Chevy Astro and GMC Safari Forum banner

A/C Help... Im clueless & not very good diagnosing elec prob

2K views 18 replies 4 participants last post by  Lumpy 
#1 ·
Alright so heres what I have going on ... Out of nowhere last year my A/c stopped blowing out the vents. Found the vauum leak and fixed it.. About a month later my a/c went warm.. The system has Freon in it and is holding pressure and the a/c compressor kicks on and off.. Im mechanically inclined but not very knowledgeable of the a/c system.. Could anyone give me an idea where to go next with diagnosing this.. Thanks in advance !! Oh and its a 2002 with rear a/c RWD...
 
#2 ·
Sounds like it is low on refrigerant. When you hook a gauge to the low side. Does it just drop like a rock till the compressor kicks off. Then pressure comes up and it kicks back on. compressor should stay running constant at first with a steady pressure of around 35 lbs.
 
#5 ·
ok so update.. so i get home and i throw the gauge on that came wit the can of r134a i put in last summer and its reading no pressure and i pressed in the valve on the low side and nothing came out.. So the systems empty... So now the fun part .. Trying to find the leak.. SO just for explanation purposes all the checks i performed were last year when the ac started blowing hot.. at that point there was freon in the system and it was holding like 40 lbs according to the gauge.. but it was the end of summer so i didnt really worry to much about it.. fast forward to now and im sweating my jimmies off i wanna fix it lol.. so i popped the guage on today and here is where im at ... theres nothing in the system so i should assume the obvious that theres a leak... Now can i just add a can of dye and call it a day then look for the leak or do i need to charge the whole system? and are there any notorious problem areas where they tend to leak at i should look into? thanks
 
#7 ·
I agree that the dye is difficult to use due to the hidden spots that Maher suggests.

You have a vacuum pump? Or access to one? You're gonna have to suck it out anyway so suck it and see if it holds for an hour, 24 hrs. If it goes down in 5 minutes you've got a serious leak. If it loses 2 lbs in 24 hrs you could probably nurse it through the hot weather by just adding more freon every week. Then when the weather cools off, get more thorough with your search for leaks.

Can you plow positive pressure air into the LOW side valve? That might immediately tell you if the compressor hisses and is therefore the leak.

Lump
 
#8 ·
I dont really have many tools.. I got out of turning wrenches about 8 years ago.. I got like wrenches n stuff but no specialty stuff.. How do i pump pressure in the system? Like take the schraeder valve out n hook an air line up n blow into it that way.. Cause i can use my work compressor and an air line n do that..
 
#9 ·
Leave the schraeder in and pump it. If it's the compressor front seals, it'll hiss like a rattle snake with very little pressure. A bicycle pump might be enough. The valve doesn't fit regular tire valve fittings, of course. Just hold the air supply [I'm all out of love...] on the valve. If you don't have a compressor you could use the quarter machine at the Stop-N-Rob on the corner.

Side note:
There's actually a gas station/convenience store near me that has FREE air. That's a concept that I thought died decades ago.

Lump
 
#12 ·
Pump it with engine off. You're not circulating anything through the system, just putting pressure on the seals. Of course, if there's a hole somewhere else, that might also scream out [Here I Am...]. In that case tell that darn system how much trouble it would be [Without You...]

You could also pump the high side. You can't hurt anything that's working. It's meant to routinely take up to like 300 psi. The low side is closer to the compressor is the only reason why I might start there.

Mine had a failure at the compressor seals AND at the condensor coil.

Lump
 
#13 ·
I had this same problem with my 2005 Astro also with Rear a/c. I hooked up my air compressor to the low side and pumped about 80psi into the system and heard a loud hiss comming from underneath the van. Turned out the mounting bracket that holds the A/C line running to the rear had broke allowing the line to rest on the bell housing of the tranny. Overtime the vibrations caused the line to rupture. Ordered a new line assembly from Rockauto.com and installed it on a saturday afternoon. A/C has been working great ever since!
 
#14 ·
ok so i got home and took off the lowside cap and found all kinds of fresh dye.. so my assumption is bad valve... replace the valve and went and picked up one 12oz can cause untill tomorrow thats all the money i had lol.. so i put it in obviously its not gonna get cold but i could feel a change in temp and the compressor was cycling on and off and i didnt hear no hissing while it was running so i think im good lol... Then i shut it off n it starts hissing from the pass side far corner by the fender/firewall.. hissed like 10 secs n stopped... started it back up left it run and a/c cycled on and off like normal still.. turn it off again and same thing hissed for like 10 secs then stopped.. so is there some kinda pressure release back in the pass/ corner firewall area that releases pressure when the vehicle goes off or is that another leak i need to locate over there.. its dark but looks like theres an ac line over there.. thanks again guys
 
#16 ·
alright so I came out to my van this morning and started it up.. popped the hood turned max a/c on and now my a/c compressor is no longer cycling on and off .. So im pretty sure the can I put in last night leaked out.. So back to the drawing board... Gonna wait til lunch time then I ll put some pressure on the system n see where that gets me.. :banghead:
 
#17 ·
If you end up evacuating the system, I suggest spend an extra five bucks and replace the two valve stems in the schraeders. You'll need a schraeder tool from LAP, the valve caps with the little slot won't move the AC style stems. And I recommend using stems made for AC, not for car and bicycle tires. They're under a lot more pressure in AC, have different rubber in the seals.

I think the schraeders will always allow a little freon/oil/dye to escape just in the process of installing and removing the gauges. Especially the high side, with 200-300 lbs of pressure trying to get out, removing the gauge connector just lets it "burp" a little bit. So I'd expect to see dye there, just not escaping continuously.

Lump
 
#18 ·
Lumpy I already swapped the low side Schrader valve , with the tire valve tool lol... Didn't have a problem and put the new one in fine.. And to give you a heads up im using one gauge on the low side.. it came with the one can of r134a I used to charge the system.. I don't have the whole proper evac and recharge system a shop would have.. Im at the mercy of what walmart has lol.. Im pretty sure my system is completely empty.. I gotta get back in there with an air line and pressureize the system so I can find that leak..
 
#19 ·
I use that low side only hose/valve thing too when I'm just adding freon or oil.

If your system has gone empty, and especially if you blow shop air into it, you should vacuum pump it. That causes any water in the system to boil to vapor and get drawn out. Water in a refrigerant system is no bueno. It freezes into ice and blocks passages.

Not sure if you can get a loaner vacuum pump from LAP. You'll need a regular 2 gauge, three hose manifold set to use the vacuum pump.

Vacuum will also tell you if you have a leak. Suck it down till the gauge pins and close the valves, shut the vacuum pump off. Check the gauges in 20 min, 60 min, 24 hrs whatever, to see how fast (if any) your leak is.

EricTheCarGuy has some good YouTubes on how it all works. Scotty Kilmer does too but his high pitched, screechy voice makes my ears bleed.

Lump
 
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