Vibration while braking with AC on

[RichV]

My 2014 Spark EV has a very pronounced vibration that I can feel in the whole car while slowing down and ONLY with the air conditioning running. It has done it since new but has been most noticeable with our recent 110 degree heat wave.

The dealer can't seem to find anything wrong. I plan to go for a ride with the technician later this week to confirm the issue.

Has anyone else experienced this? Is it considered normal?

[Zoomit]

Definitely not normal. It may be warped rotors, but I don't know how you'd do that in this car (without trying) but that wouldn't be associated with the AC. I wouldn't think the AC, or any load on the battery, would affect the regen braking.

Please do let us know what the tech says.

[RichV]

It is definitely not a warped rotor issue based on the feel of things. The first explanation from the service advisor was that my non-OE wheels and tires were causing the ABS to activate. I am a certified BMW I3 technician and ex-race car driver; this is definitely NOT the issue

My best guess would be something in the A/C system is shifting during load changes causing the pump vibration to be felt throughout the vehicle. It's possible it is something driveline related, but that would not explain the issue being present only with the A/C running.

I'm going to stop by tomorrow and go for a ride with the technician to verify the issue. If it is claimed to be normal, I will request that another Spark EV be provided that I am able to compare it to. If not I may reach out and see if I can find someone locally to compare cars.

[Zoomit]

In that case, I'll wager that a bolt holding the pump for the AC coolant was not properly torqued and has fallen out. It's a long shot, but the only thing I can think of.

But you said it's been that way since new, so maybe an assembly error?

[NORTON]

RichV,

I experience the exact same thing. It's only when the AC is running and it feels like it only starts around the time the system is transitioning from regen braking to friction braking.
Then once at stop it is gone. It some sort of harmonic vibration. I assume the AC compressor is mounted to the drive unit to help with vibration isolation.

I've learned to live with it. The local Chevy dealership has no experience with the Spark EV, so I'm saving my visit for "The Big One",, which hopefully will never come.

Side Note: You can test just your friction brakes by shifting to Neutral and give the brakes hell, for once. They have an extremely easy life.

EDIT: It does not seem noticeable lately with the temps not in the 100°'s. The AC compressor is multi-speed. Maybe when it runs at lower power the harmonics aren't noticeable.

[WattEV]

Add me to the list. Mine does this same exact thing, usually when it's very hot outside and the A/C system is under load. I haven't taken it in, because quite frankly, I don't have time to waste for the dealer to say there is nothing wrong. haha I thought I read somewhere a while ago there was a software update, but I don't know. It is annoying though.

[nozferatu]

This has nothing do with the friction brakes being warped or A/C. It has more to do with the regen system and how it works.

It happens when the temperature is particularly warm so A/C is almost always running.

My guess is that when things get really hot, the regen system is less active and standard braking takes over. However, it's pulsed. This is the feeling I get...like it's a very very rapid and very mild form of antilock.

[NORTON]

This has nothing do with the friction brakes being warped or A/C. ...

This could easily be tested.
Next time you are experiencing this vibration/harmonic, try to repeat it with the AC off.
I haven't had it for a while. It does seem to be outside temp related. We need to test if it is AC operation related.

[WattEV]

This has nothing do with the friction brakes being warped or A/C. It has more to do with the regen system and how it works.

It happens when the temperature is particularly warm so A/C is almost always running.

My guess is that when things get really hot, the regen system is less active and standard braking takes over. However, it's pulsed. This is the feeling I get...like it's a very very rapid and very mild form of antilock.

I also agree 100% it is regen related, however, turning the A/C on triggers the vibration. It is not the A/C system itself making the vibration, but something electrically is triggering this vibration phenomenon when the A/C is on. I do not get any of this vibration during regen with the A/C off, even when it's over 100 outside.

My A/C is usually always off, so for me, it only happens when I turn the A/C on and I live where it is usually always warm. In fact, it's been in the 90's to 100's the past few weeks for me. Also, I have turned of the "Auto Defog" feature in the setup menu so that my A/C does not automatically turn on even when it says it's off just to be sure it's off.

[MrDRMorgan]

I have a very slightly used 2014 Spark EV 2LT I purchased earlier this month (1500 miles). I came across this thread and thought it was an interesting problem for 2014 Spark EVs only to find out today that I have the same problem - over 100 deg. F outside and A/C on with fan at 4 bars. Yep! As I applied the brakes I heard and felt the vibration. There were two people in the vehicle. I turned off the A/C and tried again - no vibration.

I am fortunate to also have a 2015 Spark EV 2LT and I plan to run the same test to see if the problem was corrected for 2015. I have noticed that the regeneration action in the 2014 is much stronger than that in the 2015. Perhaps GM was aware of this and made the fix. I will advise when I have completed the test.

Dennis

UPDATE: I was able to duplicate the same vibration on my 2015 Spark EV 2LT but it was not as noticeable as that on the 2014 Spark EV.