No heat from heater

[EamonnC]

Hello

I have a 54 plate Audi A4 1.9TDi estate & lately I'm not getting much heat from the heater. When the heat is set to high & the engine has warmed up I'm getting about 5% of the normal strength of heating being produced.

I've read a few sites online & the first things to check are to make sure the coolant is topped up & to make sure there is no air in the system which I have checked.

I was working today doing some electrical work at a guy's house & he is a mechanic who works from his rear garden garage. I asked him what he thought the fault might be & he said he would connect the diagnostic unit in to see if anything is logged. There were no fault codes reported & so he said he would look into the engine bay & let me know. After 30 minutes he said that he recommends having the thermostat replaced, he did that & the fault was still there. He showed me two rubber hoses that enter the dashboard from the engine bay & he said they were the entry & return hoses for the heater & that one hose was very hot & the other was slightly warm. He said that the fault sounds like the water pump is faulty & that it should be replaced. He also said to replace the cam belt as well at the same time, my car has done 163k miles.

I have reservation's about going ahead with this work until I have looked into the issue more. Could the rubber hose be blocked & so preventing the coolant from flowing freely?

I wondered if anyone on here has had a similar fault or any advice.

Thank you.

E

[calum]

If the car doesn’t overheat I would disregard the water pump.
Remove both hoses that you were shown and flush cold water through from each side, if the water you flush through is dirty then that’s all the problem was. Flush the whole system and renew coolant G13.


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[EamonnC]

If the car doesn’t overheat I would disregard the water pump.
Remove both hoses that you were shown and flush cold water through from each side, if the water you flush through is dirty then that’s all the problem was. Flush the whole system and renew coolant G13.


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Hi Calum

Thank your for your reply.

When you say flush cold water through is that at the point where the two hoses enter the dashboard from the engine bay? By the fresh water being dirty after being flushed through does it mean the original dirty water was blocking the hoses?

Thanks

E

[calum]

Yes at those hoses, the fresh water will push out any dirt or debris which is restricting the flow through the heater matrix.
Flush from the exit side first, the one on the drivers side then from the other side, don’t use too much pressure though.

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[A1EK]

The heat on our cars is a weak spot and there have been many people with issues. It took me weeks to resolve the issue, I lot of searching and trying different things, but it came down to flushing the core and removing the sludge as a result of a crushed oil cooler seal.

First is your coolant emulsified and sludgy? If so then you should check that your oil cooler is not leaking, replace the oil cooler rubber seal and flush the heater core and expansion tank. The best way to flush the heater core I found is to find the inlet and outlet pipes next to the battery at the back of the engine behind bulk head. Remove the clips and pull off the hoses, if they are tight, try pushing them first then pull off I think the top pipe is out and bottom is the inlet. Now heres the trick, if you can connet your garden hose to your house hot tap (I made an adaptor) this will greatly help disperse the gunk, connect to the inlet of your heater core and let the hot water flow through for a few mins. Now connect the hose to the outlet of the core to back flush, the gunk will come out of the inlet pipe now. Do this a couple of times then the same for the hoses you removed that go to the engine, you can open the radiator drain to allow the water to exit there.

Once you have flushed properly, clean your expansion tank, remove from the car by unplugging the cable and use a little washing up liquid or spirit to get rid of the gunk and flush out. Now re-connect the core hoses, close the radiator drain and fill the car with preferably distilled water or pre-mixed pink coolant to the correct concentration.

The challange now is to bleed the air from the coolant system, start the car with the heater on full then after a few mins pull back the inlet pipe at the core and you'll notice a small 2mm hole in the hose, this allow you to disperse air and keep the hose connected to the pipe. You are looking for a steady thin spray of coolant, but first you will see bubbles. Hopefully this should fix the no heat issue, if not then remove the engine plastic cover and there is a metal pipe on the right top of engine with either an Allen key or nut, loosen this when the engine is warm and allow the air out. Drive the car and repeat the process at the engine pipe, it took me a bout 3-4 times before all the air was gone and I had heat.

Good luck, if you get it right your car should start getting warm inside after 3 mins, and stay warm when sitting at the lights and not go cold !

[micheal balbrig]

The end result for a lot of these problems seem to be a new heater matrix,as the smaller tubes block up and refuse to clear with flushing.
Hopefully your problem clears or improves with flushing.