AC Desiccant Bag replacement service cost

[kpanda17]

Just to be clear, a majority of Tesla owners don’t experience this

My bud has a 5 year old M3 without any smell
He never changed the air filters
Although my experience is short, two Ts no smell

I would not say it’s a design flaw
There are environmental/location and use uniquenesses causing the issue

We need to find out what the pattern is
The design flaw is not being able to combat these uniquenesses

 

[afadeev]

Just spoke with an engineer from Mahle. The problem with the Tesla and, I guess, all electric vehicles is moisture getting into the system. The recharge oil, the materials that are used in the system and the design of the compressor all contribute to this and apparently it is a major problem that they are dealing with.

Why would that be the case?
I see no logical reason why EV AC system would be more susceptible to moisture ingress than that of any other vehicle. You?

I recently found out that they recommend changing the desiccant every 2 years. One of the major moisture leaks is actually through the stator.

Who is "they"?
Sources?

 

[ATPMSD]

I see no logical reason why EV AC system would be more susceptible to moisture ingress than that of any other vehicle. You?

Good question. I found this article:

Electric Vehicle Maintenance: A/C Desiccant Replacement

Electric Vehicle Maintenance: A/C Desiccant Replacement What is a desiccant bag? A desiccant is a hygroscopic substance, meaning it absorbs water. Think of those silica pouches inside a shoe box; the ones that say “do not eat” on them. They’re a desiccant and used to prevent moisture build-up...

mygarageairdrie.ca

 

[dusty22]

How does all of this relate to the newer cars that use a heat pump?

 

[MP3Mike]

How does all of this relate to the newer cars that use a heat pump?

The heat pump systems still have a desiccant bag that Tesla says needs to be replaced occasionaly.

 

[ATPMSD]

How does all of this relate to the newer cars that use a heat pump?

A Heat Pump is an AC system that can also produce heat. A home Heat Pump system is an AC system that can in run reverse. The Heat Pump in Tesla cars is much more sophisticated, of course.

 

[zroger73]

Just spoke with an engineer from Mahle. The problem with the Tesla and, I guess, all electric vehicles is moisture getting into the system. The recharge oil, the materials that are used in the system and the design of the compressor all contribute to this and apparently it is a major problem that they are dealing with. I recently found out that they recommend changing the desiccant every 2 years. One of the major moisture leaks is actually through the stator.

Either you or that engineer is lying or they need to go back to engineering school.

The entire refrigerant system always has positive pressure - refrigerant and oil can leak out, but water can't leak in unless there was a leak AND a failure that resulted in negative pressure (vacuum) at the location of that leak, but, if that was the case, you'd have reduced or no HVAC performance regardless of whether or not the desiccant bag was due for replacement.

The stator is inside the compressor housing. Refrigerant flows over the stator for cooling.

 

[thefrog1394]

Just got an estimate for A/C service (desiccant bag replacement) from Tesla service in St Louis for $367.50 (before tax). Seems reasonable given what the service is.

Just some other comments after reading through this thread:

THIS SERVICE HAS NOTHING TO DO WITH THE SMELLY A/C ISSUE! It's been reiterated a few times, but it seems people are still getting confused. This is related to moisture in the A/C refrigerant system, which is closed, and not at all possible to be related to your air filter getting leaves and junk in it which causes the smell.

Either you or that engineer is lying or they need to go back to engineering school.

The entire refrigerant system always has positive pressure - refrigerant and oil can leak out, but water can't leak in unless there was a leak AND a failure that resulted in negative pressure (vacuum) at the location of that leak, but, if that was the case, you'd have reduced or no HVAC performance regardless of whether or not the desiccant bag was due for replacement.

The stator is inside the compressor housing. Refrigerant flows over the stator for cooling.

I admit I don't really understand the physics behind how moisture might enter the positively pressurized refrigerant system, but clearly it is possible or else there'd be no need for desiccant in the system at all. We are talking about extremely small amounts of moisture that can cause issues here though.

 

[brkaus]

Just got an estimate for A/C service (desiccant bag replacement) from Tesla service in St Louis for $367.50 (before tax). Seems reasonable given what the service is.

View attachment 1026814


Just some other comments after reading through this thread:

THIS SERVICE HAS NOTHING TO DO WITH THE SMELLY A/C ISSUE! It's been reiterated a few times, but it seems people are still getting confused. This is related to moisture in the A/C refrigerant system, which is closed, and not at all possible to be related to your air filter getting leaves and junk in it which causes the smell.



I admit I don't really understand the physics behind how moisture might enter the positively pressurized refrigerant system, but clearly it is possible or else there'd be no need for desiccant in the system at all. We are talking about extremely small amounts of moisture that can cause issues here though.

I believe the theory is moisture is in the system initially. Impossible to get all out. Desiccant gets that moisture out. However, over time the desiccant breaks down and can also cause problems.

 

[thefrog1394]

I believe the theory is moisture is in the system initially. Impossible to get all out. Desiccant gets that moisture out. However, over time the desiccant breaks down and can also cause problems.

Hmm, maybe incompatibility with the oil used in electric compressors then causing an issue? I don't get why they would function differently than your standard automotive A/C compressor. I also wonder if the difference is just that with A/C being an essential part of the drivetrain now effectively due to battery cooling, if the risks are similar, but there's a higher standard for reliability/longevity than with ICE vehicles. This wouldn't explain the odd differences in replacement interval between Tesla vehicles though.

I will say this though to those suggesting this maintenance isn't actually needed: engineers don't typically decide to recommend a new service like this as a maintenance item for no reason. The best service is no service. Tesla doesn't list things like coolant changes or differential oil changes that some other manufacturers do, so they clearly don't have a pattern of recommending unnecessary services. Just because we don't understand the mechanism behind it doesn't mean there isn't one. I'm inclined to play it safe and pay the 400 bucks here. A/C compressor replacement costs almost as much as a drive unit at $3,500.

 

[zroger73]

Hmm, maybe incompatibility with the oil used in electric compressors then causing an issue? I don't get why they would function differently than your standard automotive A/C compressor. I also wonder if the difference is just that with A/C being an essential part of the drivetrain now effectively due to battery cooling, if the risks are similar, but there's a higher standard for reliability/longevity than with ICE vehicles. This wouldn't explain the odd differences in replacement interval between Tesla vehicles though.

Standard automotive A/C compressors are only used for cooling and dehumidification of the cabin - they are not used for moving heat between other components such as batteries and electric motors or heating the cabin. They also cycle on and off using an external electromagnetic clutch to constantly maintain the evaporator just above freezing instead of running continuously. In other words, the refrigerant system in a Tesla works much harder and more frequently than it does in a gasoline-powered vehicle. Also, some gasoline-only vehicles specify desiccant replacement as well, thought (understandably), not as frequently as Tesla.

 

[thefrog1394]

Standard automotive A/C compressors are only used for cooling and dehumidification of the cabin - they are not used for moving heat between other components such as batteries and electric motors or heating the cabin. They also cycle on and off using an external electromagnetic clutch to constantly maintain the evaporator just above freezing instead of running continuously. In other words, the refrigerant system in a Tesla works much harder and more frequently than it does in a gasoline-powered vehicle. Also, some gasoline-only vehicles specify desiccant replacement as well, thought (understandably), not as frequently as Tesla.

Less frequent use would definitely explain 6 yrs for non-heatpump Model 3 vs 4 years for those with heatpump.

Doing some googling and there's quite a few theads with folks questioning why this is required, but few answers. It's just a matter of time until an engineer who works on one of these systems comes across one of these threads and fills us in. Maybe I'll try and find an appropriate Tesla engineer to Xeet at and see if they respond haha

 

[thefrog1394]

Ok I asked the Cybertruck lead engineer and vehicle reliability lead for all Teslas on X. Go like my tweet and maybe we’ll get a response!

https://twitter.com/x/status/1767427588631236745

 

[zroger73]

There are some ICEVs that specify desiccant bag replacement...

Why does Tesla recommend replacing the A/C dessicant bag as a maintenance item?

I was very surprised to learn that Tesla recommends replacing the "A/C dessicant bag" every 2-6 years (depending on year and model) as a maintenance item. I understand the purpose of dessicant in a refrigeration system, but once the dessicant absorbs any moisture that may remain in the system...

teslamotorsclub.com

 

[TomT]

I have never heard of a service requirement like this. The AC refrigerant loop is sealed. The desiccant should only need to be changed if the loop is opened for service or broken in an accident.

Agreed. Unless there is a leak or damage, it should never need to be replaced.

 

[zroger73]

For the last few decades, I have traded for a new vehicle every year on average. As long as that trend continues, desiccant replacement will be non-issue for me. However, if I choose or am forced to keep my Model Y longer than 4 years, I will have the desiccant bag replaced per Tesla's maintenance schedule.

While I worked on automotive air conditioning systems for decades, I had never heard of desiccant replacement except when a system was left open to atmosphere or some other abnormal condition occurred such as a catastrophic compressor failure or contamination issue (e.g., wrong oil installed).

I also never worked on heat pumps or thermal management systems on hybrids or EVs. The refrigerant systems on those type of vehicles tend to see much greater duty.

I'm learning that desiccant replacement isn't about absorbing moisture, but about the desiccant breaking down with time and use and eventually contaminating the system. Keep in mind Teslas use a variable-speed scroll compressor with integrated electric motor instead of an engine-driven piston compressor and have a much more complex refrigerant circuit with many more solenoid valves and electronically-controlled orifices to direct and control the flow of refrigerant compared to most other motor vehicle air conditioning systems.

 

[MP3Mike]

Agreed. Unless there is a leak or damage, it should never need to be replaced.

I've seen where it was said that over time, and from vibration, that the desiccant breaks down and can pass through the filter sock it is inside and contaminating the system and possibly clogging orifices. (But that would seem more like a mileage based thing instead of the time based period that Tesla, and other OEMs have given it.)

 

[Andrew*Debbie]

Hmm, maybe incompatibility with the oil used in electric compressors then causing an issue? I don't get why they would function differently than your standard automotive A/C compressor.

Water in the refrigerant loop is bad. It will mix with the oil and make sludge. That could or will lead to very expensive repairs.

Agreed. Unless there is a leak or damage, it should never need to be replaced.

It should be a closed system.

Tesla aren't the only ones recommending occasional replacement. Presumably either a small amount of moisture gets in past the seals or it can break down with age. No idea.

 

[zroger73]

I've seen where it was said that over time, and from vibration, that the desiccant breaks down and can pass through the filter sock it is inside and contaminating the system and possibly clogging orifices. (But that would seem more like a mileage based thing instead of the time based period that Tesla, and other OEMs have given it.)

With that said, keep in mind that the heat pump in a Tesla is also used to heat or cool the battery while fast charging, for Cabin Overheat Protection, and when Camp/Dog/Keep Modes are in use.

I drive about an hour per day, but I spend about 1.5 hours charging at free-to-me locations during which time the heat pump is running to keep the cabin comfortable. So, in my case, my heat pump spends more time operating when the vehicle is NOT being driven than when it IS being driven.

If a person uses Camp Mode overnight once per week in their Tesla, they are probably also using the heat pump more while parked than while driving.

Tesla's time-based recommendations for desiccant replacement could be "worst-case scenarios" with the assumption that a person will spend a lot of time using the heat pump while parked and/or it could be that the desiccant tends to break down more with time than with use or in addition to use.

If Tesla said to replace the desiccant every 50,000 miles instead of 4 years, that won't account for variable uses such as owners who never use their climate control when they're not driving compared to those who live in their Teslas (extreme example, but there are people who do it), either.

Speaking of that example linked above, I suspect his Tesla heat pump sees extreme duty - possibly as much as 24 hours a day. If the desiccant breaks down with use, he should probably be replacing it every 3-6 months!

And, that leads to another question... If a person lives in their Tesla and uses the climate control 24 hours per day and the desiccant broke down and ruined expansion valves and the compressor and the Supermanifold within the 4/50 warranty period, will Tesla cover the damage? I mean - I don't believe their warranty specifies limits on how much time you can spend using Camp Mode.

 

[zroger73]

Presumably either a small amount of moisture gets in past the seals...

That simply can't happen. The sealed part of the refrigerant system is under pressure with respect to atmosphere - even the low/suction side. In order for moisture to get past the seals and enter the system, you'd have to put the entire vehicle in a giant pressure vessel or submerge it under hundreds of feet of water.