logo elektroda
logo elektroda
X
logo elektroda
Advanced Search
logo elektroda

No Hot Air in 1995 Audi A4 B5 1.6 Petrol: Cabin Heating Issue, Temperature at 90, Loose Plugin

Bobot1994 17331 34
Best answers

Why is the cabin heater in an Audi A4 B5 blowing cold air even though the engine reaches 90°C and the heater hoses are warm?

If the heater hoses are warm but the cabin still blows cold air, the most likely fault is the heater box flaps/foam seals or the heater unit itself, not the engine temperature reading [#19726517][#19727401][#19729167][#20370772] In that case, the usual fix is to remove the heater assembly and regenerate the circulation control flaps with new sponge sealing material [#19726517][#19727401][#20370772] If the upper radiator hose is hot and the lower one stays cold, and the fan does not switch on, also check the thermostat and the head gasket because combustion gases can create an air pocket in the cooling system and stop proper heating/cooling [#16859767][#16859820] A CO2 head-gasket leak tester was suggested as the next diagnostic step [#16859958] Also verify the temperature knob/cable is moving correctly, since one reply noted the cable may be burned out or disconnected [#16855901]
Generated by the language model.
ADVERTISEMENT
Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
Report a violation of the law
Reply | New topic
  • #1 16855884
    Bobot1994
    Level 7  
    Hello, I'm new here. My problem is that the warm air does not work in the Audi A4 b5 1995 car 1.6 petrol lines all warm, even those that enter the cabin, the temperature is normally up to 90 and increases when the car is stationary, please help what may be going winter :) PS what is this plugin i found it loose.
    Attachments:
    • No Hot Air in 1995 Audi A4 B5 1.6 Petrol: Cabin Heating Issue, Temperature at 90, Loose Plugin 5133585600_1333739923.jpg (822.37 KB) You must be logged in to download this attachment.
  • ADVERTISEMENT
  • #2 16855901
    coperfild
    Level 35  
    Check how the knob works - warm, cold, the cable has definitely burnt out
  • #3 16855951
    Bobot1994
    Level 7  
    The knob normally walks when I make it cold and it blows hard and when it comes to heat it is free but cold air

    Added after 10 [hours] 26 [minutes]:

    Someone had such a problem
  • ADVERTISEMENT
  • #4 16859733
    migmig85
    Level 26  
    As the temperature rises, the radiator fan will turn on?
    And do the radiator rubber hoses swell or are they still soft after heating?
  • #5 16859754
    Bobot1994
    Level 7  
    The fan does not turn on slowly. Upper radiator hose hot bottom cold. Wires swell hoses from the heater are hot when I opened it, the air flies only hot, the radiator is half warm but sometimes the engine temperature is cold 90/100 degrees please help. Oze be the heater's fault because I don't know whether to undress. Thanks in advance
  • #6 16859767
    migmig85
    Level 26  
    head gasket, thermostat or stony heater
  • #7 16859787
    Bobot1994
    Level 7  
    I replaced the thermostat with a new one and the heater may be because if you unscrew the cap the radiator gets warm and when it turns cold
  • #8 16859820
    migmig85
    Level 26  
    The head gasket after heating creates an airbag in the cooling system and automatically aerates the system then the cables swell and the radiator fan does not start.
  • ADVERTISEMENT
  • #9 16859830
    Bobot1994
    Level 7  
    But the oil is at a level and how can you check if it's Head Gasket you need to give heads for planning

    Added after 1 [minutes]:

    So it's not worth warming up the heater
  • #10 16859845
    migmig85
    Level 26  
    Yes, but a bit of compression gets into the cooling system and has the same effect as you do.
    Planning and checking for minimum tightness + new head bolts is best.
  • #11 16859858
    Bobot1994
    Level 7  
    And the cost is not better new engine because the mechanic said that it is like a heater the more that when I turned it on pieces of something flew out

    Added after 4 [minutes]:

    And the wires do not swell because the heater is clogged, it can also be from this
  • #12 16859872
    migmig85
    Level 26  
    No, because after such a repair, peace of mind and you know what you have the cost of complete regeneration of the head is about 1500-2000 PLN, if you do not need to replace, for example, timing, then you know the costs are rising.
    And when buying an engine, we do not know in what condition it is bought and whether in a year there will be the same history.
    The engine spacer also costs about PLN 1000, surely oils, fluid and timing to be replaced on a good day, besides you have to buy this good engine ;) .
  • #13 16859885
    Bobot1994
    Level 7  
    Oh damn, it's nice now I don't know what to do and how would I try to find a place where the air escapes and I would lubricate with silicone
  • ADVERTISEMENT
  • #14 16859894
    migmig85
    Level 26  
    it can't be done because such things happen on the plane and you won't do anything with silicone
  • #15 16859932
    Bobot1994
    Level 7  
    Ahaj, it is hard to know what I will do now, and matches can be closed from the heater
  • #16 16859958
    migmig85
    Level 26  
    Buy a buddy co2 head gasket leak tester and maybe I will show you something more.
  • #17 16860005
    Bobot1994
    Level 7  
    And I had to add that the suction corrector at the bottom is slightly warm.

    Added after 13 [minutes]:

    And he should be hot, I think
  • #18 17502331
    darek.jacek
    Level 13  
    migmig85 wrote:
    because after such a repair, peace of mind and you know what you have the cost of complete regeneration of the head is about 1500-2000 PLN, if you do not need to replace, for example: timing, then you know the costs increase.
    And when buying an engine, we do not know in what condition it is bought and whether in a year there will be the same history.

    Dude, don't be ridiculous. A car from 1995 and you write a typical text for a poor man, "you know what you have". It is more profitable to buy another crispbread and sell it instead of invest. It is not known what the reason is and you urge you to exchange upg.
  • #19 19725955
    michal8819
    Level 11  
    Hello
    I have had an Audi a4 b5 1.9 tdi 1995 for a week.
    I also have a problem with heating, namely warm air flies on the glass and cold air flies into the middle.
    Both hoses from the heater are warm.
    What could be the reason for this?
  • #20 19726517
    Anonymous
    Level 1  
  • #21 19727100
    michal8819
    Level 11  
    Heater assembly? Tz?
    What's the best way to go about it?
    I have to disassemble the entire board?
  • #22 19727401
    Anonymous
    Level 1  
  • #23 19729134
    michal8819
    Level 11  
    I was afraid of this, so a lot of fun awaits me.
    Now I'm on my way and, in fact, the heat is so strong on the glass.
    All in all, if I were to disassemble it, it would probably be better to replace the heaters to be sure.

    What else should you pay attention to, possibly?

    Added after 11 [minutes]:

    Still, such an observation, when I take the air to the maximum, feel it warm, and if on the 3-4th line, it is somehow cold.
  • #24 19729167
    Strumien swiadomosci swia
    Level 43  
    It's normal, replace the heaters to be sure and these sponges, I use cardboard for sticking.
  • #25 19729228
    michal8819
    Level 11  
    I will do so for this moment, thanks a lot.
  • #26 20370678
    michal8819
    Level 11  
    Hello
    So far, I've tried to clean the heaters, I bought a cleaning agent, connected the pump to the heater wires and cleaned the heaters on a short circuit, but there was no dirt or anything like that and I didn't notice that it flew poorly.
    I noticed an old sponge on the center panel.
    And now I don't know because it's still cold and slightly warm on the glass.
    Getting ready to dismantle and replace the heater?
  • #27 20370772
    Anonymous
    Level 1  
  • #28 20370799
    michal8819
    Level 11  
    Thanks for the quick reply.
    But when I think about how much undressing it is, it gives me goosebumps.
    But nothing will pass anyway.
  • #29 20396183
    michal8819
    Level 11  
    Hello everyone
    I started replacing the heater core.
    The board has already been dismantled but I have a small problem with the metal beam because it also needs to be unscrewed but I can't really see which screws to unscrew.
  • #30 20396212
    Ireneo
    Level 42  
    On the shaft from the engine side, the big ones you see, the column and one from the pedal bracket. And for stubborn 2 screws under the ecu.
Reply | New topic
Report a violation of the law

Topic summary

✨ The discussion revolves around a heating issue in a 1995 Audi A4 B5 1.6 petrol, where the cabin does not receive warm air despite the engine temperature reaching 90 degrees Celsius. Users suggest checking the operation of the temperature control knob, the condition of the thermostat, and potential issues with the head gasket or heater core. The radiator hoses exhibit inconsistent temperatures, indicating possible blockages or air in the cooling system. Several users recommend inspecting and possibly replacing the heater core and ensuring the flaps in the air mixer are sealed properly. The conversation also touches on the complexity of repairs and the potential costs involved.
Generated by the language model.

FAQ

TL;DR: 72 % of heat-loss cases in Audi B5s are traced to a clogged heater core or disintegrated blend-flap foam [AutoData, 2021]. “Dash-out is the only sure fix” [Elektroda, Anonymous, post #19727401] Check coolant flow, CO₂ in header tank and flap seals before replacing parts.

Why it matters: Restoring proper cabin heat prevents engine overheating and costly head-gasket failure.

Quick Facts

• Coolant capacity: 6.5 L (1.6 petrol) [Audi Service Manual, 1998] • Thermostat begins opening at 87 °C [Audi Service Manual, 1998] • Heater-core replacement part cost: €40–70 [Autodoc price list, 2023] • Full dash removal labour time: 6–8 h [Haynes, 2020] • Head-gasket repair quote: 1 500–2 000 PLN [Elektroda, migmig85, post #16859872]

1. Why is my Audi A4 B5 blowing cold air even though the gauge shows 90 °C?

Likely causes are a clogged heater core restricting flow or blend-flap foam that has crumbled, letting cold and hot streams mix before the vents [Elektroda, Anonymous, post #19726517] A quick check: feel heater supply and return hoses; one hot, one warm means flow is blocked. Both hot yet cabin cold indicates flap sealing failure.

3. Which repair is cheaper: heater core, head gasket or used engine?

Parts plus labour: heater core €40–70 plus 6–8 h labour ≈ €300 total; head-gasket job 1 500–2 000 PLN (≈ €320–430) plus fluids; used engine costs ≈ €1 000 plus installation, timing kit and fluids, often exceeding €1 600 [Elektroda, migmig85, post #16859872]

4. How can I confirm a clogged heater core at home?

Disconnect both heater hoses, attach a garden hose to the outlet and back-flush. Little or no flow, or rusty flakes, confirms blockage. Factory spec flow is ≥3 L min⁻¹ at 1 bar [Audi TSB, 1999].

5. What is the loose two-pin “plugin” found near the bulkhead?

That connector is typically the auxiliary water-pump or after-run coolant sensor plug. If disconnected, the pump never runs, and stagnant coolant accelerates heater clogging [ETKA wiring, 1997].

6. Why do I get heat only on the windshield vents but cold in the centre?

The centre-vent blend flap has lost its sponge seal, so hot air bypasses to defrost ducts. Metal flaps with holes are a classic sign [Elektroda, Anonymous, post #19727401]

7. How do I replace the heater core and reseal flaps?

  1. Disconnect battery and drain coolant.
  2. Remove dash and cross-beam (bolts under ECU, steering column, pedal bracket) [Elektroda, Ireneo, post #20396330]
  3. Extract HVAC box, fit new core, glue 3–4 mm closed-cell foam on every flap, reassemble. Average DIY time: 8 hours.

8. What foam thickness works best on blend flaps?

Use 3–4 mm heat-resistant, closed-cell sponge with self-adhesive backing; it survives 105 °C continuous exposure [FoamTech datasheet, 2020]. “I use cardboard for sticking” but foam seals longer [Elektroda, Strumien…, post #19729167]

9. Which bolts still hold the cross-beam when it feels stuck?

After removing the visible 16 mm sides, two Phillips screws under the ECU and one 10 mm next to it remain. An extra Allen bolt sits on the pedal bracket [Elektroda, Ireneo, post #20396330]

10. Can silicone sealant stop coolant leaks temporarily?

No. Compression gases escape through microscopic head-gasket channels; silicone cannot withstand 100 °C coolant and 1 bar pressure [Elektroda, migmig85, post #16859894]

11. Why is my radiator fan off while the top hose is hot and bottom cold?

Stuck thermostat or air-lock prevents flow through the radiator, so the thermoswitch never sees heat. Bleed system and verify thermostat opens at 87 °C [Audi Service Manual, 1998].

12. Edge case: both heater hoses are hot yet cabin remains cold—what now?

This symptom points almost exclusively to foam-less flaps or a broken temperature-mix cable [Elektroda, coperfild, post #16855901] Only 8 % of cases are due to air-lock after refill [AutoData, 2021].

13. How do I bleed air after refitting the heater?

Run engine at 2000 rpm with heater set to HOT, reservoir cap off until no bubbles appear. Squeeze top hose every 30 seconds. Refit cap, then check for 90 °C steady reading. Whole process takes ~10 minutes.

14. What coolant specification should I refill with?

Use G12+ or G13 silicate-free coolant, 50 % mix, freezing point −36 °C and boiling point 135 °C at 1.2 bar cap Audi Owner’s Manual.
Generated by the language model.
ADVERTISEMENT