Chevy Astro and GMC Safari Forum banner

Getting A/C so cold it blows snow out of the vents.

4K views 20 replies 11 participants last post by  redfury 
#1 ·
Okay, so I watched this video of a guy that rented a new chevy Equinox and the A/C was blowing tiny bits of frost into the interior....and you hear of Ice cold A/C from people that brag up their systems.

What I want to know is, what exactly needs to be met in order to get a system THAT cold. After finally fixing my A/C to the point where it holds a charge and keeps it in, drops the vent air at least 20F from ambient...I'm thinking that I could have better air than I do. Now, I pulled a vacuum for an hour when I opened it up last time due to adding too much oil to the system and causing all sorts of wild pressure that blew green PAG oil all over my manifold from the top of the compressor. I replaced the seals and recharged. I ran it for a few days and rechecked my charge, both with gauges and with my non contact thermometer. My pressures on both the low and high side are pretty much spot on where they should be vs. ambient temp.

Now granted, it gets cold, but it doesn't get cold FAST. If I'm running front and rear air, about 10 miles into my drive is when the cabin finally starts to get a little chilly and I have to take it off MAX and slow down the fan speed.

I'm just curious, and want to know more. Is it the orifice tube that has that much control over how much coolant makes it to the evaporator?

The other possibility could be from having too much oil in the system originally and it needs to be circulated out of the evaporator for better contact between the liquid coolant and the evaporator lines? My Dryer is new and I found a foam rubber insulator for it at the JY and wrapped it with that to help with thermal loss.

Any ideas?
 
See less See more
#2 ·
I'm no help. My R12 converted to 134a blows, like yours, a couple decades below the ambient. When the interior temp in the van is 127F that's not exactly snow coming out of the vents.

Also like yours, it takes a few miles to start blowing cold. And since most of my trips are only 2 miles or so, it never really does anything.

So. Could I have been any more useless with that reply?.. :banghead:

Lump
 
#3 ·
20° lower than ambient is normal at slow idle. At fast idle, it should do better. What are your running pressures?

Our vans didn't come with an AC fan from the factory. My '89 240sx with clutch fan had a front-mounted e-fan that only kicked on under a certain RPM and only if the AC was running. That thing blew ice cold at idle and at highway speeds. Having said that, it's a MUCH smaller vehicle than an Astro.
 
#4 ·
When the A/C switch is set to Max/AC it is recirculating the inside air to maximize the efficiency, but we have a He// of a lot of air to recirculate. I have gotten a small blowing 29 degrees out of the vents on a 90 degree day but that was just a fluke. The expansion valve was stuck. To get that out of our vans you have to wall up the cab, modify the orfice tube and add a extra fans at the vents and on the condensor. Then Maybe.....
 
#5 ·
You can get your vehicle as cold as design limits permit, plus 3%.

You need a very good fan clutch, and shroud. Add electric fan/s for idling
and city traffic, they help. Do NOT remove engine driven fan.

Insulate body and interior thoroughly. "Dynamat' or equivalent will help on
the roof above the headliner.

Seal all gaps at the plastic evap box to keep cold air in and engine heat out.

You need a 100% leak free system, and also air flow must be correct and leak free.

Your condenser should be new, or very clean. On an older vehicle, this makes all the
difference in the world. It may look fine, but the corrosion is invisible on aluminum.
If you want it cold in your car, be thorough. Leave nothing to chance. Keep in mind the
newest Astro van is over ten years old. The whole system needs to be gone through.
Every little thing that gives you a degree or two improvement is what you are looking
for. You aren't going to find some big bolt you can replace that will make it 15 degrees
cooler. It doesn't work that way. You are trying to return the whole system to the operating
efficiency it had over a decade ago. Heat transfer and airflow are critical. You must
understand how the whole system works, or should work.
 
#6 ·
On a 90 day, I was getting 40/225 (lo/hi side) and the dryer was sweating bullets. I think I need to get in and seal up my under dash ventilation tunes better. Seems like I was getting more forceful airflow through the dash vent when the heat was on last winter. Also, I lose my vents when I accelerate, so something is up with my vacuum routing... Or I have a faulty one way valve.

Cleaning would certainly help. I wonder how much trouble it would be to get a foaming type cleanser into the evaporator core. For what it's worth, I am just happy I have successfully brought back to life this hacked out front/rear A/C.

Another thing to note, I'm running an S10 compressor. The difference between it and the Astro is a larger pulley.
 
#7 ·
I'd get the vacuum problem sorted first.

Next, I'd clean the condenser with Spray Nine and spray off with your garden hose. If you've never cleaned between the radiator and the condenser, you wouldn't believe how much crap accumulates in there.

Then there's this stuff for the evap core:
http://www.amazon.com/Lubegard-96030-Ko ... go-ipad-20
 
#8 ·
For max coldness out of the vents. It is in the amount of charge the system has in it. I am not talking what the factory specs say. If the charge is to low it is finished boiling before it reaches the middle of the evaporator. So effectively only half is producing cold air.

If it is overcharged it is still liquid half way through the evaporator before it starts boiling. So the side with liquid is not producing cold air like it should.

It should start boiling when it enters and be done at the opposite side. That way the entire surface of the evaporator is producing cold air.

In college I made trainers. Took a deep freeze apart. Put it on a board on the workbench. Bent the cooling lines up untill they fit in a little metal box I made. Literally hold your hand on the evaporator while you fill it to learn this principle.

It takes some tinkering to find it if you can't feel the evaporator. Feel the low pressure line coming out of the box. If it isn't ice cold it isn't boiling through the evaporator. It was done long before there.

Mine on a humid hot 90 plus degree day wont make ice but it will blow steam like opening the freezer.
Sitting in the sun after running. Go in the store and it is like being in Lumpy's front yard in there when you get back. Start it and let it idle with the air on. It is cool in there by the time I load the groceries in the back. It was 98 degrees the other day and I am riding around with it on bi-level blower on 2.

I messed with it a long time before I got it working like that. Used to get warm sitting in traffic. Sweating untill you picked up speed. I don't miss the way it is supposed to work at all. Electric fan instead of the mech one. Cleaned the condenser. I definitely use more refrigerant than it calls for. 3 1/2 cans is what mine likes. Just front air. Over a half can more then it supposed to have.
 
#9 ·
the vacuum loss during acceleration is most likely a cracked vacuum line. just fixed this same problem on my van last week.

as others have recommended seal up everything. I did this in the last few weeks because of the same problem you are having. everything you do will help a little bit. In my case the biggest culprit way funny enough my front heater core, the original owner had told me he replaced it when i bought my van. since owning it my heat in the winter and AC in the summer has been sub par. messing around trying to figure out the heat problem ended up fixing both my heat and AC. The PO did not put the replacement core exactly where i should have gone and didn't bother putting the two retaining straps to hold the core in place. that gap in placement caused massive amounts or air to mix all wrong, lets put it like this at the core my IR temp gauge gave me 160 degrees but at my vents i would get 95 degree. After that fix and some sealing around my vents started giving me 145-150 degree air. same went for my AC last summer best vent readings were 55-59 degree, today from that fix alone it dropped to 46-48 degree. then i resealed the brittle evap housing of all the damn holes it had and now at my vents while driving get about 42-45 degree air. I have a few more things to check as my idle air temps on a 90+ day are a bit high around 60 degree
 
#12 ·
Is the air temp at the vents the issue, or is it other things... or a combination of numerous things!

Regarding vacuum and the heater coil valve, I simply tie-wrap mine shut during summer season. In fact, right now my heater hoses are no longer even hooked up. The A/C (even single unit) does a pretty fair job and always remains cold. Strong fan and LARGE shroud are ESSENTIAL to cooling at low speeds or idling! Once you get over about 30mph... the air rushing in does the work!

I suspect that one BIG issue is not the fact that you may have adequate and very cold air coming out the vents.. but how fast you can push that air too. I've seen cars that push almost the same volume of air on low-med that our vans push on full blast! Our fans are not the greatest! The air vent temps will also change depending on the volume of air pushed also.

One of the bigger issues may be trying to cool the MUCH larger volume of the cabin of the van, compared to a car! The area of sq/ft is hugely different! I think this is a huge issue. Dual air DOES make a big difference in full length vans!

Finally though, the BIGGEST issue may simply be the huge ROOF area pumping in more heat than what can be removed. The sun is relentless on the surface. Insulation is obviously key!

So like five10freak said, it may be a bunch of things that add up to make it all work better!
 
#13 ·
Mmusicman brings up a good point. If you put your blower fan on low then check the output temp you'll find the temp is really low, but the van is still hot. Just not enough air volume moving across the evaporator. Do you want low temp at vent or low temp in the rest of the van? How come no one is bringing up the rear A/C adding to the efficiency of the whole system?
 
#19 ·
Well, I'm running my big old Thunderbird E fan on high when the A/C is commanded, so I know I'm getting more than enough flow across the condenser. I may have to tinker some with the coolant charge and check a few things out.

The Radiator/condenser pocket is clean, I replaced the radiator last year or so. The only thing I wonder about is if I've gotten cottonwood stuck up in the evaporator core. I'll have to do some more checking with my IR gun and see where I am with my evaporator efficiency. I would think it's good since the dryer gets down to about 50F if I remember right. I'll have to do some checking.

I had some initial doubts about the larger pulley'd compressor, but I'd think it'd just turn faster with the larger belt at idle. Good stuff for me to chew on and check out. I'll update with pictures and/or numbers from the IR gun when I get back on it. For now, I've got a boat to paint!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top