Air conditioning cycles to warm? Normal?

[buttershrimp]

Hey folks. Currently on a 1200 mile epic journey home from Florida to Ohio. It’s pretty toasty down here as you may imagine. Have had the air con pretty much running non stop. Every 10-15 minutes the AC condenser seems to cycle off for about 45-60 seconds. Then comes right back on. With no user input.

Driving in range mode. Roadster 613 2.0 with r80 upgrade. New car to me. 4500 miles young.

Is this behavior normal? When condenser is on we get super cold and comfy temps. So maybe his is a function of range mode? Or just the condenser not wanting to overheat?

I had my AC start to struggle after running nonstop in Texas a week or two ago, it happened twice, both times long days and was in camper mode for a long time and then it was like it was muffled or something..... Anyway, was in for service last week, and they pulled the logs.... get this.... it is apparently too good..... ice built up on the compressor or something and restricted flow.... was told that they are working on a firmware update for this. It took a long time, at least 5 hours of driving and running while in park, in 100+ degree weather

Pretty interesting huh?

 

[gregd]

I had my AC start to struggle after running nonstop in Texas a week or two ago, it happened twice, both times long days and was in camper mode for a long time and then it was like it was muffled or something..... Anyway, was in for service last week, and they pulled the logs.... get this.... it is apparently too good..... ice built up on the compressor or something and restricted flow.... was told that they are working on a firmware update for this. It took a long time, at least 5 hours of driving and running while in park, in 100+ degree weather

Pretty interesting huh?

Interesting theory, but not applicable for a Roadster (no camper mode, for starters). Also, the evaporator inside the ESS can't freeze, given that it's bathed in the hot battery coolant, and that's the one I care about.

 

[buttershrimp]

Interesting theory, but not applicable for a Roadster (no camper mode, for starters). Also, the evaporator inside the ESS can't freeze, given that it's bathed in the hot battery coolant, and that's the one I care about.

Oh, I'm sorry, I don't read before I post. It's something I'm working on.

 

[gregd]

They probably needed to add more refrigerant for the battery cooling, and changed the amount to 800g. The 2.0 I have was salvaged with 1500 mi and has never been serviced, so the sticker shows 720g. 40C (104F) outside is really hot, and the 22.6 bar is towards the very top of acceptable at that temp, but as long as it does not overheat and shut down you should be OK. Check it when the outside temp is at around 90F (32C), and it should be a lot lower. You really need to check it while driving, as those little fans and stagnant garage air will mess with the pressures.

Yeah, could have been a change during production. I checked the user manual, and as you noted it says 725g, but they probably aren't quite so careful to keep that up to date with the particular car it rides in.

The picture I took during today's at-home charging was in the garage, and it was no where near 104 in there. Probably in the upper 80's, to low 90's. Not sure why the car thought differently. One other thing I noticed is that the RPMs seem lower today than before, which I think (hope?) is good. More efficient, so lower heat buildup? Pseudo-science, perhaps.

At this point I'm giving them the benefit of the doubt that they did it right, but will chat with the service manager when he calls, just to close the loop on things. With the changes to the fascia pieces by the prior owner, perhaps by some chance the piece with the label on it might have gotten swapped too? Long shot, but as was stated earlier in the thread, the HVAC system is critical to battery health, so I want to be sure. Thanks for your help!

 

[gregd]

The 2.0 I have was salvaged with 1500 mi and has never been serviced, so the sticker shows 720g.

For the historical timeline, what VIN is the car? I'm wondering if there was a cut-over VIN between the 720g (or is it 725g as documented in the user guide?) and 800g as my car seems to think it should be... Mine is #834.

 

[ML Auto]

I'll just say its just a week or two after yours. Very close, but after.

 

[gregd]

I'll just say its just a week or two after yours. Very close, but after.

Ok, that's potentially significant, thanks. The manager never called (at least not yet), so I'll follow up next week...

 

[ML Auto]

Ok, that's potentially significant, thanks. The manager never called (at least not yet), so I'll follow up next week...

I drove my 2.5 about 100 mi in 95 degree heat this weekend and my high pressure stayed just under 12bar the whole time. So I think your system still has too much refrigerant. I know mine has exactly 800g in it because it was completely empty for months before I recharged it. I doubt Tesla evacuated your entire system and refilled it with 800g-that would take hours to do properly. They probably just let some out. Did you peek at the condenser to make sure its clean?

 

[gregd]

I drove my 2.5 about 100 mi in 95 degree heat this weekend and my high pressure stayed just under 12bar the whole time. So I think your system still has too much refrigerant. I know mine has exactly 800g in it because it was completely empty for months before I recharged it. I doubt Tesla evacuated your entire system and refilled it with 800g-that would take hours to do properly. They probably just let some out. Did you peek at the condenser to make sure its clean?

Yep, the condenser is clean. Also, I don't know when they actually did the evacuation procedure, and the repair order does specifically say that they emptied it and re-filled, so I have no evidence to the contrary.

But, some education for me if you could... Your 12bar pressure was during a drive, and my 22 bar was during charging. The HVAC screen showed that the system was calling for 100% cooling during the charge cycle. I haven't experimented with it, but doesn't the normal cabin cooling call for something less than 100%? If so, I would think the pressure would drop too...

Still no manager call (haven't bugged them yet, as I was busy on other things this past week). My questions to him will be to confirm what the pressures should be (numbers, not that they were "fine"), and when were they tested. I specifically asked that they charge the car after the work was done, and during that charge to verify the pressure was correct. All I know is that they did charge it. This was after telling me that they couldn't because they didn't have a compatible EVSE, so I pointed them to the CAN-SR in the trunk. Nice 70 amp charge, with a starting battery temp about 41C, ending in the low 30's, if I recall, and no alerts generated. But the HVAC compressor had surely cooled down by then, even after the high speed run up and down the freeway.

 

[dgh]

A bit off topic, but was wondering is 1.5 owners can comment on how cold the A/C should be.

Roadster is rarely driven, but last year, the PEM was dead and had to be replaced. The service center noted that the compressor was bad, and I put off the repair until last week. I don't recall ever using the A/C before, so I don't have a benchmark for how cold it should be.

Anyway, on a day that was 75 degrees (24c) and muggy, I turned the A/C on the 20 minutes drive home from the service center. It definitely worked, but it was not very cold. From past experience driving ICE cars, I really the A/C being very cold, especially after the refrigerant was just charged.

I called the service center, and they are agreeable of course to check it out, but I was wondering if I could get some comments from other Roadster (esp. 1.5) owners on if a properly working A/C blows cold air, or only makes a meager effort. I know that the battery gets priority over the cabin, but I would think on a short drive the cabin would have been chillier.

 

[DrComputer]

The A/C in the 1.5's never worked very well. It was one of the major changes they made when they went to the 2.0. It's a completely different HVAC system. The 2.0 still suffers the problem that the coolant can either be routed to the cabin or battery, but not both at the same time.

 

[backmost]

I have a 1.5 and the AC is very cold, but I'm always cold lol

 

[gregd]

My 2.0's A/C can be relatively cold, but I think the ICEs that I've owned have been colder.

Two comments, however. First, the A/C system isn't just for your comfort. It's also a key part of the battery management system, both during charging and while driving. If the battery gets too warm while driving, the A/C will kick in to cool it down. During charging, especially on a Range charge, it pulls heat out of the battery both to keep it cool, and because a cooler battery can safely store more energy. So, it's important to keep the A/C system healthy, not just for you, but also for the battery and charging system's proper operation.

Second, as noted earlier, if the A/C is needed for the battery while driving, it will steal most of the cooling from the cabin. This typically lasts only a few minutes, and you will hear a soft "click" when it engages and the cabin will begin to warm a bit. My understanding is that it's not taking 100% of the cabin cooling for the battery, but pretty much most of it. If the battery needs cooling when you don't have the cabin A/C on, you will still feel a bit of cooling in the cabin. That demonstrates to me that the two systems are definitely linked. Cabin is always being cooled when the A/C is on, with the battery side only as necessary.

Greg

p.s To close on my earlier comments about the pressures, I never did get a call back from the service department manager. My car just started urping up 1146 alerts (unrelated to the A/C system), so it looks like the car may be headed back to the shop. Will have my discussion with them at that time.

 

[slcasner]

The A/C in my 1.5 is plenty cold. When using the A/C I normally turn the temperature knob all the way to the warm end of the scale because otherwise it is too cold on my hands on the steering wheel. I'm located in relatively dry California, though, not muggy East Coast.

 

[DeedWest]

A bit off topic, but was wondering is 1.5 owners can comment on how cold the A/C should be.

Roadster is rarely driven, but last year, the PEM was dead and had to be replaced. The service center noted that the compressor was bad, and I put off the repair until last week. I don't recall ever using the A/C before, so I don't have a benchmark for how cold it should be.

Anyway, on a day that was 75 degrees (24c) and muggy, I turned the A/C on the 20 minutes drive home from the service center. It definitely worked, but it was not very cold. From past experience driving ICE cars, I really the A/C being very cold, especially after the refrigerant was just charged.

I called the service center, and they are agreeable of course to check it out, but I was wondering if I could get some comments from other Roadster (esp. 1.5) owners on if a properly working A/C blows cold air, or only makes a meager effort. I know that the battery gets priority over the cabin, but I would think on a short drive the cabin would have been chillier.

I just drove my friend's 1.5 last week. When I got into the car, the battery was at 39C from sitting in a Texas garage in the Texas heat. Go figure. I started the car, and watched as the A/C was routed directly to the battery & the temperature gradually dropped. What intrigued me, however, is that the car CONTINUED to cool the battery...all the way down to 31C and seemed to keep going.

At that point, I'd been driving (and it continued to drop WHILE driving) and reached my destination, so I didn't give myself the chance to sit and watch what eventually happened. So far, this is our only theory why his A/C has "never really worked that well". Could it be a firmware issue? Could this car potentially not realize when it's done cycling A/C to the battery and be unable to switch back to cabin? Does this car care so much about its own battery that it doesn't want to give us A/C?
(which would be hilariously ironic, as the CAC value is pretty mediocre)

I've driven numerous 2.0's and 2.5's and their thresholds are all the same. When battery gets to 41C, A/C gets stolen and it cools down to 38C before returning to the cabin. This repeats as necessary while driving.

 

[DrComputer]

There were several iterations of the firmware where they tweaked the thresholds of when to switch between cabin and battery cooling. Possibly your friend with the 1.5 never got updated to the latest firmware that addressed the issue.

 

[DeedWest]

Ironically, now my 2.0 is experiencing some spooky issues with the HVAC system.

Yesterday evening, the car was charging. It was in the middle of a battery cooling cycle & the fans were running successfully. I manually stopped the charge, put my cable away, and got into the car to start it, while instinctively pressing the A/C button as I usually do. I hear the distinctive "click" but the compressor does not turn on. Tried it several times...even tried resetting via open/closing the charge port door several times. Nothing.

Here's what my HVAC screen in the diagnostic menu was saying last night while charging. I limited it to 16A to prevent heating it up too much further.

I'm about to check it out this morning and see what it's looking like now. Any suggestions?

My guess is based on the information provided by @MLAUTO earlier in this thread, it could either be the evaporator clogged or the compressor shutting down due to to the evaporator temperature getting too low. Yesterday was extremely hot and the car WAS charging outdoors in the sunlight...so I'm wondering if this was a preventative measure.

 

[gregd]

Could also be that the compressor got too hot. I had that happen on a return trip in the heat. Similar battery temps. But in my case, it did cycle on; just didn't stay there.

 

[ICON]

My A/C doesn't seem to cool the cabin as effectively as it did before and the cabin temperature looks like this after the 35 minute morning commute.
It wouldn't drop below 27'C and outside was 37'C off the road surface.
Car A/C was in recirculate and all dials turned to Max ~ I was not driving above 69 Kph and all the battery, pem and motor levels were in the blue zone.
Is 26-27 C normal ? Or should it drop below.
Do these numbers look odd?
Thanks

 

[ML Auto]

Looks like the refrigerant is low and need a recharge. 9.3 bar is really low for 37'C outside temp.