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Discussion Starter · #1 ·
I recall a post in a thread on this Forum a few months ago in which a contributor mentioned that in cool weather he set his air conditioner on what he thought should provide a comfortable temperature. He found that initially the car was reasonably comfortable, but after that initial warm-up period, the vents seemed to produce cool air, despite there being no material change to the outside temperature.

In Australia, we're transitioning from an unseasonably cool spring to summer and my experience over winter was much the same as that referred to above. I managed the discomfort - to some extent - by angling the vents away from people in the cabin.

Now, with a few warmer days, I'm finding the EQA's air conditioner seems to struggle to maintain a comfortably cool cabin temperature.

I contrast both heating and cooling with my wife's 2016 B250, which consistently maintains a comfortably warm cabin temperature during winter and a similarly cool temperature in summer - even on really hot days (over 40 degrees Celsius).

Have other EQA owners had similar experiences - and, more particularly, has anyone discovered the settings necessary to get the EQA air conditioning system to heat and cool as well as a good ICE equivalent?
 

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I recall a post in a thread on this Forum a few months ago in which a contributor mentioned that in cool weather he set his air conditioner on what he thought should provide a comfortable temperature. He found that initially the car was reasonably comfortable, but after that initial warm-up period, the vents seemed to produce cool air, despite there being no material change to the outside temperature.

In Australia, we're transitioning from an unseasonably cool spring to summer and my experience over winter was much the same as that referred to above. I managed the discomfort - to some extent - by angling the vents away from people in the cabin.

Now, with a few warmer days, I'm finding the EQA's air conditioner seems to struggle to maintain a comfortably cool cabin temperature.

I contrast both heating and cooling with my wife's 2016 B250, which consistently maintains a comfortably warm cabin temperature during winter and a similarly cool temperature in summer - even on really hot days (over 40 degrees Celsius).

Have other EQA owners had similar experiences - and, more particularly, has anyone discovered the settings necessary to get the EQA air conditioning system to heat and cool as well as a good ICE equivalent?
I haven’t noticed a problem with my air conditioner cooling function (cars in Scotland don’t need cooling very often!) but I do think there’s a problem with the heating of the cabin. I have set the temperature to 19° C which produced a comfortable temperature in my last car but my EQA seems to put out warm (not hot) air for around 25 - 30 minutes then for the rest of the journey it blows cold air, cold enough to make my fingers cold.
It’s not a problem for short journeys but I was sufficiently concerned that I recently put a room thermometer in the door pocket to see if it would confirm what I was feeling. The heater does raise the temperature but only to around 14° to 16° depending on ambient temperature then starts to blow cold and the temperature on the thermometer starts to drop, this continues until I stop and on restarting even after a few minutes the heater immediately starts to blow warm air again. My thermometer is not ideal in that it’s a bit slow to react and so far I’ve not driven long enough to see how cold it will get but it’s not comfortable. The car has done this from new but when I brought it up with the dealer they couldn’t see a problem as there was warm air coming out of the vents when they started the car.
Turning up the temperature setting does produce more heat but it still blows cold air after a while and won’t heat up again until the car is stopped and started again.
 

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Discussion Starter · #3 · (Edited)
Thank you for your prompt reply post, FDR. Maybe the earlier post I recalled - some months ago - was also yours; the comments in respect to heating were very similar to your report above.

I assume the EQA is heated from the battery cooling system, rather than the air conditioner being a reverse cycle system. If my assumption is correct, it would explain the heating behaviour we've noted: once the battery system is heated to the optimum temperature range, the coolant heating system backs off, irrespective of passengers' desire to maintain a specific cabin temperature.

I wonder whether this apparent shortcoming could be resolved via a software adjustment. I suspect the parameters controlling the coolant temperature have primary regard for energy efficiency, but when all's said and done, the vehicle is a means to transport people in comfort, not a platform to demonstrate energy efficiency. Perhaps there's a need for a re-think of priorities because, in my opinion the heating function, in particular, isn't 'Mercedes quality'.

I wonder how the EQA compares in this regard with other Mercedes EVs and with other EVs? I am sitting in front of a thermostatically controlled electric fan-forced heater at the moment: prompts the thought that - putting safety to one side for a moment - in a Hyundai Ioniq 5 one could plug that electric heater into its in-cabin power socket!

I am not surprised to hear that cooling isn't such a problem in Scotland. Presuming that the EQA's cooling function is provided by a conventional air conditioning system (refrigerant compressor / evaporator), I'll experiment further with different settings to see if I can achieve 'Mercedes quality' comfort in our warmer weather.
 

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When I first got the EQA and noticed the problem I thought it was like a combustion engine in that the heater puts out more heat when the engine is working hard then reduces when the engine is cruising, so I assumed the battery/motors were working harder when cold. This didn’t explain why the EQA didn’t try to maintain the set cabin temperature using the same heat source it used at start off.
Your assumption that the battery temperature control system is the source of cabin heat makes more sense and I wonder if that would mean that adding heat to the battery temperature system in order to heat the cabin would lead to overheating the battery.
What I don’t understand is why the heater seems to start a new cycle of blowing warm on restarting after only being stopped for a few minutes, I am sure that on the occasions I noticed this, there wasn’t time for the battery to have cooled enough to need further heating and yet the cabin heater stayed on, as near as I could tell, for its usual 20 - 30 minutes.
 

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Discussion Starter · #5 ·
What I don’t understand is why the heater seems to start a new cycle of blowing warm on restarting after only being stopped for a few minutes, I am sure that on the occasions I noticed this, there wasn’t time for the battery to have cooled enough to need further heating and yet the cabin heater stayed on, as near as I could tell, for its usual 20 - 30 minutes.
Perhaps, while the vehicle is idle there's an accumulation of thermal load in the system, which is dissipated upon re-starting - hence the short-term supply of warmer air.

Does the lack of other responses to this topic mean that other EQA operators don't have an issue with the car's cabin heating system, or have they simply not seen this thread or aren't sufficiently motivated to contribute to it?
 

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One thing that’s occurred to me is the heating problem is reminiscent of a sticking thermostat. When the cabin temperature reaches a level that the thermostat switches off instead of cycling on and off to maintain the temperature, it sticks in the off position, then when the car is stopped and restarted the thermostat is reset and works until it reaches the cut off point again.
 

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Discussion Starter · #8 ·
Aye, it looks like it’s just you and me mate!
Maybe the others only drive for 25 minutes at a time so their heating doesn’t have time to shut down.
I'm pleased to get your insights from a cold climate, but it would be interesting to get more contributions, irrespective of individuals' perspective - particularly in regard to heating.

It was a warm to hot day here yesterday (33-34 degrees C) and whilst on a journey of 10 km or so, I played with a couple of the air conditioning buttons and suddenly the system produced a blast of cool air, which was sustained for the remainder of the journey. I'm not sure what wasn't previously set correctly, but the air conditioner now seems to be producing 'Mercedes quality' cooling.

One thing that’s occurred to me is the heating problem is reminiscent of a sticking thermostat. When the cabin temperature reaches a level that the thermostat switches off instead of cycling on and off to maintain the temperature, it sticks in the off position, then when the car is stopped and restarted the thermostat is reset and works until it reaches the cut off point again.
I've noticed what look like various sensors wired into the cooling system. One wonders whether they're all working as they should (on your car) - although given that my experience (regarding cabin heating) has been similar to yours, I suspect the inadequate heating is due more to a design shortcoming than an individual component failure.

I have reported my concerns about this to our dealership and they've offered to inspect my car, but unless we get another unseasonable cold spell - and a workshop time slot to coincide (wait times are currently about 4 weeks) - I suspect it won't be worthwhile them inspecting my car for another 6 months or so (next southern hemisphere winter).

In the meantime, I've purchased a 4-sensor wireless barbecue thermometer to monitor coolant temperatures - or at least the outside of three coolant hoses - to get some understanding of the temperatures involved. The temperature sensors are cable-tied to the respective coolant hoses and one sensor measures the under-bonnet ambient temperature. So far, I've only made one journey (about 10 km) with that system fitted and the ambient temperature was about 25C, maximum under-bonnet temperature about 40C and the three hoses' maximum temperatures were between 44 and 47C. I think one of those hoses - one to the left of the 12 volt battery (looking towards the cabin) - feeds the cabin heater and it produced the highest maximum temperature, but, of course, my air conditioning system was set to cool, so I suspect the coolant bypassed what I assume is a cabin heating coolant heat exchanger (small radiator).

Yes, with my front shutter monitoring system also in place, my car is currently a bit of a mobile test bed! On that score, apart from an initial, brief 'close and reopen' sequence, the shutters remained open for the entirety of both of my 10 km journeys yesterday.
 

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I may try my dealer again to see if they’ve had any other complaints about this as it’s about a year since I mentioned it to them and presumably they will have sold more EQAs since then. They may be able to test sensors or something, if not I don’t suppose they’ll be keen to drive it around for half an hour waiting for the fault to show. Daytime temperatures here are around 3°C to 5°C so a fully functional heater is starting to be needed.
It’s good you got your cooling to work by playing with the controls, I can get the heating to work by doing something similar, if I increase the set temperature by 1 or 2 degrees after the initial heating has stopped it starts another cycle of heating but this doesn’t produce a permanent cure. It does show that the hot air is available if only the car would switch it on.
Your shutter monitoring is interesting and would seem to show they’re not just for streamlining but will open whenever the system needs cooling, not only when the car is parked.
 

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Discussion Starter · #10 ·
I may try my dealer again to see if they’ve had any other complaints about this as it’s about a year since I mentioned it to them and presumably they will have sold more EQAs since then. They may be able to test sensors or something, if not I don’t suppose they’ll be keen to drive it around for half an hour waiting for the fault to show. Daytime temperatures here are around 3°C to 5°C so a fully functional heater is starting to be needed.
It’s good you got your cooling to work by playing with the controls, I can get the heating to work by doing something similar, if I increase the set temperature by 1 or 2 degrees after the initial heating has stopped it starts another cycle of heating but this doesn’t produce a permanent cure. It does show that the hot air is available if only the car would switch it on.
I would be inclined to try the dealer again, because I suspect the MB network is to some extent learning on the run with its EVs - although one would expect that something as fundamental as a heating system which sustains the desired cabin temperature should have been covered during R&D testing, if not, initial design.

Your shutter monitoring is interesting and would seem to show they’re not just for streamlining but will open whenever the system needs cooling, not only when the car is parked.
My observations at this stage indicate that various parameters dictate shutter opening and closing. I will report on that in more detail in the relevant thread.
 

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I had a 3-hour drive today in 30-36 deg C. Happy to report that the cooling was OK. Temperature was set @ 22.5 on AUTO. The fan speed was definitely higher compared to other days when the temperature was below 30.
 

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Discussion Starter · #12 ·
I had a 3-hour drive today in 30-36 deg C. Happy to report that the cooling was OK. Temperature was set @ 22.5 on AUTO. The fan speed was definitely higher compared to other days when the temperature was below 30.
Good to hear!

Sustained, consistent heating seems to be the issue. Not sure where you are in Australia, but have you operated the car on a longish drive in cool - or better still, cold conditions?
 

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Good to hear!

Sustained, consistent heating seems to be the issue. Not sure where you are in Australia, but have you operated the car on a longish drive in cool - or better still, cold conditions?
I am on the east coast, travelling mainly between Gold Coast, Brisbane and Sunshine Coast. Low temperatures near zero are uncommon (fortunately for me!). Back in July, I had a 100 km long trip at 6 a.m. at around 12-13 deg. I usually have PECC on prior to start and didn't notice any noticeable change in temperature inside during the drive. I have also noticed that PECC on prior to start with the car plugged in helps in keeping the range closer to the value stated at the start of the drive.
 

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I haven’t noticed a problem with my air conditioner cooling function (cars in Scotland don’t need cooling very often!) but I do think there’s a problem with the heating of the cabin. I have set the temperature to 19° C which produced a comfortable temperature in my last car but my EQA seems to put out warm (not hot) air for around 25 - 30 minutes then for the rest of the journey it blows cold air, cold enough to make my fingers cold.
It’s not a problem for short journeys but I was sufficiently concerned that I recently put a room thermometer in the door pocket to see if it would confirm what I was feeling. The heater does raise the temperature but only to around 14° to 16° depending on ambient temperature then starts to blow cold and the temperature on the thermometer starts to drop, this continues until I stop and on restarting even after a few minutes the heater immediately starts to blow warm air again. My thermometer is not ideal in that it’s a bit slow to react and so far I’ve not driven long enough to see how cold it will get but it’s not comfortable. The car has done this from new but when I brought it up with the dealer they couldn’t see a problem as there was warm air coming out of the vents when they started the car.
Turning up the temperature setting does produce more heat but it still blows cold air after a while and won’t heat up again until the car is stopped and started again.

sharpdetail
Shockingly cheap and easy. I got hit by a rock on the interstate and my windshield was cracking more and more every week, not stopping. I called Auto Glass Now Tucker as it was close to me, and I'm so glad I did. The repair was about 20 minutes. My car windshield looks amazing, and the price was 180, below any deductible imaginable.
 

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Good to hear!

Sustained, consistent heating seems to be the issue. Not sure where you are in Australia, but have you operated the car on a longish drive in cool - or better still, cold conditions?
Sorry for coming into this conversation a bit late, but I have noticed exactly the same problem with my EQA350 in this current cold weather we are having in the UK but I did not notice a converse problem with the cooling in the hot summer. I wonder whether it is a software issue linked to maintaining range? In the summer I was typically getting 3.3 to 3.4 m/kWh but recently it has dropped to only 2.2 to 2.4 m/kWh and I am COLD inside, having to push the temperature up and up to get the heat to appear!
 

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Discussion Starter · #16 ·
Although the sample size (contributors to this Forum topic) is small, cabin heating seems to be an EQA shortcoming. It surprises me that Benz left such an important aspect of the car underdeveloped in the design and R&D phase of the car's genesis. Hopefully, enough customers will make more than casual complaints to their supplying dealerships that Benz will recognise the issue and something will be done to reduce the problem, if not alleviate it.
 

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As in my previous post (#7) I am more convinced now that there’s a thermostat sensor somewhere been sticking. I had fixed a thermometer between the front seats and inserted a second into the centre heater vent on the dashboard to check what is happening rather than going by what I was feeling. Ironically the weather has been cold enough (temperatures well below 0°C last week) to get a good test but because of snow and ice on the roads I have only been doing short journeys, however today temperatures are back above freezing (10°C now) and I had a continuous journey where the heater has worked perfectly. I had the heater set at 20°C and my cabin thermometer was showing 19.5°C, the thermometer in the vent was reading 25°C when the heater started to blow cooler air. Unlike previous times, when the cold blast continued until the car was stopped and restarted, after a few minutes it was back blowing warm air, so it would appear to be cycling correctly now to maintain the set temperature. Here’s hoping it continues!
 

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Discussion Starter · #18 ·
Interesting, FDR. I too hope your heating system has recognised the error of its ways and corrected itself - permanently!

On a related note, I am still working on my radiator shutter opening/closing project, which includes monitoring three coolant hose temperatures. The project has been delayed due to various circumstances, but I hope my findings can, in due course, shed some light on cooling system behaviour (including temperatures) on the 'engine' bay side of the firewall.
 

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I'm pleased to get your insights from a cold climate, but it would be interesting to get more contributions, irrespective of individuals' perspective - particularly in regard to heating.

It was a warm to hot day here yesterday (33-34 degrees C) and whilst on a journey of 10 km or so, I played with a couple of the air conditioning buttons and suddenly the system produced a blast of cool air, which was sustained for the remainder of the journey. I'm not sure what wasn't previously set correctly, but the air conditioner now seems to be producing 'Mercedes quality' cooling.



I've noticed what look like various sensors wired into the cooling system. One wonders whether they're all working as they should (on your car) - although given that my experience (regarding cabin heating) has been similar to yours, I suspect the inadequate heating is due more to a design shortcoming than an individual component failure.

I have reported my concerns about this to our dealership and they've offered to inspect my car, but unless we get another unseasonable cold spell - and a workshop time slot to coincide (wait times are currently about 4 weeks) - I suspect it won't be worthwhile them inspecting my car for another 6 months or so (next southern hemisphere winter).

In the meantime, I've purchased a 4-sensor wireless barbecue thermometer to monitor coolant temperatures - or at least the outside of three coolant hoses - to get some understanding of the temperatures involved. The temperature sensors are cable-tied to the respective coolant hoses and one sensor measures the under-bonnet ambient temperature. So far, I've only made one journey (about 10 km) with that system fitted and the ambient temperature was about 25C, maximum under-bonnet temperature about 40C and the three hoses' maximum temperatures were between 44 and 47C. I think one of those hoses - one to the left of the 12 volt battery (looking towards the cabin) - feeds the cabin heater and it produced the highest maximum temperature, but, of course, my air conditioning system was set to cool, so I suspect the coolant bypassed what I assume is a cabin heating coolant heat exchanger (small radiator).

Yes, with my front shutter monitoring system also in place, my car is currently a bit of a mobile test bed! On that score, apart from an initial, brief 'close and reopen' sequence, the shutters remained open for the entirety of both of my 10 km journeys yesterday.
I noticed that the cabin temp is best managed if it is set auto, after selecting the wantend temperature.
That seems to be the best way for my 250 EQA here in the 40 degrees days in Perth AU
 
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