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Heater problems-warm on passenger side, cold on drivers side

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Heater problems-warm on passenger side, cold on drivers side

 
Old 12-19-2010, 01:56 PM
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Default Heater problems-warm on passenger side, cold on drivers side

Hi there guys, I hope someone can help.

I have a 2002 2.8 Quattro and I have no heat at all coming out of any of the driver's side vents either up, down or forwards.

The passenger side heats up a treat and on windscreen demist mode the passneger side clears nice and quickly, the driver's side slowly and with only cold air blowing out.

I have got no faults coming through from VAG-COM on the HVAC module and have vacuumed out the interior sensors to see if that had any bearing.

I have tried it on LO all the way through to HI with no success and have tried in re-circulation mode, econ mode and AUTO, but all with the same result a warm passenger and a cold driver.

I've searched the forum but have not been able to come up with a solution.....any ideas?

Many thanks
Phil
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Old 12-19-2010, 03:34 PM
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Not a diagnosis, but a couple things to consider:

Temperature in general is adjusted by the temperature control flap, not the amount of flow through a heater core, as in older cars. This flap must be operating in order to have heat adjustment to either side. There are other flap controls, of course, that adjust air routed side to side for separate driver/passengers temp controls.
That being said there are also 2 separate heater cores...passenger and driver. If driver's side was clogged or interrupted in some way, air routed through that side would theoretically be blowing through a cold core.

Questions: Has any "stop-leak" compound EVER been used in the engine coolant system?

Has the wrong coolant EVER been mixed with the required G-12 coolant?

If either of these has EVER happened, even draining and refilling would not necessarily clean out the residue left over or produced. Only a thorough chemical flush would correct it. The heater cores are the most susceptible to clogging from either of these mistakes.

Stop-leak is one of the worst things ever introduced to the automotive market and should only be used in dire emergency, followed by immediate repair and a chemical flush as soon as possible.

No matter what a label or advertiser says, there is nothing but certified G-12 coolant (pink, red or purple) that can be mixed with G-12 coolant. ANYTHING else, even in very small quantity, will create a thick corrosive sludge that will hide in heater cores and hose connections, causing clogging of core(s) and/or leaks at connections, unless thoroughly flushed chemically.
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Old 12-20-2010, 04:02 AM
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I guess I can never say never, but as far as I am aware this has only ever had the right coolant in it, and it has definitely never had any type of stop-leak compound added to the cooling system.

I had not noticed this becoming a gradual decline in the efficiency of the heating on the drivers side, but with the recent cold weather it has become very noticeable.

I will start off by trying to see if I can work out if the flap controls are correctly working, as a first instance. Is this anything that VAG-COM would help me with?

Thx
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Old 12-20-2010, 05:02 AM
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Vagcom...Yes, if you have access to it. I don't have it (just a code scanner), but Bentley manual has a whole section on diagnostic procedures for the climate control through the OBD2 system.
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Old 04-30-2019, 03:47 AM
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I have the same problem. But one more point - the red temp setpoint display on the driver's side is out, meaning I can only read the setpoint with the correct ambient lighting, to see the gray (not bright red) number. Wondering if some electrical connection in the unit opened and also took out some flap. Does the '97 have 2 heater cores?
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