# 98.5 audi a4 only blowing cold air on heat



## vr lowlife (Dec 14, 2010)

Ok so i have a 98.5 A4 2.8 quattro. I done some research still cant seem to find the problem. So on all settings on the climate control it will only blow cold air. I have recently replaced the timing belt, water pump and thermostat. I made sure to keep the coolant reservoir was raised a few inches when I burped the system. The temperature Stays dead center and i have had no issues of it over heating. The floors do not get damp indicating a possible bad heater core and the cabin does not smell of coolant. I have also checked the send and return hoses for the heater core under the hood and both are hot after being driven which leads me to believe its not clogged. I dont believe it to be the flapper motor as i can here it moving as i change the temperature up and down so i am currently stumped. Has anyone had a similar issue? any in site would be greatly appreciated. Thanks


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## Eric D (Feb 16, 1999)

What you need to understand is that the return hose will get hot from coolant in the system.
It doesn't mean its circulating through the heater core, just that the coolant at the hose does reach operating temperature by means of convection.

Depending on the core design, plastic ends or aluminum they both get clogged.

Plastic version.










Aluminum version.


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## ismule (Mar 8, 2005)

*Heat*

Hello Lowlife

Having the same problem , changed belt ,water pump , heater core , idle pulley , and coolant flush , at low RPM under 1500 it starts blowing Cool air , but at 3000 RPM it is hot , . My guess is the new STOCK VW OEM water pump is faulty guessing that the pumps inpeller is under size , there is to much clearance from inpeller to pump body and the pressure is not great
Enough to push the coolant fast enough at low RPM . JUST A GUESS. 

I Bought the car new from VW in Dec. of 2001 and have 193000 on it know and still is a very nice and good car , would not think twice of driving it across country , just got done installing a OEM Battery , Tie rods , wheel alignment , it ready to go !!
Except for the heat would not want to get in a traffic jam at 20* degrees for any legth of time .

All work was performed by VW and parts were OEM VW over a few years 

The only way I would be able to tell is take the new pump out and measure the inpeller again the original inpeller which I have but the cost of doing that would be on me again $$$$ !!!


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## RalleyRabbit (Dec 11, 2011)

*no heat*

You more than likely only need to bleed the heater core thru the hole in the heater hose. I have to bleed mine if i loose an amount of coolant over time after i fill up the reservoir.


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