I need some help with my 99 A4 Quattro. Ok, I recently got my coolant flushed many times over again but I am still not getting HOT HOT heat....just warm at times. It seems that the Thermostat is working fine but fluctuates at times. Any idea what this could be? PLEASE HELP!
**The heat is set @ "HI" at all times but does not blow warm at all unless on the freeway....then a little warmer.
I absolutely agree with the backflush and bleeding the air in the heater core.
Couple of years ago, I had similar issues. The overflow tank looked brownish so there had to be some rust or gunk in the coolant system.
I took the two hoses off at the connection to the heater core near the firewall (between the battery and the brake vacuum booster. Just simply used a garden hose with a spray head (set it to "jet" or "stream") and then flushed the heater core. Be careful as the water may come back to hit you in the face or eyes. Spray water from the outlet hose(closest to the battery; one with a bleeder hole) and saw the rusty gunk come out of the inlet hose (closest to the brake vacuum booster).
Then check the flow by spraying the water from the inlet hose to make sure water was coming out clear. Refill with extra 50/50 coolant/water mixture in the overflow tank and check for correct level.
Have not had problem with heat in the car since.
1996 Audi A4Q, 12Valve 2.8LV6 (AFC)