Hi fellow Astrosafarians, I am having a bit of trouble with the A/C in my Astro and am a total n00b at this but am pretty mechanically inclined so I am confident that with some helpful instruction, I can be back in business before the summer months hit.
I have a 2005 Astro RWD with Rear AC and Heat. It was given to me from my parents. Has about 161k on the dial. I noticed after they gave it to me that the compressor wasn't kicking on at all when in defrost mode. I asked them if the A/C had been working lately and they said it worked in November when they last turned it on, but they had to get it up on the highway for it to kick in.
Lastnight I ran some tests. I shorted the low side switch connector and the Compressor kicked on. I then did the "no-no" test and pused the valve in on the high side but nothing came out at all which tells me the system lost all its charge. I have a feeling a slow leak developed somewhere, and the brutal winter we had did it in.
So what I want to do is see if I can locate the leak before trying to recharge it. I have read on here that some of you hook up an air compressor to presurize the system and listen for a hiss. I have a compressor and would like to do this, but I need to know the following:
What kinds of fittings would I need to connect my air compressor to the ac system to presurize it?
Can these fittings be found at any autoparts store?
What PSI should I use? (i think my compressor will do up to 120)
Would I connect it to the high side or low side or does it matter?
This is where I plan to start this weekend and will report back with the results as I am sure to have many more questions once the leak is located and hopfully corrected. Thanks!
I used a charging port cut the line and jammed a air chuck in the end with a hose clamp. I had about 120 lbs in mine when I heard the compressor hissing.
Unless you plan to buy/rent a vacuum pump and manifold gauge set and vac the system down before refilling I strongly suggest you do not use an air compressor. You will introduce all sorts of water vapor and crap into your system. If you're not planning to do the entire job by the book I suggest refilling it often or taking it to be repaired. It sounds like you're capable of doing it correctly from the troubleshooting you have done thus far.
You can by R134A with dye in it to identify the leaks with a UV blacklight. Thats probably the best route to take. Or shotgun every seal in the system....not so easy with rear air.
Thanks for the replies. The plan is to find and identify the leak as quickly and cheaply as possible. Then after repairs are made, call around and find a place that will vaccume and recharge it at a decent price. Or I may rent a kit from an autoparts store and do it myself. I have no idea how long the system ahs been open and am quite sure moisture is already in it so I am not too concerned with adding more in since I do plan to vac it afterwords.
I thought about the r134 with dye, but others have mentioned that if the leak is from the compressor seal, you will never see the dye.
@chevymaher: Did you vac out your system after replacing the compressor? Could you reccomend a particular compressor? I have looked online and found that many compressors come with oil in them. Wouldn't doing a vac after installing a new comp with oil remove the oil from the comp? Thanks again guys!
If the seals and valves have remained intact then the system is not open. The amount of moisture that could enter the system since November would be negligible...assuming you don't have a giant hole someplace.
The vac only removes air/moisture not oil. A flush would remove the oil but not the air.
@chevymaher: Did you vac out your system after replacing the compressor? Could you reccomend a particular compressor? I have looked online and found that many compressors come with oil in them. Wouldn't doing a vac after installing a new comp with oil remove the oil from the comp? Thanks again guys!
I have a vacuum pump and I to lazy to make a adapter for cars. No I never have. 4 compressors later. First 3 were junkyard models. One after another untill I fond a workable one. Last one is a new one. I have no problems coldest air in town. 7 years now since the first time it was open.
It is a good idea to vacuum it. I am HVAC certified. I am not saying it is good to not do it. I am saying I never do on mine.
No vacuming the system will not remove the oil. It works to slow.
I used a advanced auto, compressor. Didn't replace the required parts or vac it voiding the warentee. Which is a year. It is a couple years past the warantee if it was good now. So it lasted 3X the warantee period already.
And I really need to make the stupid adapter.
So thought I would post a follow up. I still haven't had time to pull vaccum and what not on the system given everything else thats been going on lately, but with it expected to be hot this week, I decided to try and just charge it with some 134a that has the stop leak in it and hope that would hold it. Well no dice.
The charge lasted less than a day. So clearly there is a pretty large leak in the system. I decided to use CMs method and quickly rigged up my air compressor and shot air into the system. I heard it hissing loudly underneath. I crawled under the van and found the line that runs to the rear ac has a nice hole in it near where it mount the the trans. What a dumb design. So looks like I am going to be ordering a new hose assembly. Anyone else here find a way to run it so its not vibrating up against the trans and getting holes? Oh and could someone find a diagram of where the hose connects up in the engine compartment? I imagine having to remove the engine cover inside... oh what fun. Its a 2005 Astro. Thanks again guys.
Your best bet it so sleeve the A/C line so it's not getting direct contact with anything. The line you are replacing to the compressor comes up from the fitting under the van, up to the compressor, loops over to the dryer and up front to the condenser. The hardest part is getting it out from under the van and put back in, but it's doable ( I've done it twice ).
Make sure you get a little PAG oil so you can lube the connections ( o-rings ) if the new hose doesn't come with any.
Drawing vacuum on the system will tell you if it's going to hold a charge, because it'll hold vacuum. I should have figured that out on my own, but I didn't and had the same problem, the charge lasted 24hrs. I had put the wrong gasket on one side of the manifold fitting and it leaked like a sieve.
I am far from an ac tech but in your original post you said it does not come on when in defrost mode? defrost is heater and does not nor should not turn on the AC compressor. But i'm glad you found your leak either way.
@ Redfury- Thanks for the info, sounds like its going to be a real fun weekend project... I ope after its done though I won't have any more problems with the system for a while.
@ Corsemoto- I was thinking something like that would help and will pick up some rubber tubing when I go to install the new line.
@ Markmitch- I think its a GM thing, not sure when they started having the compressor cycle in defrost mode but I first noticed it in a 95 olds achieva I owned years ago. I thought there was something wrong since it would come on but was told it was normal. The 2002 malibu I have does it as does the 03 S10 my dad had. I believe the reason for it is to reduce moisture to help keep the windshield from fogging up.
Yup, A/C is designed to come on with Defrost to help get rid of the moisture on your windshield, which is another reason to turn your defroster on when you are driving in thick fog or your windows are fogging up. A/C removes moisture, just like your ice chest removes moisture from your food ( hence the ice crystals that form on the outside of it if it's been in there for too long and your food tastes dry...too long and you get freezer burn ).
Update 05/31/14: Got the new line from rock auto installed. What happened was the bracket on the old line the secured it to the tranny housing had broken and allowed it to rub against the tranny which over time caused it to get a nice hole in it. Installed the new line today and cut up pieces of the old one to place over the aluminum parts of the new one for extra protection against rubbing. I never want to have to replace that line again.
Bought 4 12oz cans of R134a and recharged it. Front A/C is now blowing nice and cold, but the rear is not. Whats weird is, when I charged it the first time before discovering the leak, the rear was working. What I think happened is once of the cans I used on the first charge had stop leak in it. I have a feeling that stop leak has cause the expansion valve in the rear unit to get stuck closed. Really sucks cause from what I understand, trying to replace the valve entails releasing all the R134a I just put in it.
Can anyone here who has worked on the rear unit chime in and let me know what all has to be removed to access it? I was going to try tapping on the valve with a hammer to see if it would open up. Thanks!
I am going to address the use of stop leak on an AC system. The cans of stop leak they sell are a seriously bad idea. Anyone thinking of using stop leak should consider the problems it creates. It gums up orifice tubes and expansion valves so much so that it can make the high side pressure go crazy, which puts a ton of stress on your compressor seals. Not to mention lowering the efficiency of both the evaporator and condenser by plugging cooling rows. Plus in some cases it can build up under the service ports and throws strange readings to manifold gauges and SOMETIMES it can make it nearly impossible to recover the charge they legal way because of the junk it it creates under the service ports.
And when the time comes that you have to fix it the correct way you will be much happier that you didnt use that crap. And you will have less stuff that you need to replace in the long run.
^ yeah I wish I would have just used reg 134a the first go round. Luckily though, the hole in the line was so large that a good amount of the stop leak leaked out so hopfully, the only thing gummed up is that rear expansion valve. Front is really cold, ice cold when moving but that is a common complaint of others on this forum. Infact my parents told me they noticed having to get the van up on the hwy to get it cold before giving it to my wife and I.
Anyway, if someone can describe what needs to be taken apart to access the rear evap and expansion valve, id appreciate it.
I can't say exactly how to access a 2005 rear A/C but I'm sure it's similar to my 89. No magic. Just remove plastic on the driver side and it reveals itself. The coil and gizmos are low, near the fender, tire etc. The pillar acts as a duct to take the cooled air up to the output registers that span the rear ceiling.
I just retrofitted my R-12 system with 134a and for those considering it, it's a money saver over recharging with R-12. I replaced compressor, accumulator, orifice tube, condensor coil, plus refrigerant and oil, plus bought a vacuum pump and gauges - all for less than it would have cost to have a shop recharge with R-12.
Update 06/05/14: Well I don't know what happened but all of a sudden the rear a/c started working. Did a pressure check on it and its perfect. Lets hope it stays this way for a long time to come! Now on to various other things that need done to it like tune up, replacing the lock actuators and speakers in both driver and passenger doors and figuring out why the steering linkage is creaking. :mrgreen:
Update 06/16/14: Well the A/C system itself is still working well. Would probably work even better if I did the electric fan swap. But anyway now there is a new potential problem. Over the weekend I noticed that when then compressor kicks on, its making a metalic ratteling sound. So I guess thats a sign the compressor is getting ready to go. I read online that sometimes you can add some PAG oil and that will help. I also read that sometimes if the fan is not blowing hard enough across the condenser, it can cause too much pressure in the system which can also cause this problem.
So first question, is it possible to add PAG oil with out disconnecting the system and releaseing the charge? Most bottles of PAG oil i see dont come with a way to connect them like the r134 cans do.
I am really trying to not have to mess with the AC system too much more if possible. But at the same time I would hate to have the comp throw metal into the system as flushing the system given I have the rear unit looks like it would be a real PITA...
Yes, you can add PAG with the system closed. There's PAG in a can with just an oz or two of 134a, enough to get the oil into the mix. Wally's RV/auto section for just a couple dollars.
Lump
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