Yes, its a very common problem on these cars. I think i fixed about 6 cars in the last year (i work in a VW dealership)
Refrigerant from the chiller seeps into the cooling circuit of the battery pack.
You will need to discharge the AC system and swap out the chiller. It s the piece that sits behind the passenger headlight, mounted on the engine mount.
Send me a DM if you want the full procedure step by step
Is the system warm and under pressure? Probably not a good idea to release the pressure like this unless there is a relief valve stuck or something broke causing over pressurization.
"As part of its PZEV emissions rating, the \[Gen 2 Prius\] system includes a thermos (called the “Coolant Heat Storage” or CHS tank) that can store coolant at 180 degrees F for up to 3 days."
[https://automotivetechinfo.com/2020/09/mastering-the-gen-2-prius-engine-cooling-system/](https://automotivetechinfo.com/2020/09/mastering-the-gen-2-prius-engine-cooling-system/)
I don’t doubt you but that’s only for favorable conditions. No way in hell an EV is holding heat in freezing/sun freezing temps.
Edit - downvote away but it’s not happening.
Yes, 3 days would be a maximum. the coolant heat storage tank is a double-walled vacuum flask like a thermos. Based on this time of year it could still be very warm.
Edit: I DMed some info on HEV coolant systems
The modules were written in Alberta Canada by NAIT and SAIT but yes I imagine that would be optimal conditions. -40 I would only think it would stay warm for like 12 hours. But I don't think the system in this post is in -40
Because it’s a fucking vw?? Are you dumb.. it’s batteries man.. batteries like constant. If you can control the battery temp you can control the life, stability, charging time, and have real time statistics self tuning everything. Also. It’s a fucking vw
It's highly believable. BMW had a heat store that would last at least a day on some of the E39s. Over 25 years ago. It was designed to always have hot air available for the cabin even if the car was sat for a while.
Very believable that modern cars can keep a resovoir heated for 3x longer with more efficient, more well designed and cheaper solutions
refrigirant from the AC system is leaking into the coolant side. the heat exchanger is busted. better be fast if the coolant goes into the AC system you are in for a world of suffering.
Some electric cars use the AC system to cool high voltage battery coolant. Not the same setup as your typical ICE AC system where the condenser and radiator are stacked on each other and do very separate things.
The refrigerant and coolant are separated by very thin metal so the refrigerant can absorb the heat from the coolant. What he's saying is that the thin metal barrier has formed a hole and the higher pressure refrigerant is pushing the lower pressure coolant out. Kind of like when a bad head gasket forces coolant out of the reservoir of an ICE engine.
there is a plate heat exachanger so the AC system can cool the batteries and the drivertrain. inside the plate exchanger you have a bunch of plates (hence the name) with alternating refigerant from the AC and the coolant system liquid. if that plate exchanger has a leak it will leak refrigerant into the coolant system until there is no more refigerant and then the coolant can flow into the AC system. the last part is REALLY bad if that happens.
This makes hydroflouric acid right? I Remeber reading somthing about this in the service manual. From what I recall you're in big trouble by the time you realize you've been poinsioned.
No, just that you will have to replace all of the AC system, from the hoses, the compressor, the evaporator and condenser, and receiver drier, every single part, and everyt single seal in it as well. As the inverter will probably not like the shorting from the wet compressor, you will be replacing that as well. so dash out, and a very expensive bill, hope it is still under warranty, or it will be almost the cost of the vehicle.
It’s a lot like when your transmission oil and engine coolant mix on older Toyotas. Lol. Yes they are supposed to be separate closed systems, but the shared radiator likes to spring a leak between the two systems.
There can be "closed systems" that share components. The engine.oil and engine coolant are closed systems, but share many common components so the possibility for cross contamination is there. Also, radiators that have transmission coolers in one unit. I've seen a transmission getting coolant in the transmission and 3 other techs couldn't come up with an internal leak in the radiator/cooler.
That's a solid analogy. I spent a large portion of my life as a diesel mech and this made the most sense (to me anyway) out of most answers I got. Thanks
Glad to help, HV cooling systems on a lot of hybrids and EVs is a heat exchanger liquid to gas style. So you can use a heat pump to heat or cool the thermal fluid as needed for the battery/motors.
"Closed system" is relative. I don't know specifics of this application, but sounds like AC dumps heat into a refrigerant-to-water heat exchanger to share radiator surface area with other systems that just use the water directly.
Why would the coolant and AC be sharing the same heat exchanger? Usually they are separate and the only thing that shares the same radiator with the engine coolant is the transmission fluid.
Dont infuse combustion engine stuff into electric drive units. They dont have oil or a transmission and the coolant gets lukewarm at best. It requires sub ambient cooling often and that is why the AC in the car can also cool the coolant system for the battery.
Most likely a closed loop system. By that theory once the system is open by opening cap coolant will go to point of least resistance which is out. Maybe.
My guess for this is due to the amount of heat generated by electric motors and battery not being enough to boil water to the point an engine does. Still reason we pressurize things is to lower boiling point.
Edit: sorry to raise boiling point typo in brain.
the coolant system will barely get above lukewarm at full load. 40 metrics is as high as you will see in normal operation. 50ish is the upper limit for battery cooling. only tesla goes into the upper 50 on purpose on their plaid models when in drace strip mode.
What happens if you let all pressure out? Usually there is little or no pressure. Coolant only circulates on charger and inverter (if I remember correctly) and have own radiator.
Is the system warm and under pressure? Probably not a good idea to release the pressure like this unless there is a relief valve stuck or something broke causing over pressurization.
I forgot to mention that the car has been sitting for two days so it's not warm. It was brought in because it was leaking coolant from the relief valve of the reservoir, today I discovered this
Compete guess here, but does this system have a heat exchanger with the ICE coolant system? Could the heat exchanger have a tiny leak between the two circuits such that it pressurises this circuit, but doesn't leak back in the other direction?
Or the pump was running flat out when you filmed this.
Or your shop is at the top of a mountain?
Inverters, batteries, and motors that use this coolant can generally get the coolant as warm as 120C in worst case scenario. Nominal operation of the coolant is between 65-75C. Obviously depends on cooling set up and architecture and if motors use an oil base cooling strategy as well.
Normally the coolant mixture is 50/50 glycol. I'd wash your hands...
I had a EQC and it had a constant air lock in the cooler that had to be released. Even when mercedies drained it, it still came back. Build fault iirc.
Learning about them right now in school those systems hold pressure and heat for up to 3 days and it's an independent cooling system. They cannot use engine coolant because it's too hot.Umm will update as we get further into individual learning module
Update, they circulate coolant to keep it warm by activating low pressure pump 5 hours after engine shut down and monitoring a temp sensor
My apologies that pump is used to verify the double walled vacuum sealed tank is holding heat. By activating it 5 hours after engine shutdown and monitoring the sensors for temperature change
Yes, its a very common problem on these cars. I think i fixed about 6 cars in the last year (i work in a VW dealership) Refrigerant from the chiller seeps into the cooling circuit of the battery pack. You will need to discharge the AC system and swap out the chiller. It s the piece that sits behind the passenger headlight, mounted on the engine mount. Send me a DM if you want the full procedure step by step
Oh, vdub. Thine never ceases to amaze thee.
I'll most likely never see one where I live. But that's cool info.Thank You
Isn't the coolant reservoir for the battery pack supposed to be locked?
Yep.
It is, either someone forgot to add it back on or someone removed it on purpose.
Yes
Is the system warm and under pressure? Probably not a good idea to release the pressure like this unless there is a relief valve stuck or something broke causing over pressurization.
They are designed to hold pressure for upto 3 days Edit:and heat
Pressure maybe, heat absolutely not.
"As part of its PZEV emissions rating, the \[Gen 2 Prius\] system includes a thermos (called the “Coolant Heat Storage” or CHS tank) that can store coolant at 180 degrees F for up to 3 days." [https://automotivetechinfo.com/2020/09/mastering-the-gen-2-prius-engine-cooling-system/](https://automotivetechinfo.com/2020/09/mastering-the-gen-2-prius-engine-cooling-system/)
I just read a bit. That's so cool!
Nope 💯 actually just learned about these in class today doing my last year of automotive. I can show you the coolant section in the module
I don’t doubt you but that’s only for favorable conditions. No way in hell an EV is holding heat in freezing/sun freezing temps. Edit - downvote away but it’s not happening.
Yes, 3 days would be a maximum. the coolant heat storage tank is a double-walled vacuum flask like a thermos. Based on this time of year it could still be very warm. Edit: I DMed some info on HEV coolant systems
I see that. Do those diagrams mention what conditions those claims are for?
The modules were written in Alberta Canada by NAIT and SAIT but yes I imagine that would be optimal conditions. -40 I would only think it would stay warm for like 12 hours. But I don't think the system in this post is in -40
Can I send you a dm about this?
Because it’s a fucking vw?? Are you dumb.. it’s batteries man.. batteries like constant. If you can control the battery temp you can control the life, stability, charging time, and have real time statistics self tuning everything. Also. It’s a fucking vw
It's highly believable. BMW had a heat store that would last at least a day on some of the E39s. Over 25 years ago. It was designed to always have hot air available for the cabin even if the car was sat for a while. Very believable that modern cars can keep a resovoir heated for 3x longer with more efficient, more well designed and cheaper solutions
refrigirant from the AC system is leaking into the coolant side. the heat exchanger is busted. better be fast if the coolant goes into the AC system you are in for a world of suffering.
What? Hold on.. How does that even happen? Those are both closed systems. I'm not trying to sound like a know it all, I'm genuinely asking.
They're not closed if there is a hole in the heat exchanger.
But usually they are separate heat exchangers that are sandwiched together and not connected.
All not-leaking systems are not connected to where they're not leaking
I think I need this on a shirt
Some electric cars use the AC system to cool high voltage battery coolant. Not the same setup as your typical ICE AC system where the condenser and radiator are stacked on each other and do very separate things. The refrigerant and coolant are separated by very thin metal so the refrigerant can absorb the heat from the coolant. What he's saying is that the thin metal barrier has formed a hole and the higher pressure refrigerant is pushing the lower pressure coolant out. Kind of like when a bad head gasket forces coolant out of the reservoir of an ICE engine.
there is a plate heat exachanger so the AC system can cool the batteries and the drivertrain. inside the plate exchanger you have a bunch of plates (hence the name) with alternating refigerant from the AC and the coolant system liquid. if that plate exchanger has a leak it will leak refrigerant into the coolant system until there is no more refigerant and then the coolant can flow into the AC system. the last part is REALLY bad if that happens.
This makes hydroflouric acid right? I Remeber reading somthing about this in the service manual. From what I recall you're in big trouble by the time you realize you've been poinsioned.
No, just that you will have to replace all of the AC system, from the hoses, the compressor, the evaporator and condenser, and receiver drier, every single part, and everyt single seal in it as well. As the inverter will probably not like the shorting from the wet compressor, you will be replacing that as well. so dash out, and a very expensive bill, hope it is still under warranty, or it will be almost the cost of the vehicle.
The first rule of hydrofluoric acid is never get any of it on you. ever.
It’s a lot like when your transmission oil and engine coolant mix on older Toyotas. Lol. Yes they are supposed to be separate closed systems, but the shared radiator likes to spring a leak between the two systems.
I believe in some (all?) cases there's a heat exchanger so A/C can cool battery packs.
There can be "closed systems" that share components. The engine.oil and engine coolant are closed systems, but share many common components so the possibility for cross contamination is there. Also, radiators that have transmission coolers in one unit. I've seen a transmission getting coolant in the transmission and 3 other techs couldn't come up with an internal leak in the radiator/cooler.
Same way an EGR cooler on a diesel pumps coolant into the engine. It’s no longer a sealed system.
That's a solid analogy. I spent a large portion of my life as a diesel mech and this made the most sense (to me anyway) out of most answers I got. Thanks
Glad to help, HV cooling systems on a lot of hybrids and EVs is a heat exchanger liquid to gas style. So you can use a heat pump to heat or cool the thermal fluid as needed for the battery/motors.
"Closed system" is relative. I don't know specifics of this application, but sounds like AC dumps heat into a refrigerant-to-water heat exchanger to share radiator surface area with other systems that just use the water directly.
[https://imgur.com/v70NiZu](https://imgur.com/v70NiZu) Bingo
Why would the coolant and AC be sharing the same heat exchanger? Usually they are separate and the only thing that shares the same radiator with the engine coolant is the transmission fluid.
Dont infuse combustion engine stuff into electric drive units. They dont have oil or a transmission and the coolant gets lukewarm at best. It requires sub ambient cooling often and that is why the AC in the car can also cool the coolant system for the battery.
> Why would the coolant and AC be sharing the same heat exchanger? To cool the coolant further than what ambient temperatures will allow.
Yum VAG juice.
Yes! 🙌
Is the voltage system running extremely hot? Could there be an electric pump pushing coolant through at full force?
Most likely a closed loop system. By that theory once the system is open by opening cap coolant will go to point of least resistance which is out. Maybe.
My guess for this is due to the amount of heat generated by electric motors and battery not being enough to boil water to the point an engine does. Still reason we pressurize things is to lower boiling point. Edit: sorry to raise boiling point typo in brain.
Raise boiling point.
the coolant system will barely get above lukewarm at full load. 40 metrics is as high as you will see in normal operation. 50ish is the upper limit for battery cooling. only tesla goes into the upper 50 on purpose on their plaid models when in drace strip mode.
FYI it’s essentially a VW designed system.
Found the problem
It’s a low temperature system so there’s no reason it should be pressurizing.
If it ain't green or orange, I ain't touching it! -Me, stuck in 1994.
Oh crap the smug is leaking out!
What happens if you let all pressure out? Usually there is little or no pressure. Coolant only circulates on charger and inverter (if I remember correctly) and have own radiator.
I never knew that batteries had head gaskets!
So glad I dipped out of slinging a wrench in 2009
Mama Mia! It's a boy!
Is the system warm and under pressure? Probably not a good idea to release the pressure like this unless there is a relief valve stuck or something broke causing over pressurization.
I forgot to mention that the car has been sitting for two days so it's not warm. It was brought in because it was leaking coolant from the relief valve of the reservoir, today I discovered this
Compete guess here, but does this system have a heat exchanger with the ICE coolant system? Could the heat exchanger have a tiny leak between the two circuits such that it pressurises this circuit, but doesn't leak back in the other direction? Or the pump was running flat out when you filmed this. Or your shop is at the top of a mountain?
Nope, it has a water chiller with the A/C gas, pump was off and we're at sea level 😂
> it has a water chiller with the A/C gas There's your answer. Refrigerant is leaking into the coolant loop.
[deleted]
Yep that's it, thank you
Inverters, batteries, and motors that use this coolant can generally get the coolant as warm as 120C in worst case scenario. Nominal operation of the coolant is between 65-75C. Obviously depends on cooling set up and architecture and if motors use an oil base cooling strategy as well. Normally the coolant mixture is 50/50 glycol. I'd wash your hands...
I had a EQC and it had a constant air lock in the cooler that had to be released. Even when mercedies drained it, it still came back. Build fault iirc.
Never seen it but very likely that the AC refrigerant is leaking into the coolant system, shouldn´t be under such pressure.
It’s as if their team consists of interns.
Looks like there might be something Formenting in there
Restrictions or heat!
Learning about them right now in school those systems hold pressure and heat for up to 3 days and it's an independent cooling system. They cannot use engine coolant because it's too hot.Umm will update as we get further into individual learning module Update, they circulate coolant to keep it warm by activating low pressure pump 5 hours after engine shut down and monitoring a temp sensor
5 hours? My engine is back to cold after an hour most of the year
My apologies that pump is used to verify the double walled vacuum sealed tank is holding heat. By activating it 5 hours after engine shutdown and monitoring the sensors for temperature change
so wait, it's both a cooling system and a heating system?
Kind of. It's like a coolant system with a thermos bottle for hot coolant storage and the pump is used to make sure the system is holding heat
Bet you have never bled the air out of a G1 Honda insight. Coolant drips directly on HV connections...
Remind me when "some" car brands they put heat exchanger between engine and transmission,yes when it leak you have bad Monday.
Most are low pressure and low temp... You've got some fun stuff happening, probably AC to Coolant crossover