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:
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.
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