MobileClimate
Member
This is on a 105F ambient full cook with r-1234y which has a higher pressure than r134a. Don’t you have a 2016 with r134a?
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
AC Compressor theory of operation?
- Thread starter geordi
- Start date
MobileClimate
Member
Did you make sure to put in service mode when evacuating the system ? the chiller solnoid for the battery needs to be open ..if not there would be air in the system and which would cause high discharge temp and would cause intermittent operation of the system and sensors
There shouldn't be "air" in the system because it was never completely open even when changing the sensors. I evacuated it to nearly zero but just above, so that when I replaced the sensors it still had some pressure to prevent anything entering.
But I also had it on vacuum for 30 minutes, pulling from both the high and low sides simultaneously. I wouldn't expect any solenoids to be 100% positive seal but that is a new idea I hadn't thought about.
Does it have to be in anything other than basic service mode from the main screen? I don't have toolbox.
brainhouston
Active Member
I charged mine without service mode n system was open for 3 month.
Zero issues, been driving for a year already.
MobileClimate
Member
It says right in the service manual
HVAC system service mode
The vehicle uses two separate circuits, one circuit for the evaporator situated in the HVAC assembly for the cabin environment, and an additional circuit for the battery heat exchanger.
Both of these circuits have solenoid valves controlled by the thermal controller module. During A/C evacuation and recharge it is important to open these solenoids manually (service mode). This will ensure that all refrigerant is removed and replaced from both circuits during evacuating and recharge of the system.
Warning: HVAC service mode must be initiated using Toolbox before any evacuation and recharge procedures are performed. Refer to Service Manual procedure 18200102.
With the vehicle in service mode, the refrigerant can be recovered or recharged. The HVAC system will stay in service mode until the mode is exited using Toolbox or the laptop is disconnected from the vehicle.
Warning: It is important that the key remains in the vehicle during evacuation or recharge. If it is removed, service mode will be disabled, thus closing the solenoids, which means that there is a risk that the HVAC lines may not be fully evacuated or filled during recharge.
This can be done without toolbox just go to service mode
HVAC system service mode
The vehicle uses two separate circuits, one circuit for the evaporator situated in the HVAC assembly for the cabin environment, and an additional circuit for the battery heat exchanger.
Both of these circuits have solenoid valves controlled by the thermal controller module. During A/C evacuation and recharge it is important to open these solenoids manually (service mode). This will ensure that all refrigerant is removed and replaced from both circuits during evacuating and recharge of the system.
Warning: HVAC service mode must be initiated using Toolbox before any evacuation and recharge procedures are performed. Refer to Service Manual procedure 18200102.
With the vehicle in service mode, the refrigerant can be recovered or recharged. The HVAC system will stay in service mode until the mode is exited using Toolbox or the laptop is disconnected from the vehicle.
Warning: It is important that the key remains in the vehicle during evacuation or recharge. If it is removed, service mode will be disabled, thus closing the solenoids, which means that there is a risk that the HVAC lines may not be fully evacuated or filled during recharge.
I don’t think the basic service mode works that way, it did not show pressure climbing on the low side as I was charging the high side with the AC disabled and the computer on in service mode.
But there is no air in the system if you are pulling a vacuum on both sides before you start charging it. I had both valves open on my gauge set when pulling the vacuum and got to 30 inches. Left it there for about 20 minutes.
I started charging it only on the high side and did not see anything climbing on the low side until I turned the AC system on.
The image is what I’m reading on the gauges now while supercharging, considerably less power being drawn by the compressor than it was when I was supercharging a couple of days ago. The evaporator is maintaining at 36 degrees like you said it would.
Looks like it was the compressor, and hopefully the power usage is a lot lower - I won’t know for sure for a bit, because my next trip is going to be towing a 5 x 10 enclosed trailer filled with tools and boxes, so the range is definitely going to be tragic.
But there is no air in the system if you are pulling a vacuum on both sides before you start charging it. I had both valves open on my gauge set when pulling the vacuum and got to 30 inches. Left it there for about 20 minutes.
I started charging it only on the high side and did not see anything climbing on the low side until I turned the AC system on.
The image is what I’m reading on the gauges now while supercharging, considerably less power being drawn by the compressor than it was when I was supercharging a couple of days ago. The evaporator is maintaining at 36 degrees like you said it would.
Looks like it was the compressor, and hopefully the power usage is a lot lower - I won’t know for sure for a bit, because my next trip is going to be towing a 5 x 10 enclosed trailer filled with tools and boxes, so the range is definitely going to be tragic.
That's pretty much where my range has been for the last 6k miles at least. I've been hovering around 500 wh/mi on the highway whether I have had tool boxes on the back, or a flat open trailer... Or nothing at all.
Max range has been 130 miles on a FULL charge. This is why I've been trying to chase this power issue, b/c it makes no sense. The battery claims (Tessie) only 15% degradation, and 180 "real world" miles to 220 claimed by the car. But actual is 50 under that. YUCK.
Max range has been 130 miles on a FULL charge. This is why I've been trying to chase this power issue, b/c it makes no sense. The battery claims (Tessie) only 15% degradation, and 180 "real world" miles to 220 claimed by the car. But actual is 50 under that. YUCK.
brainhouston
Active Member
U can live by the book its ur choice
A lot of ppl worked on Tesla cars DIY style before that manual was made public or before geofence was removed from service mode
I don't see any AC threads claiming charging never worked unless u open those valves
Many things in official service manual are unnecessarily or can be bypassed or done differently from my experience...
Yeah, that procedure to replace the compressor for one - I didn't remove the coolant bottle, the air suspension reservoir, OR the coolant itself.
Only removed the wheel liner from the passenger side to finally figure out where the "forward junction box" is - because it isn't listed on any procedure of where the damn thing is located!
But I was able to pull the three bolts from the compressor and then just rotate it slightly in two directions and pull it out from under the coolant tank.
What needs a procedure (or a new design!) is that stupid desiccant bag and cap. They didn't put ANY lube on it when it was installed, so the plastic cap somehow ended up glued to the aluminum tube. I had to use a TORCH to melt it and get it moving before finally driving a screw through it to get it out. I wiped some aluminum anti-seize on the rings before I installed the new cap with the new bag and snap ring.
If brute force isn't working... You aren't using enough.
I recently did the same compressor change using the same procedure. I also ran into the same issue with the dessicant bag except that I ended up getting so fed up with it I replaced the entire condenser (it was cheap from Amazon).
However, I could use your advice on filling the r134a ('16 P90D MX) - I used a Vevor vacuum/manifold from amazon.
- I vacuumed for 40 min made sure no leak (with vehicle off and in service mode but not toolbox), then set the manifold high and low knobs to "closed"
- then I turned vehicle on, put it in service mode with a/c turned on with fan set to 2, attached a can of r134a.
- screwed the tap on the r134a can (attached to yellow hose of the manifold) and used the bleed valve to remove the air in the hose.
- once the window on the manifold showed some freon in it I then slowly opened the blue knob on the manifold (low) to fill the system. First can went through pretty easily however ac compressor has not kicked in.
- first can ran out, closed blue knob, detached first can, attached 2nd can and tapped it bled it and attempted to open the blue knob but this time i'm not seeing refrigerant move into the system
What might I be doing wrong?
At least you have the proper gauge set that reads both sides. This isn't rocket science and you don't actually need service mode for it. Your pressures though show that you don't have anywhere close to enough gas in it - which makes sense if you only got one can into a system that needs 3.
The compressor has multiple loops (three of them) that each have their own expansion valve AND can close themselves off. But luckily the system is open on the suction side so the valves only work to stop the flow, not eliminate it completely.
Since you have one can in right now, that's good for a start. Was your compressor pre-charged with oil? IIRC mine was, I don't recall adding any oil to it.
You don't need to worry about wasting gas by purging the hoses, but it's up to you if you want to do that anyway. The volume isn't large enough to make any kind of difference, the vacuum suction stage is WAY more important but it sounds like you got that right.
So to do this: You want to hold the can upside down and above the level of the gauges, so that everything flows downhill as much as possible. Have the system OFF before you start this, warm up the can in your hands or with a hot towel to get the refrigerant generating some pressure. It will push itself into the system at least to start. Get it charging for a few seconds to bring up the pressure a bit more then have a friend power up the car with the AC on LO and MAXIMUM fans. That will kick it into overdrive and with the can open to the low side, you should see the pressure drop while the high side starts climbing. When that can finishes off and you can feel it empty, just shut the fill valve and quickly swap to the next can, and open it right up again, upside down. That should get you everything into the car without needing to do any magic and by that point the system should be staying on. If the low side pressure drops below 30 too much the system will be in danger of freezing up (low gas) so you want to see pressures around 35-40 IIRC and high side should be around 150-200 ish depending on ambient temps.
The compressor has multiple loops (three of them) that each have their own expansion valve AND can close themselves off. But luckily the system is open on the suction side so the valves only work to stop the flow, not eliminate it completely.
Since you have one can in right now, that's good for a start. Was your compressor pre-charged with oil? IIRC mine was, I don't recall adding any oil to it.
You don't need to worry about wasting gas by purging the hoses, but it's up to you if you want to do that anyway. The volume isn't large enough to make any kind of difference, the vacuum suction stage is WAY more important but it sounds like you got that right.
So to do this: You want to hold the can upside down and above the level of the gauges, so that everything flows downhill as much as possible. Have the system OFF before you start this, warm up the can in your hands or with a hot towel to get the refrigerant generating some pressure. It will push itself into the system at least to start. Get it charging for a few seconds to bring up the pressure a bit more then have a friend power up the car with the AC on LO and MAXIMUM fans. That will kick it into overdrive and with the can open to the low side, you should see the pressure drop while the high side starts climbing. When that can finishes off and you can feel it empty, just shut the fill valve and quickly swap to the next can, and open it right up again, upside down. That should get you everything into the car without needing to do any magic and by that point the system should be staying on. If the low side pressure drops below 30 too much the system will be in danger of freezing up (low gas) so you want to see pressures around 35-40 IIRC and high side should be around 150-200 ish depending on ambient temps.
I gave it another shot and fans and ac at full blast I was able to get it to suck in an additional (320g) can of refrigerant after a LOT of shaking, positioning, begging and cursing it took a long time too about 15 minutes. However 3rd can it only took a tiny bit no matter what I did I can definitely feel the difference now the air is much colder (aprox 45F on a thermometer in the vent). The manifold gauge now reads about 70 at the low side and almost 100 on the high side.
I bought one of these to see if it does anything different to force the refrigerant in, but no luck after holding the trigger for over 10 minutes its built in gauge keeps showing "low" and doesn't budge which means its likely not able to put any in. I wonder what it is that I'm doing wrong.
brainhouston
Active Member
u need to be careful with amounts
i believe 5 seater X only has front AC n uses much less, follow ur sticker under hood...
Brain is right - go with the amounts from the sticker under the frunk lid. I have a 7 pass X, which has the dual systems (it's actually just an additional refrigerant loop from the discharge side with a second evaporator in the rear body) so if you have a 5 pass, then it won't take as much.
Trust the air temps though, the pressure feels like it might be a bit high, but these have multiple programs that they can run. It varies the pressure and the load as the temperature demand calls for.
What does the sticker say for your car's refrigerant charge amount?
Right I have a 6 seater it should take 920-1000grams which would’ve been 3 cans of 320grams. I only got 2 cans in so far.
Hmm… I didn’t have anything like this difficulty in charging my system. What was the reason you changed the compressor in the first place? I had thought I was having power consumption issues with mine and it turned out that it was working just fine….
I just wonder if you got some sort of blockage in the system because the low side pressure should be lower if it is not overcharged. Something doesn’t add up.
I just wonder if you got some sort of blockage in the system because the low side pressure should be lower if it is not overcharged. Something doesn’t add up.
It was a compressor failure and we did do a flush. Well the ac seems to still be working well now so I guess I’ll just take it for what it’s worth. I’m going to be doing this again in my other MX preemptively before it’s compressor goes out to save myself the trouble of a flush and condenser replacement.
Last edited:
