Mazdax605
Mazdax605 UltraDork
5/17/16 6:59 p.m.

Hey guys,

Recently the A/C on my 04 Suburban quit working. It's the only vehicle I have with working A/C(well it used to be). I thought it was an issue with the blend doors acting up as they have in the past. Today I did some investigating, and noticed the compressor clutch wasn't engaged. This could be why it isn't working(duh). My question is could it not be working due to a leak in the system, and not the proper pressure to make a switch allow the clutch to engage? Or could it be a faulty clutch? Anyway this doesn't cost a small fortune? I'm on strike at work, so no income really aside from my wife. I would love to get this working again. Any help is greatly appreciated.

Chris

imgon
imgon Reader
5/17/16 7:21 p.m.

I spoke to Andrew this afternoon and he said the most likely culprit is a leak. I'll give you his number tomorrow and he can see what's up.

Vigo
Vigo PowerDork
5/17/16 7:30 p.m.

Props for being on strike!

It most likely is NOT a bad clutch. If the clutch were trying to engage, you should be able to find the compressor clutch relay and feel it clicking off and on as you take it in and out of the socket. If you suspect the relay and don't have any tools to test if you can swap it with something else you know is working and see if that stops working.

It is more likely to be a pressure issue. What's your budget for diagnosing this? A cheap set of gauges is $50 or less (but they will be junky unless you're buying something used of good quality). If that is too much, can you borrow some? At worst, some cans of refrigerant come with a low-side pressure gauge built in (although usually these are a ripoff for the amount of refrigerant you get). If you are friends with any other local car enthusiast's i'd bet money SOMEONE has some kind of gauge setup you could borrow.

Mazdax605
Mazdax605 UltraDork
5/17/16 8:53 p.m.

I'm hoping it's not a major leak as I can't afford any major repairs. Thanks Chuck.

t25torx
t25torx Dork
5/17/16 10:12 p.m.

Yeah sounds like a leak has just reduced the pressure so the pressure switch isn't allowing the compressor to kick on. If it's a small leak I had good luck on the C55 using a can of that A/C Pro Stop Leak ($22) and then adding the required amount of R134. If you can wait, buy the R134 on Amazon, the Dupont kind, it's way cheaper than buying it at Advanced, like 3 cans for $15.

I use the gauge set from Harbor Freight, they work good once you thread tape all the connections. Find someone that will let you borrow or even come over and help you use them.

NickD
NickD Dork
5/18/16 5:29 a.m.

If I had to take a guess at the leak, I'm going to say it's the lines running to the rear evaporator core as they all seem to develop a leak back there.

Vigo
Vigo PowerDork
5/18/16 11:20 a.m.

When you eventually recharge it with the money you dont have to properly diagnose it, put oil with dye in it so you can find the leak later after you have to recharge it AGAIN. Just trying to espouse the virtues of putting the money/effort in diagnosing up front. On the plus side the only leaks that are 'major' are the evaporator and condenser because they cost money to replace. Everything else is either cheap, easy, or both. Unless the compressor leaks out the shaft seal.... hehe

Mazdax605
Mazdax605 UltraDork
5/18/16 10:02 p.m.
Vigo wrote: When you eventually recharge it with the money you dont have to properly diagnose it, put oil with dye in it so you can find the leak later after you have to recharge it AGAIN. Just trying to espouse the virtues of putting the money/effort in diagnosing up front. On the plus side the only leaks that are 'major' are the evaporator and condenser because they cost money to replace. Everything else is either cheap, easy, or both. Unless the compressor leaks out the shaft seal.... hehe

What is the proper way to diagnose the problem? If I can do it correctly and get it fixed properly I will go that route. Unless of course if it's thousands of dollars then I can't afford that.

Chris

t25torx
t25torx Dork
5/18/16 11:02 p.m.
Vigo wrote: Everything else is either cheap, easy, or both. Unless the compressor leaks out the shaft seal.... hehe

Don't even joke about that! I think you triggered my C55 PTSD

Opti
Opti HalfDork
5/18/16 11:36 p.m.

Gauges are 50 bucks at harbor freight, you can check your pressures then be able to diagnose future problems. Or you can probably spend less than that having a competent shop diagnose it, then repair it yourself.

The manifold hose (the big pair of hoses off the compressor) seem to leak a lot on this vintage Gm trucks, compressors seam to fail a lot and on some of the GMs they leak a lot, but I cant remember what years that is.

Good news is most of these things are cheap to fix, Ive currently done three systems on GMs of similar years and the kits are real cheap, the vette has the same compressor. So even if you find out the compressors dead and you have to change it, the orifice tube and the accumulator, you can get it and install it cheaply and have it charged by a shop, and if the compressor has ate itself and filled the system with its internals, you change the condenser also, probably an extra hundred.

Heres to hoping its a leak that's quick and easy though.

Mazdax605
Mazdax605 UltraDork
5/22/16 11:01 a.m.

So imgon's son came by this morning to help diagnose the ac leak. He used some yellow safety glasses and a black light to look for any dye that leaked. Turns out the rear lines have a fitting where they go through the rear floor to the evaporator. Looks like the o-rings there are bad. He's going to get me a new set at the gmc dealer next door to where he works, and hopefully with some new refrigerant I will be cool again. I hope this is the fix as it seems like it shouldn't be too expensive. Wish me luck.

Chris

Mazdax605
Mazdax605 UltraDork
5/23/16 6:10 p.m.

So all didn't go as planned. Small line going to rear evaporator was seized where it bolts to a block flange. As we were attempting to separate it the lines from the evaporator to the block came apart, and now I need an evaporator too. Also the line still needs to come off at the block, but we can't figure out how to do it yet. I don't want to mess up the line as it appears to be one long ass line all the way to the front of the truck. On top of all of this I noticed the universal joints were squeaking on the truck. I pulled the drive shaft, and bought new u-joints at the local NAPA. Turns out they gave me the wrong ones, or one wrong one as we couldn't get them to work. My friend brought the shaft to work and plans to get it put back together at the professional shop with maybe some stock GM universal joints. So now I have a truck with no A/C, and no driveshaft, so basically a useless truck. Joy oh joy, and oh yeah no job either. FML!!!

Chris

Mazdax605
Mazdax605 UltraDork
5/24/16 1:34 p.m.

Has anyone dealt with the issue of the rear lines being corroded where the flange and the stud holding it in place seem to be fused together? We ended up ruining the rear evaporator because of this. I bought a new evaporator, but I still need to get this part to separate. Any tips to getting steel and aluminum apart when they are corroded together?

Chris

Toyman01
Toyman01 GRM+ Memberand MegaDork
5/24/16 1:48 p.m.

You might try heat/cold cycling them. I'd use a heat gun rather than a torch. Thin aluminum will burn almost instantly. Heat it with the gun, then douse in ice water a couple of time. Then spray lube of your choice. Don't destroy the line. On a Ford, they are damned expensive and a absolute nightmare to replace. I'm betting GM lines are just as bad.

Mazdax605
Mazdax605 UltraDork
5/24/16 8:22 p.m.

Welp I destroyed the line. I have already bought a new evaporator, and installed it, but now I need at least one line. EBay has a kit designed to replace the lines for around $350 I think. New lines are all rubber to cut down on rotted lines and should make it easier to run. Problem is I don't have the money right now and it looks like getting the old lines out will be a real pain. I wonder if I could just run the new ones along side the old ones and just leave the old ones in there?

Chris

Toyman01
Toyman01 GRM+ Memberand MegaDork
5/24/16 8:28 p.m.

I would definitely abandon the old lines if they are a pain to remove. You might also look into line repairs. My E150 had a rear line fail from rubbing on the frame. New lines were well over $1000. The repair was $80. It worked for 2 years, and was still holding up fine when I sold the van.

Mazdax605
Mazdax605 UltraDork
9/9/16 5:49 p.m.

So I finally broke down and bought the replacement rear lines for the Suburban. Just in time for the cool weather!! I put them in last week, and brought them by a friends local dealer to get the system vacuumed down, and recharged. If you remember I replaced the rear evaporator, but the one I bought from the FLAPS didn't have the expansion valve, so I had to reuse the old one. It looked fine, but in trying to recharge the system the pressure went way high. My friend says he suspects the expansion valve. I priced them up on RA, and they vary from $10 or so to $40. What would you guys suggest? FWIW the compressor did kick on, and the air started cooling, but my friend was worried about the high pressure.

I'll have this thing fixed by the time the snow flies.

Stealthtercel
Stealthtercel Dork
9/9/16 6:12 p.m.

It's not all bad: at least you'll have nice dehumidified air to defog the windshield with.

Mazdax605
Mazdax605 UltraDork
9/22/16 2:51 p.m.

Okay, so now more questions. I got a new thermo expansion valve for the rear evaporator. Installed it today and had a forum members son vacuum and charge the system at his garage (Nissan dealer). Ac was blowing cool, but not cold. He suggested getting some sort of valve /screen looking thing that goes in a line in the engine bay. I walked next door to the gmc dealer and bought it for $6. Installed by friend and recharged. Now it was blowing cold for a while. For some reason the heat was then on. I believe it to be blend door issues which after getting home and disconnecting the battery for about 40 minutes and restarting the truck confirmed it. Now it blows cold, but even before I left the dealer my friend said he was certain there is still an issue as the compressor doesn't cycle, and the pressure on the high pressure side would climb over 300 when revving the engine. Any ideas why the compressor won't cycle? I drove home without the ac on, but I do know it works, but not properly I believe.

Any help is greatly appreciated.

Chris

Mazdax605
Mazdax605 UltraDork
9/23/16 7:24 a.m.

Any A/C experts in the house?

KyAllroad
KyAllroad UberDork
9/23/16 10:20 a.m.

No hep here, sorry. My 99 Burban needed a new AC compressor when I bought it so I replaced it only to find the line going to the rear unit leaked. I had the shop replace them and it's been fine since.

How goes/went the strike?

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