Disabling heater core

[skyblue]

I've been thinking about installing a tap so I can turn off coolant going to the heater core in summer so that the fan doesn't pick up any heat from it, despite the air door blocking it off I still feel as though it warms the air up, this is especially evident when I open the window a bit and the air is far cooler, despite the temp switch being as far over to the blue side as possible. I don't use A/C because I'm stingy with fuel.

I'm wondering if anyone else has fiddled with this, I'm concerned if I block off the heater core for an extended period that the fluid might go "off", I've heard that some people have had jelly in their heater cores and because the fluid would be stationary for so long due to the tap that it may solidify slightly.

The other thing I was thinking of was just disconnecting the heater core, draining as much as possible and joining the two hoses together and then plugging off the core so insects don't go living in there.

[Top_Fuel]

...despite the air door blocking it off I still feel as though it warms the air up...

You might want to check out this thread:

Heater off and it heats the car!

[skyblue]

You might want to check out this thread:

Heater off and it heats the car!

Thanks very much, should have known it was already here, I just checked my air flap and it shuts hard up against the heater portion but I think I'll have to bypass the core, because it's still heating it up somehow.

[mohammad]

I just wanted to point some things out

1. this may slightly increase short trip fuel economy as the heater core removed is just 1 less thing that the coolant needs to warm up. the heat exchanger is a decent amount of thermal mass

2. The PTC controller has a thermal probe mounted on top of the heater core, so even without the heater core being connected the electric PTC element will probably still be functional and provide you with some heat which would be helpful when trying to defog windows.

[skyblue]

I just wanted to point some things out

1. this may slightly increase short trip fuel economy as the heater core removed is just 1 less thing that the coolant needs to warm up. the heat exchanger is a decent amount of thermal mass

2. The PTC controller has a thermal probe mounted on top of the heater core, so even without the heater core being connected the electric PTC element will probably still be functional and provide you with some heat which would be helpful when trying to defog windows.

Thank you, I'm still trying to decide if bypassing the core is worth it, I'm a bit worried about leaving whatever remained in the heater core for half a year, maybe it would go funny and cause problems when reconnected, I don't imagine I'd be able to get all the coolant out, maybe I could flush it out with water, but I'm not that keen on leaving water in there either.

[mohammad]

Thank you, I'm still trying to decide if bypassing the core is worth it, I'm a bit worried about leaving whatever remained in the heater core for half a year, maybe it would go funny and cause problems when reconnected, I don't imagine I'd be able to get all the coolant out, maybe I could flush it out with water, but I'm not that keen on leaving water in there either.

Im not sure why you think automotive coolant would go bad if left stationary. If you went with a mixer valve like this one on EBAY then you could maybe reduce the flow significantly without completely stopping the flow of coolant to the heater core. Alternatively it would make it easy for you to occasionally cycle the heater on/off to move coolant around.


I would also like to point out that a lot of automobiles already use coolant flow control valves to control heat instead of trying to direct air around the heater core. So it’s likely the coolant issues you are concerned about have already been proven false.

[klroger]

I think Mohammad's idea is perfect for what you want. Run a control cable into the dash & you wouldn't even need to open the hood to turn it on or off!!!

[foama]

Just to mention it:
If you block the coolant flow through the heater core, make sure the coolant flow can bypass it! You could use a "U" pipe instead of the core. Remember the coolant flowing through the heater core also flows through other stuff, you don't want to kill that flow.

[mohammad]

Just to mention it:
If you block the coolant flow through the heater core, make sure the coolant flow can bypass it! You could use a "U" pipe instead of the core. Remember the coolant flowing through the heater core also flows through other stuff, you don't want to kill that flow.

you are correct foma, the product i linked does bypass the core with a "u pipe" when the heater core is shutoff thats why it has 4 connections.

I was wondering how the coolant gets to the heater core and where it comes from. I dont really see anything in the FSM, Other than the literal location of the hoses. I mean the flow within the engine block.

[foama]

I was wondering how the coolant gets to the heater core and where it comes from. I dont really see anything in the FSM, Other than the literal location of the hoses. I mean the flow within the engine block.

The coolant flows from the cylinder head where coolant gets hottest, then through the heater core, the throttle flap, and goes to the bottom of the block where it slowly recirculates within the block towards the cylinder head. The thermostat and radiator is being bypassed by this flow, but it is absolutely necessary for the coolant to actually flow within the block especially with a cold engine. Without that flow during warm-up, the cylinder head would overheat while the thermostat which is located in the lower block(!) remains cold.
Btw: The coolant and engine oil have large-surface passages right next to each other inside the lower block which are in effect a very effective oil/water heat exchanger! Thats why the oil temperature at high speed on the highway will not exceed coolant temperature, and also why the oil warms up comparatively fast during warm-up.