What makes the AC not cold enough?

[cujoe_da_man]

I know, it's winter, who wants to talk about car AC right?

But I was thinking about it the other day and how these cars don't have the best AC systems. I get that they were "cheap cars for cheap people", but (much like the engine vibration issue), I've had just-as-cheap cars that had way more effective AC systems in them.

What about these cars makes the AC suck so much? I get the basics, you have a condenser, accumulator, bottle of refrigerant, a compressor, seems like there shouldn't be much deviation from much more expensive cars. What would make the system work much better/more efficiently?

I'm just curious is all and want to learn more about this since most AC related vids or articles don't really delve into this. I'm assuming because there aren't barely any cars that have lackluster AC systems like this these days.

[fetchitfido]

IIRC the S-Series was a test bed for Zyxel, an A/C compressor manufacturer. They changed the compressors fairly often, almost every model year, just to test out a new compressor system. They never put a "We know this setup works great" system in the S-Series...always a "Lets try this and see what happens" system.

[cujoe_da_man]

So, just bad compressors then? I wonder what makes them be that way. I used to rebuild compressors at a shop here in Michigan and while there are dozens of different kinds, the basic operations were all the same: pump the refrigerant through the system.

Maybe too-small pistons?

[fdryer]

Saturn and Ford uses similar ac compressors. No pistons. Variable displacement compressors using five sliding vanes. Other manufacturers are using VDCs too. Complicating vane type compressors is a mechanism to vary displacement. One member shipped his blown vdc to me. I disassembled it, took snapshots of everything and made a photo album here for anyone to see a vane compressor apart. Unfortunately, when this site needed an upgrade to a new server, all photo albums ceased to exist. They remain in the old server but the site administrator is unable to transfer them to the new server. The mechanism controlling output displacement is a mystery to me without engineering drawings and description of how it varies displacement. Piston compressors are fixed displacement. In operation, the thermal expansion valve continually adjusts a needle metering refrigerant flow according to refrigerant temperatures in the evap coils to prevent freezing conditions that can freeze condensation on fins and coils, building up frost turning into ice until the evap coil becomes a solid block of ice with little to no air flow. Some r12 systems did this, most likely when a leak occurred that made the evaporator coil run very cold. An older type of expansion valve was used. The block type txv used everywhere controls evap temps to maintain above freezing temperatures until refrigerant levels decreased to around half capacity. The compressor varies output displacement to (I'm not 100% sure) increase output at low rpm then gradually lower output as rpm increases. I think this is to help overall efficiency.

My guess is the S-series with little to zero window tinting, uninsulated interior against outside heat and cold works against the ac system, increasing heat loads. Some here say it's fine and cold. Perhaps in cooler regions while hotter regions say their ac never was great. My L300 has all black interior, the best at absorbing infrared heat from the sun but when ac was working, it cooled off as vehicle speed increased. Forced airflow thru the condenser coils helps ac operation. The upper black dashboard remained hot all the time from summer sun.

My L300 uses a VDC and was very cold in summer high heat and humidity. The auto climate control allows setting temperatures from 60F-90F. Left at 60F, once a few miles of driving cooled down the interior, I had to set blower speed to minimum speed from getting cold wearing shorts and T-shirt. With a car full of people, it was very comfortable. As years passed I used a dial type temperature gauge and measured lowest output vent temps at around 42F. Service manual states lowest expected vent temps is 42F. Meat locker temps.

[cujoe_da_man]

Guess that was one compressor I never got to tear down, everything I ever worked on was all piston driven

I'm going to be looking at ceramic tinting this year, I've been watching a lot of vids about it and one of our local window shops does installations. The ceramic material is reduced down to a nano size to allow for light to pass through, but blocks a great deal of infrared light from getting through.

The downside of the ceramic tint is (ironically) you won't get that nice infrared heat from the sun during the winter, so you'll have to run your heater as if it were 6am and ten degrees out... but, I figure that's a small price to pay. In my experience with heating and cooling things, it's far easier to warm something up than it is to cool it down, it takes far less energy to create heat than to create cold when it does not happen naturally.

Even if the tint doesn't work 100% like they say it does, something is better than nothing and at least the car will look nice with it. I'll just get legal tints all around the windows and they have a clear "tint" you use for the windshield.

I'm also wanting to do some sound deadening throughout various parts of the car and Kilmat is one of the better rated materials that not only reduces cabin noise, it's also very efficient at reducing heat transfer as well. I've seen vids of them using it around the hood of the car to stop engine vibration through the hood itself which is where I hear the most noise coming from, especially at certain engine temp/RPM combinations. I tried tightening up the little rubber bumpers, but that only does so much.

I need to replace my blower fan too, I'm not certain, but I think it could be failing, it's giving me the signs and they aren't so expensive that I would regret changing it. I'm thinking that might be the reason for the overheating of the wiring at the relay, it's causing the leads to overheat and melt and now causing a large resistance issue which is just making things worse. I'm about to pull the wiring for the relay out and bypass the fuse block altogether. I can snip the ends off and get new ones, making sure I have good connections all around.

Ahh, the life of a car owner.

[trottida]

Originally Posted by cujoe_da_man

I've seen vids of them using it around the hood of the car to stop engine vibration through the hood itself which is where I hear the most noise coming from, especially at certain engine temp/RPM combinations. I tried tightening up the little rubber bumpers, but that only does so much.

You could grab a hood pad from a donor SL2 or SW2. The SL and SL1's did not come with one.

[cujoe_da_man]

I thought about that too, but the problem remains that there are no early 2000's Saturns within a hundred miles of where I live. Michigan seems to be the only state that doesn't have a surplus of used/junked Saturn's. We don't have much of anything, really, most of Craigslist is empty of things I search for.

But if I want a completely rusted out 2002 Silverado with bent frame for $6000, I'm all set!

[fdryer]

The bev community, specifically Teslas, have a new (possibly serious wrinkle in regards to safety) - new Teslas are equipped with heat pumps (reversed ac system) with our northern Canadian neighbors suffering catastrophic heater failures in extremely low temperatures. Reports are describing total failure of heaters with outside temps around -50F/-58F. New cars. Over the air updates are occurring to address these issues and the NHTSA and Canadian DOT are investigating Teslas failing to provide heat in extreme cold temps. One snapshot showed a Tesla ac compressor with its head removed revealing a scroll type compressor and the tell tale greenish yellow dye/oil coating everything. A battery driven electric ac compressor used as a heat pump in winter then switched valving to create cold air for summer.

Every conventional 'ice' vehicle uses gasoline or diesel to create power. Up to 60% is wasted energy in the form of heat from combustion, absorbed into the engine block, motor oil, cooling system and expelled in exhaust. All waste energy that doesn't spin tires. In effect, our cooling system is providing free heat as soon as the engine starts up. When at operating temperatures, free heat whenever needed all year 'round. As a skier familiar with dressing for freezing temps outdoors for several hours at a time, I welcome all the free heat from my car and use it more in cold weather since it's free.

Some members have to open their windows from too much heat in their S-series cars. As you put it, it's easier to warm up the interior than it is to cool it.

[cujoe_da_man]

I was just hearing about the Tesla's the other day and their heat problems!

I have noticed just how efficient the Saturn's are at engine cooling, though. Even in the sweltering heat, it takes forever for that needle to get up to the point where it needs to run the radiator fan (unless I'm running AC, of course). Previous cars of mine would turn the fan on nearly as soon as I stop somewhere or at least it seemed like it.

This is actually my first winter with the car and while it takes a bit to warm up, once it does it's like "open the damn window!".

So, I'm gonna be the test bed for the ceramic tint and see how that does. I know I won't get super cold and turning it into an icebox, but if it works as well as they boast, the AC won't have to fight the continuous infrared that's blasting through the windows.

When I had the headliner out, I did line the roof with some of that silver radiant barrier, it's equivalent of something like R5, it's really low, but it's meant to keep the infrared light out. I also have a mat of it under the dash too. I also use the same stuff in a cooler with some homemade ice packs, I can run a full stocked cooler for almost 5 days with no ice!

[dummo]

I've had a dead AC since I bought my SW2 ten years ago. I charged it once and it blew cold and then it was useless the next day. It's above my head to fix myself so for a decade now I've left it alone. - I can't remember a day driving last summer where I really wished I had it. (Connecticut)

I'll get it fixed or fix it some day.

[cujoe_da_man]

I'd never tell anyone they're wrong for not having AC. Some people are just fine without it. I have my days where the windows down and rolling through town is just fine, but there's those days where the sun is high overhead and the tires are melting into the ground that a cold blast makes for a good end to a work day

[cgg17]

Replace the condenser, filter/dryer, and lines. Fill up the system, check pressures. If the pressures are correct, you're done. If the pressures are not correct, replace the compressor. Other than that, S-Series A/C is pretty darn good.

[cujoe_da_man]

I actually did replace the compressor this summer because the clutch on the old one was fried (it was only about $25 more to replace the whole thing). The shop said everything was up to pressure and no leaks detected during the vacuum test and after filling it.

I wouldn't rule out maybe other parts not being up to par, I mean it is a 20+ year old car, but I've read plenty of other threads about the same issue of it not being as cool as more expensive cars even after replacing everything.

[alordofchaos]

Is the problem with your AC the air flow, or the temp of the air?

Originally Posted by cujoe_da_man

I need to replace my blower fan too,

When you do that, have the nose of the car pointed slightly downhill and try hosing off the evaporator

http://www.saturnfans.com/forums/sho...d.php?t=200618

also check blend door operation, might also be losing some air through leaks /blockage at foam seals along the way

[alordofchaos]

Originally Posted by dummo

I charged it once and it blew cold and then it was useless the next day. It's above my head to fix myself

So, everything works, you just have a leak

In both my Saturns with AC leaks, it was a leaky Schrader valve. UV light ($10 or so) can help find leaks elsewhere

It's a glorified tire valve, really. It unscrews, with needlenose pliers or a special tool like one used for bike/car tire valves, and you screw in a new one ($5 -$15 or so for a set with new caps)

There are videos on YT showing how to use an AC pressure gauge set (you know richpin has one, lol) and these are usually in the free loan a tool programs. Vacuum pump was around $90 at HF last I checked.

[cujoe_da_man]

Originally Posted by alordofchaos

Is the problem with your AC the air flow, or the temp of the air? When you do that, have the nose of the car pointed slightly downhill and try hosing off the evaporator

http://www.saturnfans.com/forums/sho...d.php?t=200618

also check blend door operation, might also be losing some air through leaks /blockage at foam seals along the way

I think I was hitting around 38 F at the center vent which is right on par with what others have said, that's why I was asking why the system doesn't get any colder.

I know that sitting at idle will cause the system to slow down, that's just a fact of life, but even at higher speeds when it's blazing hot out it just doesn't seem to keep up.

I will be checking the internals when it gets warmer too, I did replace that little screen on the firewall, so I certainly wouldn't rule out that maaaaybe something got in there and caused it to plug up, but I mean it would have to be A LOT of something.

Could there also be something with it pulling hot air in through that vent on the firewall? I mean it is sitting right under the hood in the hot sun and I personally have never seen another car with an inlet like that. Maybe make some kind of ducting to get it down away from the hood? If it even makes a difference.

[cgg17]

Originally Posted by cujoe_da_man

I actually did replace the compressor this summer because the clutch on the old one was fried (it was only about $25 more to replace the whole thing). The shop said everything was up to pressure and no leaks detected during the vacuum test and after filling it.

I wouldn't rule out maybe other parts not being up to par, I mean it is a 20+ year old car, but I've read plenty of other threads about the same issue of it not being as cool as more expensive cars even after replacing everything.

Whenever the system is opened the filter/drier should be replaced. That can cause ineffective cooling due to the increase of moisture in the system. It is around $30 itself.
Condensers also get sludgy near the bottom with 20 years of use, so they will generally have less cooling ability than a new one.

[cgg17]

Originally Posted by cujoe_da_man

I think I was hitting around 38 F at the center vent which is right on par with what others have said, that's why I was asking why the system doesn't get any colder.

I know that sitting at idle will cause the system to slow down, that's just a fact of life, but even at higher speeds when it's blazing hot out it just doesn't seem to keep up.

I will be checking the internals when it gets warmer too, I did replace that little screen on the firewall, so I certainly wouldn't rule out that maaaaybe something got in there and caused it to plug up, but I mean it would have to be A LOT of something.

Could there also be something with it pulling hot air in through that vent on the firewall? I mean it is sitting right under the hood in the hot sun and I personally have never seen another car with an inlet like that. Maybe make some kind of ducting to get it down away from the hood? If it even makes a difference.

Anything below 32*F will cause the evaporator to freeze over, it is designed to not reach that point. Once the evaporator freezes over, you will loose AC functionality.
It is designed to not reach that point. Other vehicles achieve this by cycling the compressor on and off once it falls below a certain temperature to prevent freezing the evaporator.
It sounds like your system is working properly, as you have very cold temperatures at the vent. As for flow, it could be that the foam seals around the vents and HVAC tubing are drying/rotting out, allowing more air to escape before coming out of the vents.
Other than that, you could purchase a light colored dash cover to keep some heat out of the dash and surrounding areas. I did for my 95 wagon and there was a noticeable difference in temperature between the naked black dash and the light colored dash cover.

[cujoe_da_man]

Maybe I'll look at redoing the whole system later on. I only just got it recharged at the end of August last year, so I'd like to at least get SOME of what I paid out of it :P

[cgg17]

Originally Posted by cujoe_da_man

Maybe I'll look at redoing the whole system later on. I only just got it recharged at the end of August last year, so I'd like to at least get SOME of what I paid out of it :P

If it is showing 38*F, it is fine. I would try a dash cover and maybe blow out/ check the HVAC ducts that are under the dash and center console. Unless the system has to be opened again, I would leave it alone since it is producing cold temperatures.