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Discussion Starter #1
Hi LT,

I just relocated to a place where I will never use the heater, but will use AC daily. I have read through the massive Tony Wa thread and have added that project to the top of my list. That said, I need better AC, like tomorrow. Is there a quicker, easier way to bypass the heater core that won't permanently disable my engine until I have the time to do things properly?

I'm thinking of something like physically unplugging the pump or pulling a fuse somewhere? I saw another member installed a ball valve, and thats the principle I'm going for, at least temporarily. I am considering doing that, but I don't want to cut any pipes if I can avoid it.

1264482
 

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Tony Wa's solution is complicated because of "heat soak" cooling. I'm not sure where the name comes from but my understanding is: the heater core is used to help cool the engine once it is turned off. I have been running Tony's solution for over 15 years and 60K miles.

I wouldn't rely on the ball valve solution unless you find alternative operational cool down.
 

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Discussion Starter #3
The situation you reference is for cooling the engine down from very high temperatures after the vehicle has been shut off - would electronically disabling the pump restrict flow through the heater core without causing an engine code?
 

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Since the heater core and the radiator (in the Elige) are both always active when the thermostat is open, blocking one should just redirect more flow to the other. I don't see how heat soak prevention will be hurt at all.

EDIT: But I would not use a ball valve. Do a true bypass so the heat soak circuit is not stalled when the thermostat is closed.
 

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The radiator is not in line with the heat soak pump, at least I don't think so. putting a ball valve would defeat the heat soak function
 

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I don't know if the heater hoses are more easily accessible in the Elise, but if you can reach to put in a ball valve, you can reach to put in this:

I detailed this install here
 

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The radiator is not in line with the heat soak pump, at least I don't think so. putting a ball valve would defeat the heat soak function
I'm trying to read the diagram in the service manual which is poorly drawn, so you may be right. Either way, I agree that the electrical bypass is minimally extra work for much better results and lower risk. I have a Tony Wa original and would go with a solenoid instead if I had to do it again, but still it is great to have
 

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The hardest part of doing the Tony Wa's solution is cutting the heater lines and getting the valve installed in the lines. The rest is very easy. Any solution you do, you're going to have to cut the lines, so just do the full thing.

I did it last summer and it does make a big difference in how well the A/C works.
 

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Discussion Starter #10
I would like to bypass in the engine bay for both easier access and to remove heat from the down the side sills and under the dash. My understanding is that the radiator is not in line with the heat soak pump, which is why I want to just disable that pump rather than cut into lines.

In this thread, @turbophil explains what I am trying to do is no problem, and that the heat soak operates completely internal to the engine, even when the heater matrix is bypassed.

In this post, @+TSRAGR explains the ball valve option he installed with photos.
 

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Ah, didn't see your image was in the engine bay. Might as well try it
 

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First, the amount of hot water travelling through the heater pipes is insignficant compared to the radiator hoses

Second form the shop manual:


In conditions of 'heat soak', after stopping a hot engine, the re-circulation pump is energised under engine
ECU control to pump coolant through the heater circuit and limit the potential for localised boiling within the
cylinder head.

It does not speak of moving coolant internally, and does not appear to.

As much respect as I have for Phil, as a customer, I always take advice from racers with a grain of salt. They are more likely to blow up an engine long before damage from localised boiling would be evident


If you are complaining about the efficacy of the AC, tell us what mods you have done already. The Tony Wa mod is important, but unlikely to be a game changer on its own
 

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Discussion Starter #13
I completed this bypass, and the engine hasn't blown up yet!
I cut the engine bay coolant pipe and added a ball valve. Cutting into a pipe knowing it was going to start spewing coolant was unnerving. Conveniently though, I spilled enough coolant to match a bottle of redline water wetter.

For obvious reasons, unplugging the coolant recirculation pump does nothing (since we've been discussing that it only comes on when the engine is off and at high temperatures). Under normal operation, the water pump must create enough of a pressure differential to drive the heater matrix flow as well, spinning the non-energized recirc pump.
 

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the water pump must create enough of a pressure differential to drive the heater matrix flow as well, spinning the non-energized recirc pump.
This tells me the rad and heater circuits are connected somewhere, and, unless there's a check valve or something like, it is reasonable to assume that the recirc pump will push water through the rad when the thermostat is open. Recirc doesn't have to move a lot of air either, it just has to keep it from sitting stagnant on a hot spot. I still advocate for doing it "correctly" if you find yourself bored for an hour, but it sounds like you should be okay
 

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Sorry for the slight thread hijack, but it's at least a bit relevant.

I don't know if the heater hoses are more easily accessible in the Elise, but if you can reach to put in a ball valve, you can reach to put in this:

I detailed this install here
Hi Exigegus, I've been doing a lot of reading about the various iterations of the heater bypass mod in recent days after the blend door/flap in my Exige started playing up - often leaving me with only warm air. I know that ultimately I need to replace the blend door actuator, but as I've already spent too many hours with the clam off this winter I really want to avoid doing it again soon, so looking for the bypass mod to do in the meantime.

I found some older posts from yourself suggesting that an 'all in one' kit was pretty much plug and play on the factory wiring and that you created some piggyback harnesses to match. Is this still a solution you're running today, happy with its performance etc?

I believe it was this kit you referenced which I can hopefully import to the UK: Electronic Bypass Heater Valve Includes: Wire Harness & Rotary Switch [50-1555] | eBay

Thanks in advance!
 

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Sorry for the slight thread hijack, but it's at least a bit relevant.



Hi Exigegus, I've been doing a lot of reading about the various iterations of the heater bypass mod in recent days after the blend door/flap in my Exige started playing up - often leaving me with only warm air. I know that ultimately I need to replace the blend door actuator, but as I've already spent too many hours with the clam off this winter I really want to avoid doing it again soon, so looking for the bypass mod to do in the meantime.

I found some older posts from yourself suggesting that an 'all in one' kit was pretty much plug and play on the factory wiring and that you created some piggyback harnesses to match. Is this still a solution you're running today, happy with its performance etc?

I believe it was this kit you referenced which I can hopefully import to the UK: Electronic Bypass Heater Valve Includes: Wire Harness & Rotary Switch [50-1555] | eBay

Thanks in advance!
That appears to be the same unit

It runs today without problems.
I bought compatible connectors and pins to make the Y harness and so it runs both the door and the valve. The stock blend knob replaces the pot in the kit the way I wired it, so there are no extra wires. FI you blend door is glitchy you may want to wire it differently to get what you want until you open it up again
 

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That appears to be the same unit

It runs today without problems.
I bought compatible connectors and pins to make the Y harness and so it runs both the door and the valve. The stock blend knob replaces the pot in the kit the way I wired it, so there are no extra wires. FI you blend door is glitchy you may want to wire it differently to get what you want until you open it up again
Cheers fella, my first job is to rule out potential "non actuator" issues such as wiring and potentiometer knob. Its pointless implementing your solution if my knob is faulty!

Mine seems to just randomly switch to heat position whilst driving, then will seemingly randomly move back to cold again. I believe the default position is warm, so I assume my resistance feed from the potentiometer is weak/loose or similar. If I do deem the actuator to be the problem, I'll unplug it and fix it in the cool position until I can bypass the matrix.

I don't suppose you have any part numbers etc for the connectors you bought to make the patch lead?
 

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I bought compatible connectors and pins to make the Y harness and so it runs both the door and the valve.
I don't suppose you have any part numbers etc for the connectors you bought to make the patch lead?
Just found them in your original post, along with some UK suppliers - result! I'm trying to make out your pinout from the photo but do you recall what colour does what in the Lotus loom? I'm hoping to set this all up on the bench as I've got a spare actuator on its way, so with a few buckets of water I should be able to simulate everything if I can figure out the wiring (by far my weak area!)

One last question (for now, hope you don't mind) is I assume from your pictures that you skipped on the addition of the vacuum switch to retain the Lotus heatsoak pump capabilities of the system? I assume that hasn't been a problem by now if so!
 

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I spent a little more money on the 2 way valve to yes, keep the stock system in place, as Lotus is not known for over engineering things, and to avoid new wiring into the car, as it is difficult to get to the heater controls from the rest of the car. I also had my thoughts on whether vacuum would be reliable in a forced induction car
 

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I spent a little more money on the 2 way valve to yes, keep the stock system in place, as Lotus is not known for over engineering things, and to avoid new wiring into the car, as it is difficult to get to the heater controls from the rest of the car. I also had my thoughts on whether vacuum would be reliable in a forced induction car
Ah OK so you DO retain the ability to disable the bypass with this setup? Does the 2 way valve default to the 'open' position when powered off or have you achieve it some other way? Sorry for all the questions, I just feel your solution is the slickest of the bypass mods so want to get it right!
 
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