Potentially the longest thread in history...

[PP Mguire]

Any car AC specialists/experts here? I wanna know what makes modern car AC's much better than old cars' so I can (try to) apply it to my 1992. I'm looking for technical stuff, not generic use tints, park under shade, start at lower blower speed and such. It already uses r134a and it's factory fit so conversion is not needed.

More efficient compressor, bigger condenser, better insulating material for the inside. The last 2 are the big differences. My wife's vehicle is a 2020, and my truck is a 2021. My AC works way better than hers because my radiator and condenser are ginormous so hey don't get so heat soaked compared to hers.

 

[Smart_Guy]

More efficient compressor, bigger condenser, better insulating material for the inside. The last 2 are the big differences. My wife's vehicle is a 2020, and my truck is a 2021. My AC works way better than hers because my radiator and condenser are ginormous so hey don't get so heat soaked compared to hers.

The first two could be difficult to do because of how cramped it is under the hood. The compressor is a 17 (whatever unit) and is clutch driven. Any idea if other whatever-driven compressors modern cars have are better in cooling? Does insulating the pipes under the hood make a difference? I see they get cold and I can feel the heat from the engine around it. Thought about insulating them but dunno what material. Don't wanna have it catch fire from engine heat.

Would clean looking (no fins damage) condensers get bad internally that flushing and cleaning do not work anymore? This one is like 8 years old now. I feel degradation in cooling. Everything other than the condenser and the evaporator is now changed and a good cleaning and flush were done too.

 

[Joe C]

Actually, I always thought the older cars were better at cooling.
Old cars used R-12 refrigerant and when you turned the A/C on you got instant cold. Today's cars take some time to kick out the cold because R-134A is what they call a blend. That means there are two different types of a refrigerant chemicals that need to be mixed together in order to provide efficient cooling and that usually takes several minutes of running before you get any cool/cold air out of the cars A/C.

A very basic operation:
Your compressor pump moves the refrigerant through the system
It forces the liquid through what they call a TXV valve (thermal expansion valve) When the liquid refrigerant goes through a pressure drop caused by the TXV valve, it enters the Evaporator (the cooling coil inside of your car)This pressure drop from the TXV valve causes the liquid refrigerant to boil and (anything that boils will absorb the heat) This boiling action absorbs the heat of the air passing through the evaporator fins. This air is the air your cars fan pushes through the evap coil. The refrigerant vapor that absorbed the heat from the evap is drawn back to the compressor pump. From there the the compressor pump pushes it into a hot high pressure gas goes into the condenser coil (this looks like a radiator in front of the cars water cooling radiator) The hot gas gets cooled back to a low pressure liquid which starts to go back to the TXV valve and starts the cycle again. Of course the are several other parts that I am not mentioning because I'm keeping it simple to understand.

The condenser can get dirty from outside crap getting in the cooling fins, but usually you can hose that out if you provide access. I suppose it matters on where you live too because we just see much in the way of plugged up condensers around here. There sould only be refrigerant inside your condenser and that stuff won't damage the condenser so that it would need to be cleaned unless somebody put the wrong refrigerant in it and that would screw up more than the condenser. Just foam insulation on the pipes that are made for automotive grade.
A degration in cooling could be a multiple of things, This R-143A is two different refrigerants and separately they both have different boiling points so I suppose that if your system leaked and the blend was out of what it should be that could affect the cooling properties....but if you just all those parts replaced then you should have a fresh charge of new R-134A

 

[kmanmx]

My mom's Nissan can barely keep the car cool when it's 70f outside. My Volvo kept cool when it was 100f a couple weeks ago. To be honest I imagine the Nisssan's AC just needs some maintenance. But i've had brand new cars with markedly different AC performance. My Audi A4 was better than my A6, but my SEAT Leon beat both of them despite being the cheapest.

 

[Smart_Guy]

While new cars' AC's need more time to cool the refrigerant, they still get cooler in a relatively good time and reach lower temps. We did own two cars with r12 but they were used and old enough at the time that r134 came the norm already. They were 1986 both and owned mid 90's until mid 2k's before selling them, while at the time I drove other cars and they all had better AC's in general with their r134. The thing is, the cars we owned were known for their bad AC's. I suspect it's something in the system it self, be it pipe/hose distribution, specs of the AC parts, thermal sealants, or something, dunno. I'm trying to figure this out to do something about it. The AC is a separate system of its own in cars so something can possibly be done there. The 1989 Grand Marquis we had before had much better AC that those two.

The two cars were Mercedes W124 and W126. Now I have a different W124 which I'm considering in this topic.

Climate here is harsh so testing a car's AC would be thorough to give a good analysis. Nissans here are known for their good AC's (yet in cooling department, tho, not in quality and longevity of parts, but that's besides the discussion point). My friend's X-Trail nicely cools the cabin like instantly in +110F ambient. Other modern cars do that too here but not as fast. My father's Expedition 2010, for example.

 

[Joe C]

My 06 trailblazer originally had R-12 in it. Several years ago I switched it over to 134A because 12 was getting expensive and I'm not even sure if you can buy it anymore. The Trailblazer does have a leak so every couple of years I have to cough up $20. and dump some more in. They make a kit with a built in gauge with hose and connector with a can of 134 all set to use. A couple weeks ago when I used a trailer to get a lawnmower I noticed it was not cooling as well as it should so it looks like it is time to give it another shot. This for me is cheaper than taking it in to get parts replaced. Being 16 yrs old and starting to show signs of rust I know that this girls days are numbered now. I do not get extreme high temps here in Mich so A/C's from one brand of car to another are not considered an issue. If you say that this manufacture is better than the other I do not doubt you. I suppose going with higher cooling rated parts would help cool your car better but I'm not sure if those things are available....Something to google.
All manufacture's have propriety parts to fit their specific models so it will take some research to see what parts cross over to others.
Also consider the car's interior color will have some effect on how well it cools because a car with black leather seats will get a lot hotter than a car with light colored cloth seats. I'm sure windows area, and shading/tint color will effect the cooling capacity too. Also, many newer car models have interior air filters and if it is plugged up that will also affect the operation
My trailblazer has a light grey interior with tinted glass and it did not get nearly as hot as our Chrysler 200 did that had a black interior with black leather seats. My Honda get very warm on the inside and that has a darker grey interior and the windows are not as dark as the Trailblazers. That 200 was always hot inside even when in the winter

 

[PP Mguire]

Yea it's just going to be efficiency, insulation, and condenser size. The fan CFM, airflow, and the radiator/condenser being clogged also have a lot to do with it. With such tight spaces they'll get heat soaked quicker from the engine, and if the fan is weak or they're clogged at all you're immediately losing cooling efficiency. That's why my truck cools so much better because the fan blows huge amounts of air, has a massive radiator and condenser, and a lot of breathing room under the hood compared to my wife's Rogue.
Update on the flooding. Adjuster came yesterday and he doesn't think the damage is that bad. They want to remove a piece of drywall in the garage to help the drying process, and replace the carpet/padding. They will inspect baseboards from underneath but he doesn't expect serious damage. Meanwhile all of our allergies are going nuts because of this shit.

Edit: Those 124s look pretty cool blacked out.

 

[Smart_Guy]

Interior is light grey. Only dash is black but I covered it with not too dark grey upholstery. Even paint is min-range metallic grey. But all of the above mentioned are not direct issues in my case. Even under shade the AC does not work that great. Feels like the components are getting hit by the engine's heat or something.

In a good day to get a heat stroke here, temps reach ~122F. I personally drove in ambient temp of +115F. And guess what, the AC worked well because it happened on highways at speeds of +100 kmph. This could be a sign that airflow in the engine compartment is not that great in these cars, at least around the AC parts.

Oh yeah, engine fan is clutch driven. This means stationary it does not cool that well. Aux fan is a front pusher, and those are not as efficient as puller electric engine fans even for the condenser which has the radiator standing on they way to that puller electric engine fan if it's there. This is one thing I'm considering. I'm thinking of replacing the clutch driven engine fan. Honestly, the W140 (S-Class after 1992) has this same clutch fan and it's AC is superb, but I'm out of plans, really.

My W124 is the facelift model (was a pre-facelift, but I retrofitted the facelift on it, actually). It's even cooler (no pun intended) than the above attached pre-facelift W124 if modified the same.

@PP Mguire
I must have missed about the flood in this thread. Hope no one got hurt and not much material losses incurred.

 

[PP Mguire]

Interior is light grey. Only dash is black but I covered it with not too dark grey upholstery. Even paint is min-range metallic grey. But all of the above mentioned are not direct issues in my case. Even under shade the AC does not work that great. Feels like the components are getting hit by the engine's heat or something.

In a good day to get a heat stroke here, temps reach ~122F. I personally drove in ambient temp of +115F. And guess what, the AC worked well because it happened on highways at speeds of +100 kmph. This could be a sign that airflow in the engine compartment is not that great in these cars, at least around the AC parts.

Oh yeah, engine fan is clutch driven. This means stationary it does not cool that well. Aux fan is a front pusher, and those are not as efficient as puller electric engine fans even for the condenser which has the radiator standing on they way to that puller electric engine fan if it's there. This is one thing I'm considering. I'm thinking of replacing the clutch driven engine fan. Honestly, the W140 (S-Class after 1992) has this same clutch fan and it's AC is superb, but I'm out of plans, really.

Yea basically boils down to everything I said up there outside of maybe needing a recharge or freon leak. Other things outside of interior insulation is seals. Another thing to consider is most AC units are efficient up to about 30 degree below ambient so you're looking at high 80s inside the car at best when it's 115F.


@PP Mguire
I must have missed about the flood in this thread. Hope no one got hurt and not much material losses incurred.

Nothing damaged or anybody hurt. Was just the toilet hose that exploded causing a lot of water to pool up. Only real thing off of it is just the massive inconvenience and us probably getting sick.

 

[Joe C]

Yea basically boils down to everything I said up there outside of maybe needing a recharge or freon leak.

I was under the impression that Smart Guy stated that he just had his condenser and evap replaced. Those things should not not get dirty on the inside unless you have some major issues...but they are prone to developing leaks. If he is low on charge then SG needs to go back to whom ever replaced those parts to leak check the system. If they did plug up with some goo (I've seen this from severely contaminated systems) Then Every Thing will need to be replaced including the hoses. In the old days you could flush the system out with some R-11 but that stuff has been banned for a long time now. If they used something new to flush out cooling systems, I am not aware of it.
Smart guy, When they replaced those parts did they replace all the refrig. oil and filter driers too? It should be on the statement of your repair (at least here in the U.S. it should)