21 plate C-HR condensation / freezes / frost inside cabin

[O.W.L.]

I can understand all that, the physics of the thing, but why did it not happen in all my other cars? OK, there was always a little condensation, but not cupfuls, and certainly not enough to freeze on the inside!

[GBgraham]

14 minutes ago, O.W.L. said:

I can understand all that, the physics of the thing, but why did it not happen in all my other cars? OK, there was always a little condensation, but not cupfuls, and certainly not enough to freeze on the inside!

It could be in the design with being too air tight or a fault where some flap in the ventilation system doesn't close and is letting cold damp air in. Not knowing the system I could say, only surmise.

Once the moisture is in there it will take some getting rid of at this time of year. Get two people to sit in the car on a cold night and just see how quickly it fogs up the windows.

BTW, Do you have cloth seats?

Look at all the problems people had in the fitting of double glazing along with central heating, condensation and even mould, because no fresh air moving about, just the same old stuff, especially in the bedrooms.

On a good drying day, if possible try and open the doors or/and windows and let some air circulate.

[forkingabout]

Make sure the vehicle isn't in ECO mode.

Make sure the climate control isn't set to ECO.

Make sure the air recirculation function is switched OFF ( button not lit! ) 

Make sure the A/C is switched ON ( button lit up )

Make sure the AUTO button is switched ON ( button lit up )

Set the temperature around 22 or 24 deg C

[GBgraham]

I have just found this if anyone want's to get technical

https://www.tochr.net/1794/system_description.html

[O.W.L.]

4 hours ago, forkingabout said:

Make sure the vehicle isn't in ECO mode.

Make sure the climate control isn't set to ECO.

Make sure the air recirculation function is switched OFF ( button not lit! ) 

Make sure the A/C is switched ON ( button lit up )

Make sure the AUTO button is switched ON ( button lit up )

Set the temperature around 22 or 24 deg C

Check to all of those. Still get unacceptable condensation

 

[O.W.L.]

4 hours ago, GBgraham said:

It could be in the design with being too air tight or a fault where some flap in the ventilation system doesn't close and is letting cold damp air in. Not knowing the system I could say, only surmise.

Once the moisture is in there it will take some getting rid of at this time of year. Get two people to sit in the car on a cold night and just see how quickly it fogs up the windows.

BTW, Do you have cloth seats?

Look at all the problems people had in the fitting of double glazing along with central heating, condensation and even mould, because no fresh air moving about, just the same old stuff, especially in the bedrooms.

On a good drying day, if possible try and open the doors or/and windows and let some air circulate.

Yes, I have the half leather/half cloth seats

[O.W.L.]

4 hours ago, GBgraham said:

I have just found this if anyone want's to get technical

https://www.tochr.net/1794/system_description.html

Blimey. I gave up halfway through that!

[TonyHSD]

1 hour ago, O.W.L. said:

Blimey. I gave up halfway through that!

That’s super interesting, although it does not point what could have cause your issues but it is nice to have first hand information how the things work. 
I guess it might be something wrong with one of these two: 

1. Fresh air parking control - in my car since I usually stay in long time I noticed that sometimes after I turn off the car flaps are moving inside the dashboard, something it’s opening or closing. 

2. Ion generator- here also in certain conditions I can sense a funny smell from the hvac , don’t know if my car has that option at all or it’s perhaps something else but if this is at fault in your case.  it might messed with the system. But not sure about it. 
 

[Cyker]

I think you need to find where the water is coming from, and/or somehow remove it. After my windscreen was replaced it had some major condensation until I wiped and soaked it all up with a cloth.

Leave the AC on all the time - That will help extract moisture from the cabin. Also maybe get a load of silica gel packs from electronics packaging, or buy one of those dehumidifier block things from Robert Dyas (They seem to sell them in supermarkets too now!)

When parked up, make sure the vents are on fresh air and not recirculated; I find if I leave it on recirc the car has a higher tendency to mist up, and also my car gets that nasty swampy smell when the fans start up.

I do wonder if the cabin isn't totally sealed and moist air is getting in; My Mk4 sounds like there's an opening somewhere, but I'm not sure if that's really the case or it's just the total lack of sound deadening making it sound like that  

[forkingabout]

I'm currently running 24 deg C with FAST switched on as below. 

No issues with condensation & very quick to demist.

[Jimota]

On 1/27/2023 at 10:51 PM, forkingabout said:

I'm currently running 24 deg C with FAST switched on as below. 

No issues with condensation & very quick to demist.

That sounds about right.

[O.W.L.]

My 2018 C-HR (purchased in December 21) never had a condensation problem until the winter of 22. Since then it has been quite dreadful but only when the outside temperatures drop to around 2 or 3 degrees or lower.

Marshalls Toyota in Canterbury have had it in for the last 2 days, but it hasn't manifested any moisture and they can find no reason for it. No damp carpets, boot seal OK, A/C drain tube OK etc etc. Unfortunately, the weather here has been fairly warm for the time of year, so no condensation for them to look at.

What they did say, which I'm happy with, was if and when the forecast is for temperatures of about freezing, I'm to phone them up and they will take it in straight away, for another look.

 

[GBgraham]

18 hours ago, O.W.L. said:

My 2018 C-HR (purchased in December 21) never had a condensation problem until the winter of 22. Since then it has been quite dreadful but only when the outside temperatures drop to around 2 or 3 degrees or lower.

Marshalls Toyota in Canterbury have had it in for the last 2 days, but it hasn't manifested any moisture and they can find no reason for it. No damp carpets, boot seal OK, A/C drain tube OK etc etc. Unfortunately, the weather here has been fairly warm for the time of year, so no condensation for them to look at.

What they did say, which I'm happy with, was if and when the forecast is for temperatures of about freezing, I'm to phone them up and they will take it in straight away, for another look.

 

It certainly is a mindbender but to apply the science there must be a dampness somewhere which is to be proved by the condensation.

Hope it is soon rectified for you, please keep in touch with the journey and outcome.

[O.W.L.]

Certainly will. It just doesn't make much sense to me. About 3 weeks ago, when it was quite dry and temps were hovering just above zero, I drove to a meeting in East Sussex. Screen was dry inside when I set off. The two others attending had similar length of journeys to get there. We all parked in a row.

The meeting lasted for around 3 hours, and when we came out, the other guys, driving a Porsche 911 and a Hyundai Tucson, got in and drove off. I had so much condensation that it took me about 10 minutes to mop it all off of the front windscreen, then another 10 to get the heater to dry it out enough to drive off. Very frustrating.

[GBgraham]

12 hours ago, O.W.L. said:

Certainly will. It just doesn't make much sense to me. About 3 weeks ago, when it was quite dry and temps were hovering just above zero, I drove to a meeting in East Sussex. Screen was dry inside when I set off. The two others attending had similar length of journeys to get there. We all parked in a row.

The meeting lasted for around 3 hours, and when we came out, the other guys, driving a Porsche 911 and a Hyundai Tucson, got in and drove off. I had so much condensation that it took me about 10 minutes to mop it all off of the front windscreen, then another 10 to get the heater to dry it out enough to drive off. Very frustrating.

May be one of these may give you an interesting indication of conditions   

https://www.ebay.co.uk/itm/394434555452?hash=item5bd621ae3c:g:FJEAAOSwjJRi--ad&amdata=enc%3AAQAHAAAAoCjZnCIsW2dWkCFB%2FpiekOlUZ071Ify3XYFzxhPfoUUTio5udjkady1fUe%2F8%2BpssaKXW4de7S5CylxVBgIDoz25fxmWM%2BLhaaF3GsCd5%2Fu0mqu2yS86%2F46j3N2E%2BsY9yH0B1Wy8%2FyjgAnpv5XWyk2QvMKH3ldQEc8TXQd%2F9T8oeeDqCJBYIFdZZhO8h6ltCcTyMlXbHi%2B8CCzAuQbM2FsqU%3D|tkp%3ABk9SR7bLgrnMYQ

[O.W.L.]

That'a a damn fine idea - thank you. I will get one of those & see what it can tell me. Might have to wait till we get more cold weather, but I'll be waiting!

[GBgraham]

44 minutes ago, O.W.L. said:

That'a a damn fine idea - thank you. I will get one of those & see what it can tell me. Might have to wait till we get more cold weather, but I'll be waiting!

Even if there is no cold weather it would be interesting to measure the outside humidity and compare with an inside cabin reading.

[O.W.L.]

I'll do that. Have ordered one - estimated 5 days for delivery.

[TonyHSD]

30 minutes ago, O.W.L. said:

I'll do that. Have ordered one - estimated 5 days for delivery.

Good, when you get that you can try to use the car with AC ON for few days and then with AC OFF for few days and measure the humidity.
I believe that AC during winter cause more issues than help and in many cases is the culprit for moisture locked into the cabin and the results with frozen or misted windscreen. Please note: 
The problem with AC happens not while it’s ON and working but after that when you turn off the car and leave it parked with hvac not running and all doors and windows shut.  👍

[GBgraham]

28 minutes ago, TonyHSD said:

Good, when you get that you can try to use the car with AC ON for few days and then with AC OFF for few days and measure the humidity.
I believe that AC during winter cause more issues than help and in many cases is the culprit for moisture locked into the cabin and the results with frozen or misted windscreen. Please note: 
The problem with AC happens not while it’s ON and working but after that when you turn off the car and leave it parked with hvac not running and all doors and windows shut.  👍

But isn't this why you should always use climate control to get the correct balance? A/C alone is just brute force cold air through the evaporator.

[TonyHSD]

5 hours ago, GBgraham said:

But isn't this why you should always use climate control to get the correct balance? A/C alone is just brute force cold air through the evaporator.

These cars hvac system always work in automated control as the name suggests auto climate control, however there are some settings that are vital for the proper work. The button auto when selected will automatically redirects the air flow between windscreen, feet, middle of the dash and also control different fan blower speeds. In addition to that will use AC as necessary, mostly all the time a bit to condition the air and make it dryer. Nothing wrong with that but the problem is during the cold freezing temperatures below 4C° the ac compressor won’t start although been selected ON or auto and after a while you had been driving the car the engine bay temperature will rise and the ac will kick in and usually that happens when you just about to arrive at your destination. What happens next is the AC evaporator becomes colder than before because the compressor has started and shortly after you turn the car off and here is the problem where it starts from. You turn off your car and walk away, but there is air coming inside the cabin that passes through ice cold ac evaporator and through hot heater core then straight into the cabin and particularly windscreen, this air stream brings a lots of moisture as a result of air passing through two bodies worth very large temperatures margins, one is very cold perhaps 4C° and the other is around 40-60C°. 
If your AC was switched off manually, your car hvac system either in manual or auto mode will not start your ac compression at all even after long drive, your cabin would be dry and aired by the heating only as in the older cars and you will have less moisture formed along the air ducts and windscreen. 

[GBgraham]

13 hours ago, TonyHSD said:

These cars hvac system always work in automated control as the name suggests auto climate control, however there are some settings that are vital for the proper work. The button auto when selected will automatically redirects the air flow between windscreen, feet, middle of the dash and also control different fan blower speeds. In addition to that will use AC as necessary, mostly all the time a bit to condition the air and make it dryer. Nothing wrong with that but the problem is during the cold freezing temperatures below 4C° the ac compressor won’t start although been selected ON or auto and after a while you had been driving the car the engine bay temperature will rise and the ac will kick in and usually that happens when you just about to arrive at your destination. What happens next is the AC evaporator becomes colder than before because the compressor has started and shortly after you turn the car off and here is the problem where it starts from. You turn off your car and walk away, but there is air coming inside the cabin that passes through ice cold ac evaporator and through hot heater core then straight into the cabin and particularly windscreen, this air stream brings a lots of moisture as a result of air passing through two bodies worth very large temperatures margins, one is very cold perhaps 4C° and the other is around 40-60C°. 
If your AC was switched off manually, your car hvac system either in manual or auto mode will not start your ac compression at all even after long drive, your cabin would be dry and aired by the heating only as in the older cars and you will have less moisture formed along the air ducts and windscreen. 

A fair and detailed description but, I'm not in the know on how this C-HR system physically works so this is just my take on how I feel it should operate and I am open to be educated otherwise.

I would have imagined when the car shuts down the air intakes (and may be more) should go into close position and the frost/ice should melt from the evaporator and drain out under the car into the atmosphere? 

This could lead to other reasons causing the problems, evaporator drain(s) blocked, duct servo(s) not operating or ventilation system not shutting down correctly due to system fault in the control unit. 

 

[Trewithy]

When switched off the default position for the flaps in the car is outside air.  You can check this by selecting recirc.  Then when you power off wait 60 seconds and you will hear the flap open.  If don't hear it open then adjust Efficient Ventilation in vehicle settings.  Thats how it is in my Corolla.

[TonyHSD]

I usually spent 12 hrs in my car on daily basis when at work.  
I noticed sometimes  around 10-15 minutes after the car been switched off the hvac system is operating its flaps as I can hear the actuators are working. Interesting it doesn’t do it every time therefore I am not sure what is the reason about these flap movements.
 I personally do not like using AC during winter and because I spent enough time in the hvac system has plenty of time to warm up and dry the interior with heating only and add fresh air from outside. Even my hvac settings are set manually the whole process is still automatic and the whole system works at its best performance all the time, I just have my own preferences that I love to be exact as I wish and not as the car believes it’s better. Those are my settings:  

During winter:
Temperature of the interior set at 22C°.  
Air flow towards windscreen and feet. 
Air intake from outside. 
Fan speed 2. 
AC off. 
 

During summer: 

Temperature set at 22C°. 
Air flow towards middle of dashboard and feet. 
Air intake from outside. 
Fan speed 2. 
AC off or on depending on outside temperatures, anything above 18C° I turn it on and the system chooses whether to suck air from outside or recirculating or switches in between. 
I never had any moisture issues at all. My ac is working great when I need it, although I don’t even turn it on for long periods  4-6 months for example. 
 

[GBgraham]

4 hours ago, TonyHSD said:

When switched off the default position for the flaps in the car is outside air.  You can check this by selecting recirc.  Then when you power off wait 60 seconds and you will hear the flap open.  If don't hear it open then adjust Efficient Ventilation in vehicle settings.  Thats how it is in my Corolla.

 

I usually spent 12 hrs in my car on daily basis when at work.  
I noticed sometimes  around 10-15 minutes after the car been switched off the hvac system is operating its flaps as I can hear the actuators are working. Interesting it doesn’t do it every time therefore I am not sure what is the reason about these flap movements.
 I personally do not like using AC during winter and because I spent enough time in the hvac system has plenty of time to warm up and dry the interior with heating only and add fresh air from outside. Even my hvac settings are set manually the whole process is still automatic and the whole system works at its best performance all the time, I just have my own preferences that I love to be exact as I wish and not as the car believes it’s better. Those are my settings:  

During winter:
Temperature of the interior set at 22C°.  
Air flow towards windscreen and feet. 
Air intake from outside. 
Fan speed 2. 
AC off. 
 

During summer: 

Temperature set at 22C°. 
Air flow towards middle of dashboard and feet. 
Air intake from outside. 
Fan speed 2. 
AC off or on depending on outside temperatures, anything above 18C° I turn it on and the system chooses whether to suck air from outside or recirculating or switches in between. 
I never had any moisture issues at all. My ac is working great when I need it, although I don’t even turn it on for long periods  4-6 months for example. 
 

Appreciated Kevin and Tony, with two views on the workings but in my climate our cars very rarely get set anywhere the 20's

I am not sure why the flaps would be set to be open on shut down, I can't think of a justified reason for this. It also does not lead to solving the problem of condensation. 

Not sure if all, but cars used to have one way vents built into the interiors through the cars "C" pillars or the internal of  rear quarter panels, this was to prevent internal air pressure to build inside the car mainly due to temperature and to prevent the outside atmosphere to enter on cooling, so the opening of air intake on shut down doesn't make any sense to me.

No doubt one day light will be shone on the condensation issues.