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    San Jose, CA

    Quote Originally Posted by diagnosticator View Post
    The upper heater hose from the heater can be seen in the plenum under the windshield. To remove any air trapped in the heater core, first fill up the coolant reservoir and leave the cap off. Next, using vice grips, or better, hose clamp plyer, loosen and slide the spring clamp on the hose connection with the metal tube, to the rear, then carefully work the hose toward the rear, stopping when the hole in the metal tube is uncovered by the hose. With the head pressure from the coolant in the reservoir, the air will be pushed out of the relief hole near the end of the metal tube. When solid coolant flows from the relief hole, without any air bubbles, slide the hose back onto the metal tube all the way and reinstall the spring hose clamp. Refill the coolant reservoir, then replace and tighten the cap. Done.
    What is this metal tube you are referring to, and you are are doing all this with the car running and the system pressurized?

  14. #14
    Active Member Two Rings Bean5's Avatar
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    Dec 09 2010
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    stafford uk

    I had the same problem, tool it to the garege for a new water pump, and they also noticed the thermostat housing was leaking, worth a look

  15. #15
    Senior Member Three Rings parm104's Avatar
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    Jul 06 2005
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    7138
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    2009 Audi A4 3.2L Quattro
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    Vancouver

    My hesitation with replacing the water pump is that I have already put in a new metal pump about 10,000KMs ago. I don't see how it would've already broken

  16. #16
    Senior Member Three Rings 1CleanB6's Avatar
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    Oct 17 2010
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    03 Dlphn Grey B6 1.8t 5MT Quattro
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    Lawrenceville,GA
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    just found out that my leak is also coming from my water pump. ill just wait until i do my timing belt soon to replace it.

  17. #17
    Active Member Two Rings Bean5's Avatar
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    stafford uk

    why not just do your timing belt and water pump now before it gets worse and corses more damge?

  18. #18
    Veteran Member Four Rings yung turbo's Avatar
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    Feb 19 2008
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    2005 A4 1.8T Qtip, 2008 A4 Avant S-Line 2.0T Qtip
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    NYC/DE

    Quote Originally Posted by parm104 View Post
    My hesitation with replacing the water pump is that I have already put in a new metal pump about 10,000KMs ago. I don't see how it would've already broken
    because its a well known thing that it your gonna replace the waterpump, then do the timing belt along with it? did you replace your timimg belt as well?
    TuRboK1ng
    You Are All Witnesses
    And The Yankees WIIIIIIIIIIIIIIIIIIIIIIIIIIN
    The Yankeeeeeeeeeeeees WIIIIIN!!!!!!!!
    !

  19. #19
    Senior Member Three Rings parm104's Avatar
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    Jul 06 2005
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    2009 Audi A4 3.2L Quattro
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    Vancouver

    Quote Originally Posted by yung turbo View Post
    because its a well known thing that it your gonna replace the waterpump, then do the timing belt along with it? did you replace your timimg belt as well?
    Well it was doing something similar to your video but my car was not overheating so I am going to rule out the water pump.

    And yes, that's why my water pump was replaced last year. I had the whole timing belt job done and the new water pump put in.

  20. #20
    Veteran Member Four Rings diagnosticator's Avatar
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    Aug 26 2005
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    Seattle, WA

    The metal tube is what the rubber hose is attached to, and has the air bleed hole that is uncovered by sliding the hose almost all the way off of. The engine in NOT running and must be cooled down when bleeding the air from the heater.
    Vorsprung durch Technik

  21. #21
    Active Member One Ring
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    Sep 17 2009
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    Location
    Toronto

    I had the same problem and did the air bubble purge and everything. Turns out the heater core was clogged. Ran some CLR in there and left it for ~5 mins. Flushed it with a hose and its been working fine since.

  22. #22
    Active Member Two Rings
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    Eatontown NJ

    Sorry I have been busy. A little update: My coolant had dipped below the MIN level (a significant amount). My car has never over heated up on me, infact I have never seen the needle go past the middle level. There is obviously a slight coolant leak (my guess would be the water pump), but I am holding off changing the timing belt and the pump till 80,000 miles. I might just end up trading the car in for a newer A4 before that.

    Anyway, so I filled up the coolant to the required level and now my heat is working fine. It just feels like its not as good as before or maybe I am just paranoid but its working fine for now.

  23. #23
    Veteran Member Three Rings PhunkFX's Avatar
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    Oct 11 2005
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    Hudson Valley, NY

    Quote Originally Posted by diagnosticator View Post
    The upper heater hose from the heater can be seen in the plenum under the windshield. To remove any air trapped in the heater core, first fill up the coolant reservoir and leave the cap off. Next, using vice grips, or better, hose clamp plyer, loosen and slide the spring clamp on the hose connection with the metal tube, to the rear, then carefully work the hose toward the rear, stopping when the hole in the metal tube is uncovered by the hose. With the head pressure from the coolant in the reservoir, the air will be pushed out of the relief hole near the end of the metal tube. When solid coolant flows from the relief hole, without any air bubbles, slide the hose back onto the metal tube all the way and reinstall the spring hose clamp. Refill the coolant reservoir, then replace and tighten the cap. Done.
    Ok, how about I tried doing this and there was NO coolant coming out of either the rubber hose or the metal pipe. I took the hose right off. The car was up to temp, the cap was off the reservoir, the reservoir was full, and alas, NO coolant.

    My car will only make heat if I boost the shit out of it. Like WOT full psi in 3rd gear to red line when the car is up to temp. Then I start to get heat. I'm so tired of this no heat crap. Never had this issue before.
    -Ricky

    2003 VW Jetta TDI 5MT

  24. #24
    Veteran Member Four Rings diagnosticator's Avatar
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    Aug 26 2005
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    Seattle, WA

    In this situation, more head pressure is most likely needed to push the air upward in the heater core, as replacement coolant fills the heater core from the lower heater hose. First, allow the engine to cool down. Next, to create more head pressure, reinstall the reservoir tank cap fully tight, then remove the small bleed hose at the top of the reservoir, plug the small bleed hose with a bolt and a hose clamp. Next, use an air pressure regulator on a compressor set to ~10 psig max, and with an air nozzle and a length of 3/8" ID rubber hose clamped on the nozzle and the hose barb on the tank, apply the regulated air pressure into the reservoir tank. (Any low air pressure source can be used to pressurize the reservoir tank, like a bicycle tire pump, for example.) With the pressure applied to the tank, repeat the air release procedure from the upper heater hose, until solid coolant flows from the bleed hole in the metal tube then slide the heater hose back onto the tube and replace the heater hose clamp. Next, remove the air nozzle from the tank and reinstall the bleed hose, refill the reservoir tank, then test drive.
    Last edited by diagnosticator; 01-24-2011 at 11:11 AM.
    Vorsprung durch Technik

  25. #25
    Veteran Member Three Rings PhunkFX's Avatar
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    Oct 11 2005
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    Hudson Valley, NY

    Thank you!
    -Ricky

    2003 VW Jetta TDI 5MT

  26. #26
    Established Member Two Rings swiderek's Avatar
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    Jan 10 2011
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    Oak Lawn, IL

    Same situation happened to me 2 days ago but the temp outside was 1*F. Usually my A4 blows hot air when I'm half way to work ( 30min commute ) when I drive or at idle. Went to the shop and was told it's normal for audi when it's very cold. I call it BS, none of my previous ( USDM, JDM ) cars had that problem but... Next day on my way to school ( 40min drive ) same thing but after like 30min of driving heat was working perfectly fine even at idle. Weird...

  27. #27
    Veteran Member Four Rings diagnosticator's Avatar
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    I forgot to mention that the small bleed hose, must be plugged when disconnected from the reservoir tank, to prevent loss of coolant from the hose when the system is pressurized with ~10 psig. In addition, any low air pressure source can be used to pressurize the reservoir tank, like a bicycle tire pump for example. I added the edit to the post above.
    Last edited by diagnosticator; 01-24-2011 at 11:12 AM.
    Vorsprung durch Technik

  28. #28
    Veteran Member Four Rings diagnosticator's Avatar
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    I agree, it's unlikely the pump, since a metal pump has already been installed recently.
    Vorsprung durch Technik

  29. #29
    Veteran Member Four Rings diagnosticator's Avatar
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    Quote Originally Posted by shmily View Post
    I had the same problem and did the air bubble purge and everything. Turns out the heater core was clogged. Ran some CLR in there and left it for ~5 mins. Flushed it with a hose and its been working fine since.

    A clogged heater core is unusual if not practically very unlikely unless the cooling system has not been maintained properly and allowed to get dirty from not enough G12 in the coolant.
    Vorsprung durch Technik



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