HVAC barely blowing air (possibly blocked somewhere?)

[ljwobker]

Within the past couple of days, the HVAC in my 2020 Model S has been behaving funny (and poorly). Regardless of the fan settings, there's no more than a trickle of air coming through the vents. The air is definitely conditioned (it's cold and dry) but the volume of air is very low so it doesn't really cool the car down. When the fan speed is increased manually I can hear more sound (the fans are obviously running and responding to the speed control) but it doesn't make it to the cabin.

Troubleshooting so far:
- happens regardless of auto vs. manual
- happens regardless of selected output (windscreen vs. face vs. feet)
- MCU screen feels quite warm to the touch (possibly the air that cools the unit is part of what's blocked?)

Anyway.. figured I'd at least check to see if anyone had ever experienced anything similar before I take it in...

 

[Ostrichsak]

Is it hot out? If it's a hot day your car may divert cooling resources to your battery pack.

 

[SarahsDad]

Sounds like the evaporator may be freezing over with condensation and blocking airflow. If you park it outside in the heat for a few hours does it get better? It's been crazy humid here in NC and that makes it more likely. It happened to me once in a Honda Odyssey (but not in the Tesla). Or you may have low refrigerant (which makes it paradoxically colder apparently and freezes over more easily).

 

[ljwobker]

So I'm pretty sure it was just the coils freezing over. Turning off the A/C for a little while and letting the fan run cleared it up, but I'm still a little concerned that it happened in the first place. And sure, NC has been hot (and humid as hell) but it's not like we're Arizona heat or Florida humidity.

The one thing I did think about is that both times this happened was after long stretches of driving in the mountains, with LOTS of regen occurring. Over a 30mi stretch it took 38 minutes, and we did it at an average of 90wh/mi, which means there was some serious regen going on. The other stretch was driving up and down, so plenty of regen on the down and plenty of high-output on the up.

I cancelled my service appointment because I'm pretty sure I have a workaround (just run the fan) and until I can more reliably reproduce it, it seems dumb to just take it in there when it's working as they'll likely tell me "we can't find anything wrong".

 

[tigger2]

So I'm pretty sure it was just the coils freezing over. Turning off the A/C for a little while and letting the fan run cleared it up, but I'm still a little concerned that it happened in the first place. And sure, NC has been hot (and humid as hell) but it's not like we're Arizona heat or Florida humidity.

The one thing I did think about is that both times this happened was after long stretches of driving in the mountains, with LOTS of regen occurring. Over a 30mi stretch it took 38 minutes, and we did it at an average of 90wh/mi, which means there was some serious regen going on. The other stretch was driving up and down, so plenty of regen on the down and plenty of high-output on the up.

I cancelled my service appointment because I'm pretty sure I have a workaround (just run the fan) and until I can more reliably reproduce it, it seems dumb to just take it in there when it's working as they'll likely tell me "we can't find anything wrong".

I'm experiencing this as well on multi-hour trips this week for Thanksgiving. Heat working fine for a while. Then the airflow seems to almost stop. After supercharging it works again. Did you ever take your car in for a fix or are you just working around the issue?