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Heat pump compressor short cycling
- Thread starter Sam T
- Start date
I’m still yet to see anyone else show me their short cycling compressor, does yours do it too?
FWIW in all your videos the compressor is only cycling at 1600rpm. That's very low. If it was really working hard it would be at 9000rpm. It really seems like the cooling demand is very low and the system is just cycling the compressor on and off to save energy.
I will say it again, if the compressor was hard faulting randomly due to a system defect there would be a bunch of alerts.
I will also say it again: the service screen is to tell the technician things, it's not for us. Aside from the fact that it looks weird to you you have not actually explained what symptoms you are having.
I too have played around in the service screen. It is buggy. It thinks the passenger seat is occupied even after I get up. The SCCM screen doesn't register some of the steering controls that I know work fine. Tesla doesn't really care about the service menu as it's not customer facing.
I will say it again, if the compressor was hard faulting randomly due to a system defect there would be a bunch of alerts.
I will also say it again: the service screen is to tell the technician things, it's not for us. Aside from the fact that it looks weird to you you have not actually explained what symptoms you are having.
I too have played around in the service screen. It is buggy. It thinks the passenger seat is occupied even after I get up. The SCCM screen doesn't register some of the steering controls that I know work fine. Tesla doesn't really care about the service menu as it's not customer facing.
The Tesla Model Y HVAC works best if you do the following:
Set HVAC to Auto.
Set Fan Speed to High (Note that when the HVAC is in the Auto setting the Fan Speed control functions as a speed limiter, not a fixed fan speed). In HVAC Auto mode if you set the Fan Speed to Low or Medium, in very hot or cold weather, the HVAC system may not be able to move enough air to adequately cool or heat the passenger cabin.
Precondition for a few minutes (5 minutes in summer, 8 minutes in winter) before driving.
Turn on Recirculate Cabin Air during the hottest weather so the HVAC system will not have to work as hard.
Add a good ceramic tint film to the windshield, side windows and rear hatch glass. The glass roof is factory treated to reject UV rays and IR (heat) but you can also tint the glass roof if you want.
Install a mesh fabric sunshade as these really do make a difference during the daytime hours (sun does not bake the top of your head.)
Use Cabin Overheat Protection (COP) (COP remains active for 12 hours after you park.) If you use the COP Fan Only mode the energy usage is 1/3rd as much as if the AC runs when COP is activated.
The Tesla Model Y's compressor will run even if you turn off the HVAC system. This variable speed compressor runs to cool the following: the high voltage battery pack, front and rear drive units, high voltage power controllers, Model Y's computer and the PCS and the on-board charger. The compressor also cools itself. The passenger cabin is heated and cooled via the cabin heat exchanger (coolant to passenger cabin air heat exchange). The high voltage components are cooled via the chiller (liquid to liquid heat exchange.)
Set HVAC to Auto.
Set Fan Speed to High (Note that when the HVAC is in the Auto setting the Fan Speed control functions as a speed limiter, not a fixed fan speed). In HVAC Auto mode if you set the Fan Speed to Low or Medium, in very hot or cold weather, the HVAC system may not be able to move enough air to adequately cool or heat the passenger cabin.
Precondition for a few minutes (5 minutes in summer, 8 minutes in winter) before driving.
Turn on Recirculate Cabin Air during the hottest weather so the HVAC system will not have to work as hard.
Add a good ceramic tint film to the windshield, side windows and rear hatch glass. The glass roof is factory treated to reject UV rays and IR (heat) but you can also tint the glass roof if you want.
Install a mesh fabric sunshade as these really do make a difference during the daytime hours (sun does not bake the top of your head.)
Use Cabin Overheat Protection (COP) (COP remains active for 12 hours after you park.) If you use the COP Fan Only mode the energy usage is 1/3rd as much as if the AC runs when COP is activated.
The Tesla Model Y's compressor will run even if you turn off the HVAC system. This variable speed compressor runs to cool the following: the high voltage battery pack, front and rear drive units, high voltage power controllers, Model Y's computer and the PCS and the on-board charger. The compressor also cools itself. The passenger cabin is heated and cooled via the cabin heat exchanger (coolant to passenger cabin air heat exchange). The high voltage components are cooled via the chiller (liquid to liquid heat exchange.)
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1. The climate uses between 20-60% of total energy consumed. It would be more energy efficient to simply leave it on, in fact it would be more energy efficient to drive up a 100m mountain than to cycle it off and on repeatedly almost constantly.
2. The Tesla Y, like every other system ever created since the dawn of man, is not perfect. I’ve read of at least 3 others on this forum with the same issues with no errors, yet their problems were solved with hardware replacements. A) super-manifold temperature sensor b) compressor replacement c) 3 different temperature sensors
3. Your tone is condescending AF. The Tesla HVAC has been riddled with problems for years, some people have had multiple compressor replacements. Giga Berlin has a recall due to manufacturer error. I found another tsb (internal) directing temperature sensor replacements.
4. I’m not going waste my time on this forum looking for answers when there’s nothing wrong. Assuming I haven’t already tried every single setting and alternative is bonkers.
I’ll say it again, BONKERS
Reject is the wrong word entirely. Radiation is either reflected or absorbed. There is no such thing as rejection.
So what happens to the UV? I don't actually know. Some will no doubt be reflected but I suspect most of it is absorbed as heat which warms the glass. Thankfully it's low energy stuff.
The infra red definitely gets absorbed heats up the glass which heats up the air next to the glass by conduction. Outside hotter air wafts away. Inside air gets hotter and hotter and hotter...
IR rejection is a total nonsense easily dismembered by simple observation.
OK, what about the ceramic tint films? Do the ceramic tint films reflect or absorb the IR and UV radiation? While on the subject, laminated glass filters out most UV rays. Does this UV get absorbed?
Backing up a little, I omitted the transmitted radiation as it wasn't under discussion.
If it isn't transmitted or reflected the only other option is absorption.
I honestly do not know if UV and IR bounce off ceramic*, *buzzword for "special super duper", when it applies to a vinyl film off a roll. It matters that UV doesn't come inside and give you sunburn.
IR reflects off silvered and polished surfaces so if "ceramic" mimics that then a definite possiblity that would be easy to prove.
Just no "rejection".
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The symptoms for anyone who cares are fluctuating temperatures from AC, roughly 6C difference, every minute or two, sometimes more often, sometimes less.
It happens at night, during the day, in tunnels- anywhere. It seems to happen more frequently during humid conditions.
Energy consumption for climate is through the roof. How a 5kw compressor uses as much energy as a motor is beyond me.
Range is drastically reduced- as bad as half the stated range displayed on the energy app.
Errors displayed related to LV battery UV, first warnings in service mode for 20mins at a time, then customer facing saying pull over immediately with no acceleration.
I’ve tried the glass shade cover, I’ve tried auto for weeks, I’ve tried higher fan settings for hours, although a slight improvement - no big difference.
Sometimes the AC works perfectly, for hours at a time, energy consumption is better than normal, no temperature fluctuations, cabin feels great. Then I’ll get out of the car and get back in, boom, back to problems.
Once the cycling begins the only way to get it back to normal is to keep turning it off for a few mins and turn it back on and eventually maybe it’ll work as it should (40km each 10%)
Software resets, soft, hard, reinstalling firmware all have the same effect - good for a few hours then back to bad.
It’s not normal, it’s not efficient, it’s hella sus to say it’s just me when others here have the same problem.
If an engine had a fault and all of them do it, guess what, it’s still a fault and it won’t be recalled until the customers know about it and report it.
Tesla Y drivers are not gonna know there’s a problem when they don’t calculate their real range. It’s the first symptom for any car, gas or battery. So the problem could be much more widespread than reported, especially if service centres tell drivers everything is ok, other mechanics don’t want to touch the car and there’s an increasing trend to just put the display on % and forget about it.
For example, this is today, it’s 17C, all the green areas are when I turned off the AC just to try get some decent range out of it. As you can see I’ve used 20% of energy on the climate. It’s set to 20C, fan 4, rear on. If I was to keep the AC on all the time it would be much worse.
It happens at night, during the day, in tunnels- anywhere. It seems to happen more frequently during humid conditions.
Energy consumption for climate is through the roof. How a 5kw compressor uses as much energy as a motor is beyond me.
Range is drastically reduced- as bad as half the stated range displayed on the energy app.
Errors displayed related to LV battery UV, first warnings in service mode for 20mins at a time, then customer facing saying pull over immediately with no acceleration.
I’ve tried the glass shade cover, I’ve tried auto for weeks, I’ve tried higher fan settings for hours, although a slight improvement - no big difference.
Sometimes the AC works perfectly, for hours at a time, energy consumption is better than normal, no temperature fluctuations, cabin feels great. Then I’ll get out of the car and get back in, boom, back to problems.
Once the cycling begins the only way to get it back to normal is to keep turning it off for a few mins and turn it back on and eventually maybe it’ll work as it should (40km each 10%)
Software resets, soft, hard, reinstalling firmware all have the same effect - good for a few hours then back to bad.
It’s not normal, it’s not efficient, it’s hella sus to say it’s just me when others here have the same problem.
If an engine had a fault and all of them do it, guess what, it’s still a fault and it won’t be recalled until the customers know about it and report it.
Tesla Y drivers are not gonna know there’s a problem when they don’t calculate their real range. It’s the first symptom for any car, gas or battery. So the problem could be much more widespread than reported, especially if service centres tell drivers everything is ok, other mechanics don’t want to touch the car and there’s an increasing trend to just put the display on % and forget about it.
Thank you for the tips I do appreciate it, but I’ve been trying what you said for 3 months with no real change. Yea the sun shade helps, but the energy consumption is still too high by a long way.
For example, this is today, it’s 17C, all the green areas are when I turned off the AC just to try get some decent range out of it. As you can see I’ve used 20% of energy on the climate. It’s set to 20C, fan 4, rear on. If I was to keep the AC on all the time it would be much worse.
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I didn't mean to be condescending, sorry.
Ok, now this is very interesting... Did you file a service ticket for this??
I'll say it again. Get the service manager to take your car for a week.
If they still deny there is anything wrong you will have the energy use report to put in your complaint to whoever runs the motor vehicle commerce supervision over there. Over here it is a bit like a small claims court for complaints against car dealers.
If they still deny there is anything wrong you will have the energy use report to put in your complaint to whoever runs the motor vehicle commerce supervision over there. Over here it is a bit like a small claims court for complaints against car dealers.
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