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98 suburban, what do I need to look out for?

70monte on Mon July 19, 2010 9:48 PM User is offline

Year: 1998
Make: Chevrolet
Model: Suburban
Engine Size: 5.7L
Refrigerant Type: r134a
Country of Origin: United States

I'm going to be fixing the AC on this vehicle for some of my fiancee's relatives. They have taken it to a couple of shops where one told them the compressor is leaking and it will be $1,200 to fix it and the other shop said the compressor is not leaking and recharged it and now its not cooling again. This shop replaced the low pressure cycling switch and the switch on the high side of the hose manifold.

I looked under the hood and could immediately tell the compressor has been leaking. Extremely dirty and oily and bracket underneath the compressor is wet. Truck has 168,000 miles on it and it looks to be the original compressor. I have a couple of questions about repairing this vehicle.

I don't think its had a catastrophic compressor failure so I'm hoping it doesn't have a lot of debris in the system.

I'm not familiar with the duel air systems on this vehicle. I have done two 98 C/K trucks but these were my own vehicles and I replaced most of the AC systems to avoid problems down the road. I don't know how much they want to spend on parts so replacing some things may not be an option.

1. For just a leaking compressor, what other than the compressor, accumulator, and OT do I have to replace. All I have is a flush gun which is not very powerful.

2. Can this type of condensor be flushed and does it need to be if the OT looks pretty clean?

3. Manifold hose assembly. This set has the inline muffler so it cant be flushed. Does it need to be replaced or can it be reused?

4. What do I need to check on the rear air part of this system? I have heard that this part is hard to access and is usually rusted together.

5. This system takes 64oz of refrigerant and 11oz of oil. How much oil should I put in the system if I can't access the rear part of the system or if I leave the condensor in place?

Any other tips on fixing this system. On my own trucks I replaced everything in the systems other than the evaporater and line going from the condensor to the evaporater so I'm not sure what is acceptable to do if you don't replace everything. Thanks for any advice.

Wayne

GM Tech on Tue July 20, 2010 8:46 AM User is offline

These are the ones I re-seal almost daily---All new belly o-rings and a new shaft seal-- for under $300---out the door...Got a 97 Blazer out there today with same issue.....

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

70monte on Tue July 20, 2010 1:21 PM User is offline

GM Tech,
Thanks for the reply. So on a system that only the compressor is leaking, you only repair the compressor and leave every thing else alone? Do you replace the accumulator and OT.? How much oil do you add back into the system.

When I go to recharge, do I need to have the rear system on max and the fan on high?. I'm very familiar with the front part of this system, just not the rear part. I really don't want to mess with the rear expansion valve or any of the rear plumbing if I can help it. How often do the rear expansion valves need to be replaced.?

They brought me the Sub today and I looked at it a little closer. The compressor is the only thing that looks like it has leaked. The owner is the original owner and says that the compressor has never been changed and did not make any noises. The odometer shows 122,000 miles on it but he says it has 168,000 miles on it so I'm not sure what is correct. Thanks for any other advice.

Wayne

Cussboy on Tue July 20, 2010 3:02 PM User is offline

On my '94 Suburban dual air with a leaky compressor this spring, right or wrong I replaced only the compressor and accumulator with new. My rear expansion valve failed last year (clogged or stuck closed), but no big deal (even in Arizona) as the system cools great now. I replaced the accumulator because in my case the system had been without refrigerant for several months due to the leak (why fix in fall if a tree might fall on it and wreck it, it's only worth $2500). Since the compressor didn't seize or make any noises, and past experiences with replacing the orifice tube didn't show ANY particles, I didn't address that at all.

I did add full amount of R134a (64 oz.) even though the rear wasn't working, must fill the system (or physically block off the plumbing to the rear).

In the 10 years I've owned this 1994 Sub, the compressors have only lasted a few years each. They get used 95% of the time, but dual-air systems are just very tough on them, read GM Tech's TSB in other posts.

70monte on Tue July 20, 2010 4:01 PM User is offline

Cussboy,
thanks for the info. How much oil did you add to the system for just replacing the accumulator and compressor.?

The owner said that the rear air worked fine before so I'm hoping that it still will.

Does both front and rear AC need to be on max when recharging?

The r134a capacity listed on the accumulator is 3lb 8oz, so 56oz. Should I stick with 56 or go to 64oz?

I ordered the replacement compressor, accumulator, OT, Pag oil, and some gaskets from Ackits today so hopefully I can get this fixed this weekend. I ordered the Seltec compressor but they called and said they didn't have it in stock so I got the Sanden one instead.

Thanks again.

Wayne

Cussboy on Tue July 20, 2010 8:25 PM User is offline

Quote
Originally posted by: 70monte
Cussboy, thanks for the info. How much oil did you add to the system for just replacing the accumulator and compressor.?


My R4 compressor (1994 Sub) had ZERO oil in it, even when I tipped it and turned it by hand (it was not seized). I went by the NAPA chart at http://napabeltshose.com/news/index.cfm?location_id=1078&id=1517&show=newsitem so I added a complete 8 oz. bottle of PAG-150 oil that contained UV dye. The chart said my dual air system had capacity of 11 oz. oil total. That's also where I got the 64 oz. R134a from for mine; mine didn't have any sticker, and I'm the second owner.

Quote
Originally posted by: 70monte

Does both front and rear AC need to be on max when recharging?


I would run both. Our local radio mechanic here in Phoenix insists to ALWAYS have the rear AC on (with blower medium or higher)when the front AC on, to prevent any liquid refrigerant from reaching the compressor. It seems to make sense to me. See FAQ at marksalem.com for that, don't remember which FAQ number though.

Quote
Originally posted by: 70monte

The r134a capacity listed on the accumulator is 3lb 8oz, so 56oz. Should I stick with 56 or go to 64oz?


Welcome to the world of GM, conflicting information and confusion about parts. In your case I'd start with 56 ounces and see what pressures are, and how the cooling is. It would be a ton easier to add 8 oz. later than to try to remove 8 oz. !!!!

Quote
Originally posted by: 70monte
I ordered the Seltec compressor but they called and said they didn't have it in stock so I got the Sanden one instead.


Sanden is a good compressor, have Sanden on my Mazda truck, tons better than the R4 compressor mine takes. I bought my accumulator "elsewhere", and had to go to CarQuest to get an O-ring to match the one already on there between accumulator and front evaporator. The two that came with the accumulator were too thin, needed a thicker one for that one fitting. Cost 25 cents.

70monte on Tue July 20, 2010 10:31 PM User is offline

Cussboy, thanks again on the clarification for my questions. I'll start with the 56oz of refrigerant and go from there. I thought maybe later on, someone discovered that 64oz worked better.

The amount of oil has me most concerned since I'm hopefully not going to be tearing apart the entire system. I guess I will go with the 8oz you suggested unless someone gives me a good reason not to. There is no telling how much oil has leaked out from the compressor. The first time I looked at the vehicle, it was pretty wet under there. Not so much today.

I've heard that the Sanden compressor is one of the preferred replacements so I'm not worried about it. I've just used the Seltec in the past and have had good luck so far with them. Thanks again.

Wayne

slockm on Tue July 20, 2010 11:44 PM User is offline

HA! Sounds like we're in a similar position:
I've got a 98 Yukon that I've worked on. I couldn't break the rear expansion valve loose and it was a royal pain to get to. I replaced the accum, comp, OT, and condenser. I opted not to flush the system since the OT was clean and I was replacing most of the components. If I remember correctly I charged 5 cans (60 oz) but more or less watched the readings as I neared the 5 can mark.

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I know nothing...seriously

Cussboy on Wed July 21, 2010 8:57 AM User is offline

Quote
Originally posted by: 70monte
The amount of oil has me most concerned since I'm hopefully not going to be tearing apart the entire system. I guess I will go with the 8oz you suggested unless someone gives me a good reason not to. There is no telling how much oil has leaked out from the compressor. The first time I looked at the vehicle, it was pretty wet under there. Not so much today.

Drain the oil (if any) from the old compressor, and measure how much there. Then take the new compressor and drain that into a clean container, and measure that, and that would ne OK to re-use. I've seen compressors come with zero oil, some with too much, I sure wouldn't trust "Gomer" at the factory. So 8 oz. is likely OK, but that should be total oil volume in the compressor, that's why it's smart to measure what's in there first, even if it states shipped with no oil.

Even with rebuilt compressors, the AirPro rebuilt Sanden for my '88 Mazda truck contained PAG oil, and I needed R-12 mineral oil, so I flushed several times with mineral oil before adding its correct amount and installing. Then co-worker bough AirPro rebuilt for his '90 import, and that came with mineral oil already in it. Go figure. Luckily, I can differentiate at work in 5 minutes between the oil type (infrared spectrophotometer, if anyone is interested).

Chick on Wed July 21, 2010 10:10 AM User is offlineView users profile

If you have front and rear air, your oil capacity is 11 ounce front air only is 8 ounces...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

70monte on Wed July 21, 2010 11:07 AM User is offline

Quote
Originally posted by: slockm
HA! Sounds like we're in a similar position:

I've got a 98 Yukon that I've worked on. I couldn't break the rear expansion valve loose and it was a royal pain to get to. I replaced the accum, comp, OT, and condenser. I opted not to flush the system since the OT was clean and I was replacing most of the components. If I remember correctly I charged 5 cans (60 oz) but more or less watched the readings as I neared the 5 can mark.

I'm going to pull the OT and see what it looks like. Hopefully it will be clean. I don't want to mess with the rear air components if at all possible. I'm undecided if I should replace the condenser or not. Do you remember how much oil you put in the system?

"If you have front and rear air, your oil capacity is 11 ounce front air only is 8 ounces..."

I realize that this system holds 11 oz but if I'm not taking the entire thing apart, how much oil should I add?

I will try draining the old and new compressor but on both of my 98 chevy trucks, nothing came out when I tried draining them so I'm not too hopeful that I will get anything out of this one. Thanks again.

Wayne

Cussboy on Wed July 21, 2010 11:16 AM User is offline

Wayne - in mine the brand-new compressor (Delphi R4) contained no oil at all. For my '94 dual-air Sub I added an entire 8 oz. bottle of oil (which already contained some UV dye) to the compressor, then turned it about five revolutions by hand before installing the compressor.

I did all mine in one day, took about half day including the evacuation, vacuum hold test, adding the R134a. In my case, I did not have to "tweak" the R134a amount later.

70monte on Wed July 21, 2010 11:24 PM User is offline

Thanks again for your help. I just want to make sure I'm not putting too much or too little oil in the system since the only components I'm replacing are the compressor and accumulator and this system holds quite a bit of oil. I'm still undecided on replacing the condensor because I have not taken out the OT yet. I'm going to do that tomorrow.

I know the correct way to do this repair is take everything apart and flush but getting the back stuff all apart is probably asking for trouble. I don't want to risk ruining the rear lines if I don't have to. I know they are expensive.

I did get the old fan clutch off and mounted the new one to the fan blades but I will wait to install it after replacing the compressor since it gives me a lot more room to work with it off. Thanks again.

Wayne

70monte on Thu July 22, 2010 2:08 PM User is offline

Well, I pulled the OT and the screens were as clean as a whistle. Actually, the cleanest one I have pulled. The OT itself didn't look new so I don't think its been changed. I don't plan on changing out the condensor or the lines now. I'm just going to replace the compressor and accumulator, pull a vacuum, and recharge.

If none of the other connections look like they have been leaking, should I just leave them alone and not put new o-rings in? I typically do replace all of the o-rings but this vehicle has a lot more connections than what I have typically worked on. I wasn't planning on messing with any of the rear connections, just the ones in the engine compartment.

Wayne

Cussboy on Thu July 22, 2010 2:30 PM User is offline

I wouldn't mess with connections that weren't leaking and weren't disconnected.

70monte on Thu July 22, 2010 8:15 PM User is offline

I ended up replacing all of the O-rings because when I got to looking at some of the connections a little better, the two connections in the engine compartment that go to the rear air were very dirty and slightly oily. To get to those though, I had to disconnect the one line that goes into the lower part of the evap since it was on top of the two lower rear air lines.

I inspected all of the lines going under the truck all the way to the back and did not see any leakage. As long as both evaps are good, I'm probably ok.

Hopefully I will get the parts tomorrow so I can finish this up.

Wayne

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