2014 b8.5 A4 no heat in cabin issue unless above idle rpm..

[moieser]

no heat in cabin unless above idle rpm... I've topped off coolant 4-5 times after a coolant flush... tried all ways of getting air bubbles it's puffing white smoke at idle, holds proper operating temperature.. no codes, don't really know what to do. fans wont turn on though.. i've noticed but its cold ambient temp atm.. something to do with fan?

[MongoMcG]

Fuses checked? Check the fan's electrical connector (at the fan, remove glovebox). Debris can get into the fan and jam it up. I've not removed the fan, but it apparently is easy to do for a visual inspection. Lastly, I do not know if the Audi blower fan has the large resistor that other manufacturers use, but our old Saab went through four of those, which kills the blower motor until the resistor is replaced.

[moieser]

I already replaced the blower motor and resistor it isn't that, it's something to do with the coolant system and i only get heat on throttle..


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[findalex]

could be a clogged/restricted heater core.

if it worked before the coolant flush, it's probably an air bubble.

try parking on an incline and idle. if the coolant level goes down, then you still have air bubbles.

when i flushed my coolant, i just kept driving and checked the coolant level daily until it stopped going down.

https://www.youtube.com/watch?v=NozqoyhUtAI

[moieser]

could be a clogged/restricted heater core.

if it worked before the coolant flush, it's probably an air bubble.

try parking on an incline and idle. if the coolant level goes down, then you still have air bubbles.

when i flushed my coolant, i just kept driving and checked the coolant level daily until it stopped going down.

https://www.youtube.com/watch?v=NozqoyhUtAI

thanks how many times did you top off?..


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[findalex]

I don't remember. Maybe over the course of a week, so 4 - 5 times.


Turning the heat on full, park it on an incline so the coolant reservoir is at the highest point should help.

[Theiceman]

I've never had an issue refilling coolant at all..
how did this start ?.

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[MongoMcG]

There is a tool to do a coolant refill. It uses a vacuum to draw coolant into the block and heater core and works a treat. Schwaben makes a knock-off version for 75 bucks (that's the one I use), and the Baum version is $160. They can work with either a fluid extractor (another nifty tool) or an air compressor.

[moieser]

There is a tool to do a coolant refill. It uses a vacuum to draw coolant into the block and heater core and works a treat. Schwaben makes a knock-off version for 75 bucks (that's the one I use), and the Baum version is $160. They can work with either a fluid extractor (another nifty tool) or an air compressor.

Yeah I saw something similar used on fcp euro videos and might have to give it a shot, thanks mate


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[moieser]

I've never had an issue refilling coolant at all..
how did this start ?.

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Started here : B8.5 A4 2014 Help with coolant temp sensor / Intake air system
https://www.audizine.com/forum/showpost.php?p=14868413

Managed to stop the overheating, but now concerned that there's still air and coolant keeps dropping in the resovoir, I'm going to continue topping it off like some people reccomended but there's no visible leaks.. There is however white smoke coming out of the exhaust like i mentioned so i hope it's not head gasket. I did do a coolant flush about a week ago and used a ton of diluted water with the heat on and all that, bled the heater core hoses and noticed there wasn't much flow to the heater core at all. Maybe gonna replace my waterpump/thermostat along with the coolant temp sensor and all the hoses. Even replace resovoir, and the cap. Might be my best option.


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[moieser]

[QUOTE=moieser;14872237]Started here : B8.5 A4 2014 Help with coolant temp sensor / Intake air system
https://www.audizine.com/forum/showpost.php?p=14868413

Managed to stop the overheating, but now concerned that there's still air and coolant keeps dropping in the resovoir, I'm going to continue topping it off like some people reccomended but there's no visible leaks.. There is however white smoke coming out of the exhaust like i mentioned so i hope it's not head gasket. I did do a coolant flush about a week ago and used a ton of diluted water with the heat on and all that, bled the heater core hoses and noticed there wasn't much flow to the heater core at all. Maybe gonna replace my waterpump/thermostat along with the coolant temp sensor and all the hoses. Even replace resovoir, and the cap. Might be my best option.. then use the schwaben tool with an air compressor to fill it back up properly with no air.


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[MongoMcG]

I was just researching no/low heat for the A3, and a known issue is sludge or some such in the heater hoses. I cannot say if it is an issue in the A4 system, but since you are gonna deep dive it will be worth having a look to see if the flush cleaned them out enough. Issues also exist on the A3 (and perhaps the A4?) with the air flow doors (or the motors that operate them). On the A3 I turned on the recycled air switch on the climate control panel and warm air started to blow (for now ). There is a diagnostic section in the FSM titled, D3E800C3A16-Heating__Ventilation_and_Air_Conditioning.pdf

If the white smoke is concerning then keep an eye out for oil level, milky oil (coolant contaminated), or oily coolant in the reservoir. If you'd like to be more certain then get a leak down tester (Harbor Freight sells a cheap one that is adequate). There are plenty of videos that cover doing the leak down test (differs from a compression test - the engine doesn't move during the test), but basically you are looking for overall pressure holding power of the assembly and differentials between cylinders. But there is a lot more you can learn during a leak down test by listening to various parts of the engine. Use a length of fuel or vacuum hose as a mechanic's stethoscope - open and listen down the dipstick tube and you will probably hear a high pitched hiss. That's air escaping from the cylinder into the crankcase, and a little bit (past the rings) is normal. Low pitch, or what sounds like a lot of air is bad. Next, remove the air duct at the throttle body, open the throttle body and stick the 'stethoscope' in there. If the cylinder is indeed at TDC then it should be quiet. If there is hiss then an intake valve is leaking or burnt. Checking the exhaust valves for leaks is a bit of a pain - you can remove the pre-cat O2 sensor to get the hose in a listenable spot, but even then it's tough to hear. That's all cool, but the reason I'm suggesting the leak down tester here is for your concern over the head gasket. A leaking head gasket will reveal itself during the leak down test as either bubbles in the coolant reservoir or air escaping into another cylinder (listen through spark plug hole). Also, if your spark plugs seem super clean you might be getting coolant in the combustion chamber. One last thing - compression can be lost through a cracked block as well - either into another cylinder or into the crankcase.

[moieser]

I was just researching no/low heat for the A3, and a known issue is sludge or some such in the heater hoses. I cannot say if it is an issue in the A4 system, but since you are gonna deep dive it will be worth having a look to see if the flush cleaned them out enough. Issues also exist on the A3 (and perhaps the A4?) with the air flow doors (or the motors that operate them). On the A3 I turned on the recycled air switch on the climate control panel and warm air started to blow (for now ). There is a diagnostic section in the FSM titled, D3E800C3A16-Heating__Ventilation_and_Air_Conditioning.pdf

If the white smoke is concerning then keep an eye out for oil level, milky oil (coolant contaminated), or oily coolant in the reservoir. If you'd like to be more certain then get a leak down tester (Harbor Freight sells a cheap one that is adequate). There are plenty of videos that cover doing the leak down test (differs from a compression test - the engine doesn't move during the test), but basically you are looking for overall pressure holding power of the assembly and differentials between cylinders. But there is a lot more you can learn during a leak down test by listening to various parts of the engine. Use a length of fuel or vacuum hose as a mechanic's stethoscope - open and listen down the dipstick tube and you will probably hear a high pitched hiss. That's air escaping from the cylinder into the crankcase, and a little bit (past the rings) is normal. Low pitch, or what sounds like a lot of air is bad. Next, remove the air duct at the throttle body, open the throttle body and stick the 'stethoscope' in there. If the cylinder is indeed at TDC then it should be quiet. If there is hiss then an intake valve is leaking or burnt. Checking the exhaust valves for leaks is a bit of a pain - you can remove the pre-cat O2 sensor to get the hose in a listenable spot, but even then it's tough to hear. That's all cool, but the reason I'm suggesting the leak down tester here is for your concern over the head gasket. A leaking head gasket will reveal itself during the leak down test as either bubbles in the coolant reservoir or air escaping into another cylinder (listen through spark plug hole). Also, if your spark plugs seem super clean you might be getting coolant in the combustion chamber. One last thing - compression can be lost through a cracked block as well - either into another cylinder or into the crankcase.

Drove it today, heat was fine, resovoir dropped though.. gonna let it cool down and top it off.


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[moieser]

I was just researching no/low heat for the A3, and a known issue is sludge or some such in the heater hoses. I cannot say if it is an issue in the A4 system, but since you are gonna deep dive it will be worth having a look to see if the flush cleaned them out enough. Issues also exist on the A3 (and perhaps the A4?) with the air flow doors (or the motors that operate them). On the A3 I turned on the recycled air switch on the climate control panel and warm air started to blow (for now ). There is a diagnostic section in the FSM titled, D3E800C3A16-Heating__Ventilation_and_Air_Conditioning.pdf

If the white smoke is concerning then keep an eye out for oil level, milky oil (coolant contaminated), or oily coolant in the reservoir. If you'd like to be more certain then get a leak down tester (Harbor Freight sells a cheap one that is adequate). There are plenty of videos that cover doing the leak down test (differs from a compression test - the engine doesn't move during the test), but basically you are looking for overall pressure holding power of the assembly and differentials between cylinders. But there is a lot more you can learn during a leak down test by listening to various parts of the engine. Use a length of fuel or vacuum hose as a mechanic's stethoscope - open and listen down the dipstick tube and you will probably hear a high pitched hiss. That's air escaping from the cylinder into the crankcase, and a little bit (past the rings) is normal. Low pitch, or what sounds like a lot of air is bad. Next, remove the air duct at the throttle body, open the throttle body and stick the 'stethoscope' in there. If the cylinder is indeed at TDC then it should be quiet. If there is hiss then an intake valve is leaking or burnt. Checking the exhaust valves for leaks is a bit of a pain - you can remove the pre-cat O2 sensor to get the hose in a listenable spot, but even then it's tough to hear. That's all cool, but the reason I'm suggesting the leak down tester here is for your concern over the head gasket. A leaking head gasket will reveal itself during the leak down test as either bubbles in the coolant reservoir or air escaping into another cylinder (listen through spark plug hole). Also, if your spark plugs seem super clean you might be getting coolant in the combustion chamber. One last thing - compression can be lost through a cracked block as well - either into another cylinder or into the crankcase.

No more loss to resorvoir.. I topped it off one last time and theres now heat in the cabin.

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[MongoMcG]

That's good news.