No heat HVAC pump revisited 97 A8Q
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No heat HVAC pump revisited 97 A8Q
All,
I STFA and came up with <a href="https://forums.audiworld.com/a8/threads/23874.phtml#127953">this gem</a> that tells me how to diagnose why I'd have no heat. The bleeder valve going into the heater core shows plenty of coolant getting where it needs to. The "out" valve is dry.
So either I have blockage in my heater core or the pump itself is faulty/old/rusty? Right?
Time to visit the shop, I think.
I STFA and came up with <a href="https://forums.audiworld.com/a8/threads/23874.phtml#127953">this gem</a> that tells me how to diagnose why I'd have no heat. The bleeder valve going into the heater core shows plenty of coolant getting where it needs to. The "out" valve is dry.
So either I have blockage in my heater core or the pump itself is faulty/old/rusty? Right?
Time to visit the shop, I think.
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Joined: Oct 2000
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If the pump is broken (but not clogged) you should still get heat
The pump just helps out at low rpm and makes the engine-off heating possible.
There are left and right heater cores. It seems odd that both would clog, especially if the rest of the cooling system including the expansion tank look decent.
Did you really rev it to 4000 rpm during bleeding? Did the heat quit working after some servicing or coolant leak? The heater core is emphatically not self bleeding?
(And for others new to the thread, you're supposed to unplug the electric pump when draining the coolant and not plug it in again until the heater is bled and working. This was in a service bulletin but not the service manual.)
Tom
There are left and right heater cores. It seems odd that both would clog, especially if the rest of the cooling system including the expansion tank look decent.
Did you really rev it to 4000 rpm during bleeding? Did the heat quit working after some servicing or coolant leak? The heater core is emphatically not self bleeding?
(And for others new to the thread, you're supposed to unplug the electric pump when draining the coolant and not plug it in again until the heater is bled and working. This was in a service bulletin but not the service manual.)
Tom
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Even when I pull the fuse I have no heat. Sometimes, if the car has been running...
for a little while I leave the blower off. When I first turn the blower on for 10-15 seconds it's nice and hot, then ice cold again.
I did rev to 4k w/ the bleeders open. The "in" bleeder was still full but the "out" bleeder was dry.
I did rev to 4k w/ the bleeders open. The "in" bleeder was still full but the "out" bleeder was dry.
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Maybe pull a hose between the pump/valve unit and a heater core?
To see if it coolant gets past the pump/valve unit.
Unless something sludgy was in the coolant, it seems more likely that one piece (the pump) is clogged than two (both heater cores). But neither problem seems very common.
If you had heat on the passenger side, that would be different.
Tom
Unless something sludgy was in the coolant, it seems more likely that one piece (the pump) is clogged than two (both heater cores). But neither problem seems very common.
If you had heat on the passenger side, that would be different.
Tom
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