Instead of opening up a whole new thread I'm gonna add my question to this one. I've noticed that when I have my heat on, the temp gauge only goes just past the first mark. If I turn the heat off, it goes straight up within a few mins. If I turn the heat back on it will slip back down again to the first mark. Any ideas? The waterpump and thermostat were replaced and the coolant was supposedly flushed during that process when I had the t-belt done this summer. I also replaced the coolant sensor on the back of the motor about 2yrs ago with the green one.

 

If it is dropping back to the left towards the cooler side the blower fan is cooling the heater core that your coolant is flowing through. this could be what is going on

 

on my cari cleaned the heater core at 215,000miles and the heater worked ok but it was never really hot more like a warmish and took forever to heat up the car also the upper vents never got warm just cool so i had to use the bottom ones and they got pretty warm but never worked rigth

 

There might still be something clogging the heater core or it could be time for it to be replaced. I'd recommend using the CLR to clean it out at least every other year. This is the third time I've had heat issues.

 

Woot! My first self-repair job on my Audi was a sterling success. I used ImTheDevil's suggestions and it worked perfectly for me. I even took pictures, thinking that if nobody has done a DIY of it, I could.

I got all the supplies at Fleet Farm, and used 3/4" heater hose. This required a little customizing to get the ends of the heater hose to fit on the 2-liter pop bottles, but they went right on the heater core plugs and didn't need clamps to keep them there.

Oh yeah, one funny thing happened. I decided that if hot water was good, boiling water would be better. Well, upon pouring the boiling water into the pop bottle, the pop bottle shrank about 30%! So, I recommend very hot water, but not boiling.

Anyway, I've got much better heat than I did before, although there wasn't much in the way of crud or chunks that came out.

Even better, all the supplies, including the catch pan, cost me $32. Last year, the dealer did this for me for the whopping sum of $140.

So happy that I did this myself. Thanks for all the help and encouragement you give the newbies on this forum. It's much appreciated!

Next project, front brake pads!

 

^^^
Great to hear. Definitely get the pics up and make a DIY as this is a common issue.

 

Awesome and glad to hear it worked. And yeah it seems like suddenly there's a ton of heater core-related issues. I don't ever remember seeing this many in such a short span of time.

 

What do you mean by this? Are you saying the blower motor (I'm guessing the fan that blows the air through the vents) is running too much causing the drop in temps? How would I fix this?

 

Well, it is getting a bit colder up here in the north country, so that's probably why we're all coming out of the woodwork now.

 

the fan blows air through the heater core. you have coolant going through the heater core. the fan on the blower is helping to cool the coolant a little. That is why when you are in traffic and you car starts to over heat in the summer to turn the heat on for that little help to keep the coolant at a lower temp.