Question about 2001 Volkswagen Passat
My 2001 Passat's heater output is sluggish. The fan works and there is a bit of heat, but not the blast of hot air it used to make. Is this likely a thermostat issue? Is it a simple fix I can do?
There are known problems with this vehicle's heater core not getting enough coolant flowing through it to blow hot air.
1) Even if the coolant looks good, there are problems with the heater core plugging up. One solution is to use a heavy duty cleaner (CLR pipe cleaner) to back flush the heater core. To know if the heater core is plugged up, disconnect the 2 heater hoses at the heater core and somehow connect a hose to one end of the core. Try to flow water through, it doesn't have to be high pressure, and there should be a steady stream. If not, try to get the cleaner directly into the heater core and let it soak. Then back flush it and a lot of scale should be seen coming out.
2) The other problem is that since the heater core is the highest point in the cooling system air tends to get trapped in it. This should only happen if the coolant goes low or someone has opened the system to service it. There are a number of ways to bleed the system (vacuum bleed, pressure bleed). One of the hoses should have a small hole in it for bleeding air, pull that hose back just enough so the hole allows coolant to flow out of it. Then accelerate the engine and get a good flow coming out, when no more air bubbles are present, there should be good heat.
3)I've heard of bad water pumps with low flow causing issues as well as an aux. water pump not fuctioning correctly leading to poor heat output from the heater core. Someone should confirm this as I cannot get much information on the aux water pump(electronic pump by the alternator that is supposed to run after the car is shut off).
Hope this helps.
Posted on Jan 06, 2009
I live in Chicago, ilI and have the heater core same problem on passat 2003 GLX w 50K miles. Mechanic at general shop (not at VW dealer) flushed the heater core and heat is back and realy good as new. I like to do it myself but it is too cold to do outside or event in the garage.
Posted on Dec 12, 2010
Had the same problem with our passat after we replaced the coolant tank and an oil leak. We brought it back to the mechanic who then flushed the heating coil a few times. This slightly improved the situation. That week I was reminded/guilted by the label on the gas door that i really should be using 91 octane gas at the minimum, so I filled up with premium gas. After about 10 miles of driving the heat started working again. Probably a huge coincidence, but that is the only change i can think of. Read somewhere about heat build up in the engine when using lower octanes.. maybe that was confusing the thermostat?
Posted on Jan 16, 2010
Good luck folks I'm on my second heater core and VW refuses to admit a problem. 2002 GLS V6. $1700.00 at my dealer.. I owned a VW Fox same issue, bought new and 31,000 miles the Heater core failed, fogged the windsheild with antifreeze just like my golf and now my Passet has twice.They only last 30-36,000 miles so never buy a used VW with in that range unless you want to spend the money to replace the heater core. The heater core was recalled on the Golf because it's a big seller for VW. I will never buy a VW again.
Posted on Dec 15, 2010
Flush the heater core with normal tap water water pressure. If you use solvents it is very likely to cause leaks. There is a bleed hole on top of the p/s heater hose that should bleed air out of system, I usually will take the coolant bottle loose and hold it higher than the heater hoses when filling to achieve gravity bleed. Feathering the throttle will usually make a rushing noise in dash if there is a large air pocket, If normal flushing doesn't work you need a new heater core if air box flaps are working normally.
Posted on Feb 03, 2015
2001 1.8 passat here what i did with drove car till warm park shut off unhook upper radatior hose where that hose conect to metal one careful hot let fluid run out hooked waterhose to radatior hose flush till run clear then hook to metalone and flush till run clear then on hook hoses at heater core 2 then to to waterhose and flush till clear now to heater core go to auto parts store get 3 foot of heater hose or any hose to fit on heater core hook water hose to it and backflush till run clear then other side of heater core same till clear then i got air compresser out and hooked it toheater core use ing the 3 foot hose and aplastic bag toseal it blow water out easy try toblow all water out then poor CLR CLEANER in through 3foot hose till it come out other side of core let stand half hour blow out with compresser then water do this 3 times only use CLR in haeter core then rinse till clear iused air compresser to blow water out of motor and to raditor make sure i could 1 gal anti freeze backin now resemble check engine light came on after idid all this went out 2 day later could of went to autozone they would of ran free scan ask to reset MY HEAT IS GREAT NOW
Posted on Dec 24, 2009
Were is temp gauge at? should be in the middle of gauge if not RR stat.make sure the cabin filter is good or youll get no air flow
Posted on Nov 30, 2008
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