1996 Silverado air conditioner at idle

I have a 1996 Silverado. Replaced compressor, receiver/dryer, and condensor with autozone replacements. Flushed system. Replaced one of the lines. Seems to cool ok at interstate speed but at idle it does not. It has been in the 90's here but I feel it should cool better than this. I bought a HF scale and charged by weight. However, becasue it is hard to estimate how much is coming out of a can I think I have

2 extra ounces in it. Would that cause this problem? It cooled fine I think when I fixed the air but temps were not in the 90's. Could the fan clutch cause this and how do I tell if it is bad?

I have not put guages on it yet. What shoudl the pressures be?

I appreciate any help!

Reply to
stryped
Loading thread data ...

gotta ask - did you evacuate before charging?

Reply to
jim beam

Yes, I rented a vacuum and probably vacuumed for well over an hour.

Reply to
stryped

You should have installed an automatic adjusting orfice tube. They will help ac temps at idle by 5-10 degrees.

Reply to
m6onz5a

good - had to check.

walking through this, yes, i'd look at the fan and thereabouts. if it's cold at freeway, warm at idle, it's not dumping heat at idle. check all the shrouds are in place, the fan clutch works, and that you don't have dead leaves, bugs, furry animals in the condenser. obvious i know, but sometimes it's one of those things you short-cut if you're in a hurry.

not sure what fan type this is, but let's assume it's thermostatic - check the resistance to rotation with the engine off. if it's too loose or too tight, disassemble and inspect. if that's ok, [and this is not what you should really do, but let's assume you're stuck in the desert, and are very careful] jam the fan with something soft and expendable like a piece of cork. with the motor stopped of course. start the motor, and hopefully the cork will keep the fan from turning. when the motor is warm enough, the clutch should kick in, cut through the cork, and you're ok. if it doesn't, you need to test further or replace.

Reply to
jim beam

I never got satisfaction from pressure specs. Always 5-10 pounds off. I put in just under the called-for system refrigerant weight, and use a thermometer in the vent after the temp has stabilized. Then add a little at a time until the temp doesn't drop. Done. That's all at idle. You'll always have cooler air at speed. Refrigerant is working harder and air pulls away heat from the vehicle. A/C should kick idle up a bit. When your car has been sitting in the sun awhile it takes some time for the components to cool. Thermometer is the only way to know. Takes away doubt. You're not even sure it's cooling right on the interstate from what you said. Too much "seems" and "feels."

--Vic

Reply to
Vic Smith

Four Seasons part # 38903 for the auto adjusting orifice tube.

Chas

Reply to
m6onz5a

When I first repaired this thing vent tem was around 42-45.

Now going down the road it is 50-60 but will double check.

SHould I put more freon in it?

Reply to
stryped

don't overfill it. Putting too much freon in can make the compressor cut off & on

Reply to
m6onz5a

I never bought a new orface tube becasue the new condensor had one already in there but I wish I had now. Still, something does not seem right. It is blowing hot air out of the vents for the first 4-5 miles or so.

Reply to
stryped

On Fri, 10 Jun 2011 13:23:27 -0700 (PDT), stryped wrote:

Measure the temp. Your 42-45 means nothing if it was measured when the outside air was less than now. You just might be imagining things. Are you sweating in there? I don't know your truck, but when I've had a fan clutch its main purpose was for engine cooling, so if you've got an engine temp gauge that should tell the story on the clutch. My newer cars kick on the electric fans when the A/C is turned on. Did you put dyed refrigerant in? If you find the temp is really rising wait until it's worthless, then refill with dyed refrigerant and find the leak. Look at the compressor shaft first, then connections, then condenser. I had to take 2 rebuilt compressors back when the shafts started leaking after some weeks. One got me on my Florida vacation. I raised hell and kicked in maybe 50 bucks more for a new one. I'll never buy another rebuilt compressor. Then they put non A/C o-rings in the box with a new dryer, so that job cooled for only a couple weeks. Fixed that, and after a couple months temp went up again. Found a small leak in the condenser and replaced that. Been good since then. Went though a lot of refrigerant, and that stuff is expensive. So if you're leaking, check it all. I use this,

formatting link
Hard to find. First bought it Track Auto, but I never see it carried anymore. Bought a couple cans on E-Bay a few years ago and have plenty left. You don't need a dye injector, and don't pay a goofy price for pre-dyed 134. Put in a 12 ouncer of 134, shoot this in for a couple seconds, then load the rest of your 134. A good black light is better than the little penlights. My kid had a 4 footer from his teen-age days and we use that. But don't do anything until you're sure it's failing.

--Vic

Reply to
Vic Smith

That is 100% normal. Your truck is setting out in the heat and all of the interior, ductwork, and the rest are all HOT. It takes a bit of cooling for all of that to get that thermal mass cool enough that it isn't heating the passing air.

Charging by weight is a baseline. Then you connect up the gauges and a temp probe and see what you really have.

What did you flush the system with? When you applied the vacuum did you make SURE there were no leaks? I assume you didn't flush the system with the drier in line correct? If you did have the drier in line then you will need a new one.

First step. Get a temp chart.

formatting link
formatting link
Follow the testing procedure and see what you actually have for vent temps. See what the chart says you should have for your ambient temp. in both temp and pressures.

Then check over the system if things don't look right. Also check over the various doors in the system. Making sure the A/C works is a real PIA if a blend door is open when it's supposed to be closed....

Reply to
Steve W.

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.