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2005 GMC Envoy 4X4 4.2L Expansion Tube?
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MarineGrunt
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Aug 24, 2013, 11:35 AM
Post #1 of 37
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2005 GMC Envoy 4X4 4.2L Expansion Tube?
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The wife called me on the way home from work the other day complaining that the a/c wasn't working. I figured it was from the small leak in the rear evaporator and was low on refrigerant. I took it for a drive and noticed the driver's vents weren't blowing cold like the passenger side but eventually started blowing cool but still not cold. I'm able to see the actuator and can see it turning when adjusting the temperature on the driver's side. I already have the part because I thought it needed changed last year but when I vacuumed and filled the system all was cold. I'm just wondering if when the refrigerant is low it effects the system differently meaning that the driver's side won't get as cold due to location of a/c parts?
Either way since I have the $70 part I'm going to replace it. I was just kind of wondering.
The rear evaporator sure seems to be leaking at the fitting so I'm going to try new gaskets first. With my luck I'm sure I'll end up needing an evaporator though but at over $250 I'm gonna chance it first. I planned on replacing the orfice tubes too but the front one is not in the location alldata says. It says it should be where the lines enter the front evaporator. I'm positive they are not there. Is it possible our Envoy doesn't have one? I know on the Venture it just had expansion valves.
One more question. When we bought the Envoy last year the a/c wasn't working. I replaced the receiver drier last June. Should I replace it again or should it be fine? I haven't had any a/c problems at all besides that very slow leak. It was so slow I haven't had to add any refrigerant since last year. I can't remember if they say you should replace it no matter what kind of a/c work you do or only if you had some sort of failure.
Thanks
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Hammer Time
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Aug 24, 2013, 12:16 PM
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Re: 2005 GMC Envoy 4X4 4.2L Expansion Tube?
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The tube has to be in the evaporator. It can't be anywhere else because it has to be located after the "TEE" in the pipe so it effects the front only. This one is unusual in the fact that it uses a tube in the rear also. Most use a valve but not this one.
It is very common for a GM system to be colder on one side that the other when it's low on refrigerant.
The dryer should be OK as long as you don't leave the system open too long.
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MarineGrunt
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Aug 24, 2013, 12:38 PM
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I'll take a closer look and verify I'm on the right line for the tube.
I just took apart the rear fitting by the evaporator. One of the nuts didn't seem all that tight. It also pulled the nut and stud out. Do I need to use some form of sealant or Loctite on the stud? I realize it's the gasket or seal that provides the seal but didn't know if something had to be used on the studs. It looked like it had something on it before.
Reason why I think it's the fitting leaking is because after pulling the trim there is no dye anywhere except down by the fitting. That's on top and on bottom. Every line on the inside is completely clean. Most of the dye is concentrated on the inside on the stud that was kind of loose. I guess we will see.
Also, how long do you usually vacuum down the system? I have a 3 CFM 2 stage pump if it makes a difference on time.
Thanks HT.
(This post was edited by MarineGrunt on Aug 24, 2013, 1:44 PM)
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Hammer Time
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Aug 24, 2013, 1:45 PM
Post #4 of 37
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If it's only the seal at the fitting, then you lucked out. The studs come out all the time. You can use some loctite if you want.
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Tom Greenleaf
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Aug 24, 2013, 2:28 PM
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How long to vacuum: I hear this all the time running the pumps for hours on end. Hey! ZERO is ZERO so once you get to full vacuum and a couple more minutes stop and let it hold watching for it to rise.
Remember a full vacuum is only sealing OUT 14.7 +/- PSI of atmosphere not holding the operation pressures of refrigerant but a good clue you are good to go. Shops may proceed depending with a system that hold for 1/2 hour. I like longer (DS stay out of this) than that.
Yes when just getting slightly low many will be noticeably warmer on driver's side just because of the travel thru ductwork from evap. Could never speak for every vehicle by model year but never know of threads making the seal like residential plumbing, it's counting on a seal. What you don't want and happens is dissimilar or plain alloy metals really weld up sometimes impossible to separate without something breaking,
Tom
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Tom Greenleaf
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Aug 24, 2013, 6:29 PM
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Wrong - Water will boil at far below ZERO Fahrenheit at a full vacuum, like -90F or so. Water is also the only sublimate that will change directly from a sublimate to vapor without passing thru the liquid waste of time. When computer is up to par I'll show you with the jar I took off of Funk and Wagnell's front porch that Johnny Carson left behind after doing his Carnac thing on the Tonight show - oh just laugh.
What I mean is running the pump of any kind or speed longer than when it shows ZERO for the altitude is all you'll get. Running longer is just wasting the pump and electricity.
MG, the speed of any particular pump is just a time saver not better if less CFM than another just slower to get there.
Those who think you can take more from ZERO must work in D.C. they seem to do it all the time probably because there's some other form of cranial vacuum!
What I've never found a credible answer to is can moisture come OUT of hygroscopic oils or desiccant and so far I think but no good answer so is NO. I do think that would take both heat and vacuum to achieve and nobody I know does that. Guess is it does take some??
Tom
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MarineGrunt
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Aug 24, 2013, 8:05 PM
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I've always heard that pulling a vacuum is to check for leaks and to also get rid of any moisture. I've heard that from both auto and home a/c guys.
I've heard that if in a hurry a half hour is enough but preferably 1-2 hours depending on the CFM of the pump. I always let it run at least an hour but normally about 2 hours. I'm sure 2 hours is overkill but I'm in no hurry and figure it can't hurt.
Since I've heard so many different times I was just curious as to what the norm is for you guys.
So far the pump has been off for an hour and the gauge is still holding. When I went to pull the rear fitting it just didn't look like it was sitting on there right. It kind of looked a tad angle. I think the previous orfice tube might have been the wrong one or maybe just not made to specs or something. I didn't even realize it had a rear orfice tube last summer when I serviced the front. Well, the original orfice tube stuck out of the line a bit which wouldn't allow the seal to be completely compressed. The orfice tube does have a lip that goes over the line so it's suppose to stick out but something just didn't look right. I'm not positive about all of this but I know for a fact that fitting didn't look right and was angled a tad.
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Hammer Time
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Aug 24, 2013, 8:12 PM
Post #10 of 37
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You understand the vacuum thing OK. The time really depends on how much moisture is in the system like I said. With a new dryer, you don't need as much, assuming it wasn't left open for a long time. Overkill will never hurt. At least you know it's good and dry.
You should be using a white tube on this one, assuming it's inserted into the evap. If it inserts into the opposing pipe, then it takes a black one because it has support legs on the opposite end.
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MarineGrunt
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Aug 24, 2013, 9:00 PM
Post #11 of 37
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The front one is white and ended up being between two lines underneath the overflow tank. I just skimmed through alldata and assumed that they mentioned removing it to make things easier to get to. After pulling it I remembered having to do that last year when I replaced the front one.
I'm going to leave it under vacuum overnight just to be sure. I'm pretty sure it's good to go though. At least I feel good about it which is rarely the case! 
Thanks for the help. I'll let you know how it all turns out.
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Tom Greenleaf
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Aug 25, 2013, 2:53 AM
Post #12 of 37
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MG's quote ">>
I'm going to leave it under vacuum overnight just to be sure.
YES - let it hold. If it rises any it either wasn't done or leaking in somewhere, too frequently the seals of fittings, hoses or anywhere. The quick connect fittings can stink and not all connectors behave on all. I'm liking the right angle ones more, sometimes mandatory for tight spots.
The LACK of moisture is critical as about all PAG oils will change if exposed to air with its moisture and can in time be acidic that will destroy anything that can't take that in the system. Good argument not to use, used A/C parts near always wide open exposed.
If you really want to go nuts (I relate to nuts) when going for charge into the well held vacuum have a second pre-vacuumed hose locked to refrigerant source attached to high side when ports available or you can play tricks with gauges. It depends on how much stuff you have to work with but adding refrigerant to already attached source till your gauge you watched holding the vacuum show just positive pressure and you are as close to no air as you can get.
Good work stations are doing this for you. Many/most even high volume shops don't always go for the high buck Snappy stuff.
Try to keep thinking where vacuum and pressure is and what it is. The hose you attach is frequently just air inside the hose!
Notes: Just attaching and disconnecting hoses, spits small amounts in or out depending on what you are doing. Example is a low volume plain tire and you keep using a pencil gauge to get pressure exactly where you want it and each touch you lose some pressure/vacuum if the case,
T
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Hammer Time
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Aug 25, 2013, 5:05 AM
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It won't hurt anything to leave the vacuum on rest overnight but I wouldn't put too much credence into it if it leaks out overnight. I don't think there is a set of gauges that can be trusted to not leak over that period of time.
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MarineGrunt
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Aug 25, 2013, 6:03 AM
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Well, I checked the gauges this morning and the needle didn't move at all. I mean not even the slightest. I wanna say last year when I let it sit overnight it moved just a tad and I now believe that had to do with the rear fitting. At least I hope so. It was such a slow leak the system held a charge for a year though. I guess we'll know for sure come next summer.
I have 2.65 lbs for the amount of refrigerant. Gonna charge it and see what happens. It's suppose to be 96 tomorrow so hopefully it stays cold. If not I'll have to listen to Michelle moan about it! I'm sure it'll work just fine.
Should I add a couple ounces of oil to the system? I added an ounce to the drier since a little came out of it when I removed it getting to the orfice tube. Should I pour another couple of ounces into the fill hose? I guess I probably should've added what I needed straight into the lines before hooking any fittings back up. The refrigerant I have is straight refrigerant and doesn't have any other additives such as oil. I know these are kind of basic questions but I always feel better asking you guys so I get a definite answer.
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Hammer Time
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Aug 25, 2013, 6:11 AM
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Yes, I would add a couple more ounces. You can suck it in with the vacuum. With the system already under vacuum, connect the low side fitting but don't open the valve. Disconnect the other end of the hose from the gauges and submerge it into the oil. Now open the valve and observe how much oil it draws in. Shut off the valve when the right amount draws in. Connect the hose back to the gauge while it's still full of oil, leaving the coupler shut off. Once you connect the refrigerant supply, you can push the rest of the oil through the hose without drawing any air in.
There is also a way to get oil into it after it is charged if you have an oiler inline on you gauges.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Aug 25, 2013, 6:12 AM)
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Tom Greenleaf
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Aug 25, 2013, 7:40 AM
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Yes - agree to add 2oz oil over what you got out especially driers. You can drill a hole in wasted ones, heat and get more out for the count. Keep track of course,
Tom
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MarineGrunt
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Aug 25, 2013, 8:57 AM
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That's some great info there! I just planned on pouring it into the yellow hose before hooking it up. I was thinking that doing it that way I would end up losing some of it when getting the air out of the gauge hoses before hooking up to the system. Your way is a lot simpler!
Have to finish installing a new garbage disposal under the sink and then I'm going to get back to the Envoy.
Thanks again
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Hammer Time
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Aug 25, 2013, 9:15 AM
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I was never a big fan of the "measure the old oil" standard for determining how much oil to put back in. I know that's what the instructions say to do but all those instruction are working on the assumption that the system had the correct amount of oil to start with. If i opened up a dryer and found 5 ounces of oil in the bottom, the first thing I am going to think is that somebody overloaded the system with too much oil and putting that much back in would be the wrong thing to do. That method also doesn't account for oil lost through leakage so in all, I think it's a very inaccurate method of determining oil quantity.
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Tom Greenleaf
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Aug 25, 2013, 9:38 AM
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Yes - it's guessing at best. If no history you are lost. How do you guess a sudden blowout while operating? Smile - if seen right away by how much of a mess it made sometimes then decide the approach,
T
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MarineGrunt
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Aug 25, 2013, 3:53 PM
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Got it charged earlier. I took the temp in the vents and getting about 45 degrees. The outside temp was about 90 so kind of warm today. Is 45 degrees about right considering the temperature?
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Hammer Time
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Aug 25, 2013, 3:56 PM
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If you were on high blower and not driving down the road, that is awesome. It's about normal if you were cruising.
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Tom Greenleaf
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Aug 25, 2013, 3:57 PM
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Yes. I'd leave it be now if no other complaints,
Tom
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MarineGrunt
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Aug 26, 2013, 12:47 AM
Post #23 of 37
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I was driving down the road. It was at about 58 degrees while idling.
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Tom Greenleaf
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Aug 26, 2013, 2:44 AM
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Could be in the range of normal. Rear can rob from the front. Many things at a disadvantage at idle. Incoming air likely warmer and less density sitting still. Humidity can also be a substantial factor,
T
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Hammer Time
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Aug 26, 2013, 2:52 AM
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That's about all you can expect from that. You are basically running two systems off one compressor so they are never as cold as a single system.
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