Is it possible to "unclog" a heater core? My wife's 2001 A4 1.8TQ with 202k miles is not producing any heat. I've searched, but did not find an answer if it can be "unclogged". The VAGCOM is not showing any fault codes at all. The engine temp is perfect and so is the oil temp. The car runs great otherwise. I don't think my wife has noticed it at all since I believe the great heated seats mask the issue.

So I am wondering, if I stick a water hose or air hose into the inlet of the heater core, is it possible to "blow out" anything that is clogging it? Otherwise, a heater core replacement seems like a HUGE job since the mechanic would have to remove the entire dashboard.

Thanks in advance!

 

You can definitely flush it; but you do it in the reverse direction. Hook up a water hose to the core outlet and then an extra bit of hose to the core inlet to drain, and let 'er rip.

Pulling the dash isn't all THAT bad, though...
http://i196.photobucket.com/albums/a...d/100_1509.jpg

 

Are you sure it isn't airlocked? Is the coolant-to-water ration strong enough? Heat control working correctly? Did you add any leak-stop that could have blocked up the heater core?

 

If I'm standing in front of the car, which one is going INTO the heater core again? The driver or passenger side hose?

 

Yes, the coolant/water ration is 50/50. No leak stops...

 

yea. my buddy just had to get this done to his truck by a shop. we tried doing it at home, but i think they can pressurize it at a shop or something, whatever they did it fixed it. you definately want to try to backflush it by going the opposite of normal flow.
Im not sure, but i think the hose closer to the driverside is the supply to the core, and the passenger side is the return? can anyone verify?

 

So we backflushed the heater core in the opposite direction of flow... Guess what? All this "sand like" sediment all came out... This was done numerous times (about 20 times) per my mechanic. But the result? For 2 hours of work, I have some serious heat in the car now. This surely beats getting a new heater core installed for $2000 or whatever the dealer wants to rape you by...

 

sweet - good to hear, dude.

 

Sorry to add to this thread with my problem but I couldn't resist in case this is my problem as well. I have an 02 A4 and the heat only comes on when I am at high speeds or if I rev the engine high. At idle, it gets cold again. So far I have gotten the coolant light on twice and it disappears after 30 seconds. I took it to the mechanic who checked the coolant level (so did I before I took it) and it seems normal. I checked the hose when the car is hot and running and the big hose is hot to the touch. The blower and auto temp keeps blowing and works as long as I am on the highway with high revs as I mentioned. Temp gauge is steady and in the middle. The mechanic also indicated that no error faults were picked up on the scanner apart from my washer motor which keeps blowing a fuse. He doesn't think the two are connected. The diagnosis seems to be that the impeller on the water pump could be worn out (that it used to be plastic before the design change) and therefore only seems to be efficient at high revs. This job is way too big for me and I am in Chicago with no heated garage anyway. You can imagine the cost and therefore in this case I might as well get the timing belt and stuff done even though I got 50K on the car.

Thermostat?
Heater core?
Agree with the diagnosis?

Thanks all.

 

See post #7