HVAC not cooling!

[Rotarypower]

Need some help from my roadster friends!

Have a 2011 roadster sport and bottom line the HVAC system is not cooling. So this is a big concern with the battery! I need to get this resolved ASAP as battery is sitting at 34-35 *C. The circ pump is working and running continuously. I went into the HVAC service mode and can confirm circ pump turns on and off, and both solenoids can be activated and deactivated.

Yesterday I was in the service screens and confirmed air out T of the hvac system was same T as ambient. The compressor spins up fine and shows it is running on the service screen. Freon pressures register around 2-3 bar when sitting idle and between 7-8 bar when the compressor spins up. Ambient here in Raleigh is running about 95*F.

I have searched and searched the forums but can’t seem to find details on what is normal and a strategy to troubleshoot this type issue. My best guess is I simply need to have the Freon charged. But I need to confirm what I am seeing is consistent with this being the problem.

Well the other issue is the Raleigh SC won’t support the car anymore. So not sure where to go to address any issues. I can’t evacuate or charge the hvac system myself.

To add insult to injury while exiting the service menu something happened and the VDS and VMS decided to hate each other and are no longer communicating (see other VMS thread I bumped today). This is a secondary issue I believe unrelated. Primary concern is to get the HVAC system working so I can charge the battery and keep it cool.

Right now I’ve reverted to using the CAN SR and my model3 mobile charger at 120V @12 amps in an attempt to minimize heat input into the ESS. I have battery at 102 ideal range but trying to get a little higher as I believe I’ll eventually need to pull the ESS disconnect to resolve the comms issue with the VDS and VMS as screen is devoid of any data (no battery range, can’t get into service menu, can’t do anything useful basically). Concern there is breaking the disconnect and then I’m unable to do anything until that is fixed (just thinking worse case here).

Luckily I have OVMS and am able to command charging from the app. What an invaluable add on …. Can’t imagine not having OVMS! Thank you @markwj !

Any and all help would be greatly appreciated!

 

[ML Auto]

You are low on refrigerant. Your pressures should be around 15 BAR when the compressor is on at that ambient temp.

35' C is nothing to worry about. Mid 40s and you can start to be alarmed.

 

[Rotarypower]

Hi @ML Auto ….. thank for the info. That is what I thought but just needed someone to confirm. If the Tesla SC won’t touch the car, where do you typically take for HVAC work? Something like a refrigerant recharge isn’t rocket science, however, I think most shops will be a little dubious about the car.

Is there a process for complete evacuation and proper recharge? The Tesla service manual is vague. Once in service mode, the 2 solenoids are operated by the a/c and recirc buttons, so does the light on mean they are open or closed? I assume evacuation and recharging should both be done with both valves open? Does blue light on indicate open (which I assume energized)? Even the Tesla Academy manual that has been passed around amongst us has no detail on this.

Any additional help would be appreciated!

 

[ML Auto]

Any shop that does A/C should be able to handle it. You don't need to worry about the service mode and the solenoids unless you are evacuating it. Since you still have pressure in the system, all you need is a recharge, unless they find a leak. There is a sight glass on the drier to determine when the system is full, which makes is easy to do for someone worried about working on the car. You could even buy a can or two of 134a and do it yourself. Fill it slowly until the bubbles in the sight glasss go away. Just make sure no oil, stop leak or "conditioner" is used.

 

[gregd]

Also be sure not to over-fill the A/C system. The Tesla SC put a little too much in one time, and a few months later during a long drive in hot weather the compressor over-temped, resulting in a very hot battery (to the point of being power limited). Unfortunately, the compressor overtemp alerts (#1463) don't get displayed on the VDS, so it wasn't until I got home and did some troubleshooting that I understood what had happened.

 

[Rotarypower]

Well here is an update. The battery temp remained at 35*C and I felt like I needed to do something. Well one thing is, I am able to get the Raleigh SC to take an appointment for the roadster which was a big surprise. However, the earliest available appointment is August 17. Arggg.

So, I decided to take matters into my own hands and today bought a small can (340g) or R134a refrigerant (no additives, just straight R134a). Bought a hose kit with pressure gauge. I put the entire can in the system. Not sure how much was left in the system when I started (750g is the target amount for a completely empty system) but with Toutside at 33*C ambient, TcabinOutlet was around 12*C. So definitely that was the issue. I am charging now in range mode and battery is now slowing cooling down. We will see if I can get it to 25*C.

With compressor running, Prefrigerant is anywhere from 9-10 bar for cabin a/c (12*C air) or 14-15 bar for battery cooling. The 15 bar number varies a lot so hard to pin down one target pressure whilst cooling the battery.

Obviously the best solution is to fully evacuate the system and simply put in the 750g of R134a then you know it’s the design target number. But, for a simple top off this is good for now.

Planning on keeping my appointment with Tesla as I should probably have a leak check performed. However, this may be the first time the car has needed refrigerant so perhaps this was a normal and expected leak down over time?

 

[X.l.r.8]

I personally would have an ac shop put some dye in and get a UV flashlight. No point having a refill if you have to do it again, there are a few parts that are unobtainable from Tesla that you will have to supply yourself. I suspect you have a leak from a connector or the condenser.

 

[ML Auto]

I personally would have an ac shop put some dye in and get a UV flashlight. No point having a refill if you have to do it again, there are a few parts that are unobtainable from Tesla that you will have to supply yourself. I suspect you have a leak from a connector or the condenser.

Absolutely not! The dyes are mixed with oil and probably not compatible with an electric compressor. Adding extra oil always reduces efficiency, and the system is already weak.

The best solution is not to evacuate and recharge the system, as you almost always lose a little oil when you take the refrigerant out. Tesla already changed the amount of 134A needed because they didn't get it right the first time. You just need to fill it until the high side always remains a liquid. Follow the small A/C lines to the drier (round canister about 3" in diameter) which has a 1/2 inch glass window (the sight glass) in the middle. Clean the glass and shine a flashlight on it with the A/C on high (best when the ESS is cooling and compressor at 100%) to see if the system is full. If you see bubbles it is still low. You need to constantly look at it for around a minute as the system circulates.

The correct pressures are dependent on outside/inside temps, humidity and airflow, but it looks like you are still a little low. 15 bar with just the cabin A/C on at 90 degree outside temp is normal. The fans go on high around then and then the pressure will start to drop. 9 to 10 bar is a little low.

Any shop can do a leak test with a sniffer. The Roadster is actually one of the easier cars to leak test because the entire system is accessible from under the hood. Do a quick look at all the fittings to see if any of them look like they are damp and dirty from seeping A/C oil.

I would make sure it is full and keep an eye on the sight glass every few days to see if any bubles appear. A big leak won't last a week. Small leaks can take months or years to get low. They happen when the system heats up and expands, and then cools down and contracts. The rubber o-rings get old and brittle and start to seep as the fittings expand. Usually when the system is running everything is hot and sealed tight, and you won't find a leak. You have to check it both cold and hot. That is why people resort to using dyes-they only check the system while hot and never find a leak.

 

[eHorses]

I need help figuring out what all this means. Ac is working but I’m trouble shooting to address any problems.

It looks like i have a bad ‘TcabinOutlet’ sensor (it’s reading 67C or around that all the time). I had the system checked and filled with last PM. Garage temp is about 26C. Attached are pre-charge picture and intra-charge picture with ‘Prefrigerant’ at 5.8bar and 18.8bar (>270psi, this seems really high), respectively. It’s only able to drop the ‘Tcoolant’ to high teens or low 20’s C where as I’ve seen other cars reach low teens.
PRE-CHARGE:

INTRA-CHARGE:

 

[ML Auto]

Your pressure seems a little high. Are the fans working at full speed? They start on low and then kick on high around 15bar. If they are fine check the condensor for road debris. Look through the grill on the bumper at the bottom of the condensor. You can back flush it from the top past the fans if it is dirty. If everything is OK then you could have too much refrigerant.

Your system is cooling-19C is about right with a 32C bat temp, mine kicks off around 18C. The bat temp takes a long time to go down.

The outlet temp sensor reading is off, but the system works without it. It could just be unplugged.

Are you having any specific problems with the A/C, or just checking things out?

 

[eHorses]

Your pressure seems a little high. Are the fans working at full speed? They start on low and then kick on high around 15bar. If they are fine check the condensor for road debris. Look through the grill on the bumper at the bottom of the condensor. You can back flush it from the top past the fans if it is dirty. If everything is OK then you could have too much refrigerant.

Your system is cooling-19C is about right with a 32C bat temp, mine kicks off around 18C. The bat temp takes a long time to go down.

The outlet temp sensor reading is off, but the system works without it. It could just be unplugged.

Are you having any specific problems with the A/C, or just checking things out?

Thanks for the tips! I’ll work on them.
The fans do run at variable speeds and faster at higher bar but I’ve notice cooling cycle’s seem to be shorter, especially when the pressure is 17-19bar. The system looks like it’s cutting short to protect from over pressure. Does it want to avoid going over 20-21bar (>300psi)???

One of my concerns was the system being over filled and producing longterm problems. How would I know?

What’s the function of the ‘TcabinOutlet’ and where is it located? Does it have anything to do with the blower? In the winter months, I’ve noticed that the vent blowers seem to have a low baseline output even when the HVAC is off. I’ve not notice that in other roadsters.

Thanks again for your help!