Does coolant flow through the heater core all the time?
- Thread starter The motor guy
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My Audi has 3 zone heat and air, driver, passenger and rear seat. There is a coolant pump that regulates whether coolant is flowing through the heater core. I know this first hand as one of the coolant pumps was making a bit of a racket recently and I caught the noise on my phone and showed it to the service advisor and he brought the shop foreman up and he said yeah the coolant pumps need replacing. I asked the shop foreman why he said pumps as in plural and he said that there were 2 stacked on top of each orher and he was going to replace them both. (Warranty repair so I said ok)
Pumps were ordered and then came in and I went up today to have them installed. 2 hours later service advisor said I was done and gave me the keys and off I go. About 20 miles from dealership I notice I'm cold so I crank the temperature knob from 72 to 80 and no change so I turn around. Long long story short the pump connected to the heater core controls is plumbed into the transmission cooler and the transmission cooler pump is connected to the lines running to the heater core.
Pumps were ordered and then came in and I went up today to have them installed. 2 hours later service advisor said I was done and gave me the keys and off I go. About 20 miles from dealership I notice I'm cold so I crank the temperature knob from 72 to 80 and no change so I turn around. Long long story short the pump connected to the heater core controls is plumbed into the transmission cooler and the transmission cooler pump is connected to the lines running to the heater core.
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I havent noticed any valves from what I remember looking at the firewall. Just hoses coming out of the cylinder head.l so I guess not. One less thing to fail I guess.
Originally Posted by motor_oil_madman
I havent noticed any valves from what I remember looking at the firewall. Just hoses coming out of the cylinder head.l so I guess not. One less thing to fail I guess.
Where there is no heat control valve there will be a blend door buried behind the dash. A valve is much easier to access and repair than the blend door but more likely to fail than the blend door..
I havent noticed any valves from what I remember looking at the firewall. Just hoses coming out of the cylinder head.l so I guess not. One less thing to fail I guess.
Where there is no heat control valve there will be a blend door buried behind the dash. A valve is much easier to access and repair than the blend door but more likely to fail than the blend door..
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Originally Posted by StevieC
Depends on the vehicle. Some have vacuum actuated valves to close off the coolant flow, some use electronic valves, some leave it flowing through the core all the time. It can also depend on whether the vehicle has dual / tri climate zones or not. There is no standard answer that fits all vehicles.
That said I'm a fan of it flowing through the core all the time. IMO these systems don't plug up the heater cores as often where the coolant it shut down through the core, say all summer long sort of thing.
Why would sitting cause the core in a well maintained system to clog? My winter car should be well clogged by now as it sits April though Nov for years and its its fine.
Heater core erosion from high flow rates is a real and much bigger issue, some manufacturers even install flow restrictions at the factory to help prevent this.
They can help prevent a huge labor job as the vehicle ages as well as improve A/C performance. Some cars with auto systems may already have one either under the hood or on the unit under the dash.
I install them on lots of cars where the labor time is high to change the core plus an A/C recharge, its an old school part that can still has a lot of benefit.
Depends on the vehicle. Some have vacuum actuated valves to close off the coolant flow, some use electronic valves, some leave it flowing through the core all the time. It can also depend on whether the vehicle has dual / tri climate zones or not. There is no standard answer that fits all vehicles.
That said I'm a fan of it flowing through the core all the time. IMO these systems don't plug up the heater cores as often where the coolant it shut down through the core, say all summer long sort of thing.
Why would sitting cause the core in a well maintained system to clog? My winter car should be well clogged by now as it sits April though Nov for years and its its fine.
Heater core erosion from high flow rates is a real and much bigger issue, some manufacturers even install flow restrictions at the factory to help prevent this.
They can help prevent a huge labor job as the vehicle ages as well as improve A/C performance. Some cars with auto systems may already have one either under the hood or on the unit under the dash.
I install them on lots of cars where the labor time is high to change the core plus an A/C recharge, its an old school part that can still has a lot of benefit.
It does on my Camry.
Originally Posted by Trav
Originally Posted by StevieC
Depends on the vehicle. Some have vacuum actuated valves to close off the coolant flow, some use electronic valves, some leave it flowing through the core all the time. It can also depend on whether the vehicle has dual / tri climate zones or not. There is no standard answer that fits all vehicles.
That said I'm a fan of it flowing through the core all the time. IMO these systems don't plug up the heater cores as often where the coolant it shut down through the core, say all summer long sort of thing.
Why would sitting cause the core in a well maintained system to clog? My winter car should be well clogged by now as it sits April though Nov for years and its its fine.
Heater core erosion from high flow rates is a real and much bigger issue, some manufacturers even install flow restrictions at the factory to help prevent this.
They can help prevent a huge labor job as the vehicle ages as well as improve A/C performance. Some cars with auto systems may already have one either under the hood or on the unit under the dash.
I install them on lots of cars where the labor time is high to change the core plus an A/C recharge, its an old school part that can still has a lot of benefit.
I would love to install one on my Rams for this very reason. The coolant heat and pressure at the back of the ISB cylinder head has proven to be enough to blow a freeze plug right out of the head under normal use. The heater core can't be too happy with this. I have my coolant filter plumbed to this part of the head's coolant gallery and found the filter's plastic restrictors blown in half.
Coolant from this part of the engine is sent directly into the heater core, and then into the turbo. The turbo makes turning off this circuit a really bad idea. It is possible to use another hole to direct coolant to the turbo separately, but I worry doing this would reduce flow to both.
But almost 400k one one, and over 400k on the other with no issue, so maybe not that big of a deal.
Originally Posted by StevieC
Depends on the vehicle. Some have vacuum actuated valves to close off the coolant flow, some use electronic valves, some leave it flowing through the core all the time. It can also depend on whether the vehicle has dual / tri climate zones or not. There is no standard answer that fits all vehicles.
That said I'm a fan of it flowing through the core all the time. IMO these systems don't plug up the heater cores as often where the coolant it shut down through the core, say all summer long sort of thing.
Why would sitting cause the core in a well maintained system to clog? My winter car should be well clogged by now as it sits April though Nov for years and its its fine.
Heater core erosion from high flow rates is a real and much bigger issue, some manufacturers even install flow restrictions at the factory to help prevent this.
They can help prevent a huge labor job as the vehicle ages as well as improve A/C performance. Some cars with auto systems may already have one either under the hood or on the unit under the dash.
I install them on lots of cars where the labor time is high to change the core plus an A/C recharge, its an old school part that can still has a lot of benefit.
I would love to install one on my Rams for this very reason. The coolant heat and pressure at the back of the ISB cylinder head has proven to be enough to blow a freeze plug right out of the head under normal use. The heater core can't be too happy with this. I have my coolant filter plumbed to this part of the head's coolant gallery and found the filter's plastic restrictors blown in half.
Coolant from this part of the engine is sent directly into the heater core, and then into the turbo. The turbo makes turning off this circuit a really bad idea. It is possible to use another hole to direct coolant to the turbo separately, but I worry doing this would reduce flow to both.
But almost 400k one one, and over 400k on the other with no issue, so maybe not that big of a deal.
Originally Posted by meep
my 06 tundra had a valve to cut off coolant to the core. aside from the '57 chevy we had years ago, the rest of our vehicles relied on blend doors.
It used to be customary for heater output air temperature to be controlled by a manually adjustable restricting valve in the coolant line. That's the method used by the two earliest cars in my signature. Temperature is much easier to control with modern blend-door systems, but it's still good to have a valve to shut off the flow, to minimize unwanted heat leakage in warm weather.
my 06 tundra had a valve to cut off coolant to the core. aside from the '57 chevy we had years ago, the rest of our vehicles relied on blend doors.
It used to be customary for heater output air temperature to be controlled by a manually adjustable restricting valve in the coolant line. That's the method used by the two earliest cars in my signature. Temperature is much easier to control with modern blend-door systems, but it's still good to have a valve to shut off the flow, to minimize unwanted heat leakage in warm weather.
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