Heater doesn't work on older Passat or A4

   #1  

Jef

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Starting to get these phone calls, so may as well put this up....

The problem as described by the customer:
No or low heat output. May work fine while driving, but very little heat when engine is at idle.

The reason:
Clogged heater core. This is a very common issue with the older Passat (3B) and A4 (8E). The heater core will get a build up of "mineral deposits" in it, this reduces the flow through the heater core, so there is a lot less surface area actively exchanging heat.

The solution:


The boring details:
  • Run full a full Auto-Scan.
  • Clamp off the 2 hoses going to the heater core and remove them.
  • Blow air through the heater core to empty it out as best you can.
  • Get 2 hoses to fit to the heater core and fill the heater core up with CLR.
  • Let soak for 2 hours or more.
  • Flush heater core out with garden hose.
  • If you think it needs it, do a second CLR soak, then garden hose flush.
  • Blow air through the heater core to empty it out as best you can.
  • Fill heater core with 50/50 coolant (G12 or G12 Plus).
  • Secure heater hoses back to heater core.
  • ???
  • Profit.
 
Last edited:
   #2  

Uwe

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I like it! The equivalent of EZ-OFF for heater cores! :cool:

-Uwe-
 
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