It's that time of the year again, where I have to choose between roasting in my 89 or going deaf with the windows down. So, I've decided to fix my AC. When I bought it, there was just a little bit of pressure in the system, probably a psi or less. I did borrow a pump and pull a vacuum, which held, but in reading and researching and pricing out parts, I dont want to have to buy a compressor if I don't need to. So, has anyone torn down a failed compressor to see what went bad? I'm just curious if its something yhat could be tested for, to know if my current compressor is healthy or on its way out.

In all honesty, I'll probably end up buying a new one anyway.

 

Your question is kind of like asking "How long is a piece of string"? Do you have more info from the previous owner? Was the compressor operational? How many miles? Has it been converted to R134A? I have only had two compressors apart and in both cases, the pistons had separated from the swash plate and grenaded everything. There is not much to them really but from what I was able to determine, they work fine until they don't. Nothing inside to really "service". My advice? Get a new compressor and be done with it. Also, if the existing one has destructed itself, a new condenser is needed and a complete flush of the lines and evaporator.

 

Captain Spaulding would say it's "Too goddammit long"
Previous owner gave me a box of parts he got when he bought it. Inside, among other things, was a bag of AC orings. I don't know for sure, odometer broke at about 67k Again, I dont know. There is a r134 adapter on the low side, but no sticker stating it had been converted Many years ago i had a York piston type compressor apart, but i dont know much about these. Theres no oil around the seals or pulley, so no clue if its good or not. I did jump the low side pressure switch and it cycled, seemed to sound ok. A new condenser isn't a big expense, so I'm not worried about that.

Thanks for your input.

 

If it has a R134A fitting on the suction, then one can assume a retrofit has been done. No other reason to put it there. Evacuate, hit it with a couple of cans R134A and see where it goes.

 

An 89 has a 10PA20 Compressor. I've owned (3) C4 with 10PA's and I haven't had major trouble with any of them. (The 92 smoked the clutch coil. Common.)They're pretty good. The clutch coils seem to be a service item, but not many peeps report having had to change the compressor itself. Leaks at the shell or seal don't seem to be a problem. Rock Auto shows availability, but with a $580 price. For $50 of R134, I'd take the risk that the existing compressor is ok. If it has to be replaced, it's only $50 of R134 lost to find out.

I'd pull the orifice tube and inspect it for metallic debris. If there isn't any, or very little, I'd deem the compressor serviceable. If it turns, and builds pressure at the outlet just by turning it by hand with your finger over the outlet, it is probably a decent bet that it will be ok. I'd replace the accumulator, as many o-rings as are accessible, put 3 ounces of Ester Oil in each of the accumulator and the compressor, evacuate, pressure test, charge and run it.

 

Thats what i was thinking, I don't know it it had ever been charged though. The compressor doesnt look new, but doesnt have any signs of seal leaks. I have more questions, but I'll google them first.
:edit: looks like all ac oils are the same color. I think I'll pull a sample to see if it looks new or used, and pull the orifice too to see if it caught any compressor junk.

 

Densos rarely fail, the compressor case seals can leak with age as can the shaft seal.

134A conversion **** often do too, probably a combination of leaks from the schrader valves and maybe the comp case. Hell, the condenser could have taken a rock and punctured it.

 

Denso's don't usually fail if they have the correct refrigerant oil charge. If it runs smooth and quiet it is probably fine. Seals leak with age. Denso seal kits are cheap and easy to install and no special tools are needed. Adding refrigerant is easy. Getting the correct amount of the oil is the hardest part. I like to clean all of the old oil out and start over so I know exactly how much and what type is in the system.

 

A better question would be 'what a/c compressor which is modern, known reliable, affordable, easily scavenged from limitless supplies(that I can get multiples of for cheap), and proven to be an easily integral with my existing combination'

Rather than worrying about any specific existing compressor, especially aging or outdated, time would be more well spent adapting modern reliable compressors with plentiful supply low cost bonus

Cleanliness is key to operation. Vacuum system, replace drier, seals, cover the system when its opened to keep dust/debris contamination out, make sure add compressor oil as needed when replacement

 

Well, 86-91 Mercedes I6 W126 cars had Denso in serpentine belt fashion but were not the 10PA20, they were the 17. Might have to flip the top plate and measure bolt spacing....unsure how the vehicle would react to a smaller displacement but it pulls down my long wheel base car just fine, obviously far larger cabin than the Vette. My dead 750iL did too, it was 06/88. Pal's 525i E34 had one, heck look at W140 Mercs.

May give you some leads.

 

I'm surprised there isn't a 5.3L ~2005 Truck alternator / AirC compressor conversion system yet, those things going 250k miles or whatever and around scrapyard/ebay @ the cost of a around used tire

or *cough* maybe a sign to just swap to an LS *end cough*
05' the L33 is aluminum block... light like an LS1 but three times stronger internals/block roughly

 

The Gen 3 trucks at least used a 10S17 or 20, my Suburban (11/00 which is a 5.3/60E) with rear HVAC uses the 200cc unit...which is why I cannot see the Vette needing such a large displacement unit. I bet it would be fine with a 10PA15 even. After 200k of daily use, those compressors are tired. Mine is beat.

L33s use the same crank, rods are just LS2/LQ9 rods. The floating pin units with the dot on the beam. My '02MY Escalade for parts had the LQ9 engine, basically an iron block LS2 with open chamber heads (317s over the 243s).



Anyway, I am with the others to charge it and see what happens. Seal kit is probably $30-40 for the unit if needed. ACkits or Coldhose. Hell, Sanden may have a drop in if you care to look.

 

Hey thats a really good idea, something that can fit without a retro-argument of components. You really seem to know about compressors, thats interesting.

I bet there is something MODERN which is the key I think to reliability and easy setting up for success in general. Weld some lines and go just don't neglect a pressure switch for the high side I think

I'm using a 240,000 miles LM7 from 02' escalade in a daily at 600rwhp gasoline(started at 180k) - was just supposed to be a test engine from 2017 to 2019 but it wont tire out!

 

I was planning an LS swap a year ago, be decided that I needed to finish other projects first, then collect parts for the sawp. The last thing I want is for my Vette to be in pieces, and my attention elsewhere.

 

Opinion?

Definitely metal particles. I didnt check to see if it would build pressure, I'll try that tonight if I have time.

 

In doing some research, I found out the ZR1s use the 10PA17. I wonder if the larger compressor was used due to the greenhouse sized rear hatch, and the smaller one in the ZR1 due to a larger engine? If the ZR1 A/C worked well, then I'd assume it would be fine in my 89.

 

System suffered 'black death'.

It might run halfassed post a flush, charge, and fresh FOT. That is your call if you want to gamble with it as it is already summer for most of us.

 

I think the length of the body is different for the two displacements. The distance between mounting centers will be different. The displacement is determined by the stroke of the pistons. Larger displacements have longer stroke, and thus longer center sections.

The ZR-1 has the same evaporator size as the 'base' car, but the air-flow through the lower 1/3 on the outlet side is obstructed by the relief put in the housing to clear the cam cover on the LT5. This 30-ish% reduction in air-flow reduces the heat transferred into the evaporator, and thus can utilize a smaller displacement compressor. The shorter compressor may have also been a consideration for packaging on the LT5. I have no idea if it was.

The ZR-1 also has the special "Solar" windshield with the laminated tinting to reduce the sun-load on the interior. OEM's have standard specifications for Air Conditioning performance. To meet these requirements, the ZR-1 received the Solar windshield because of the reduced cooling capacity of the A/C system. I've owned a ZR-1; I'm not so sure I would evaluate the A/C performance as "worked well".

In a CCOT A/C system, the larger the displacement, the better the refrigeration system performance at low engine speed in hot ambient conditions. Like at idle in stop and go traffic in July. At higher engine speeds, the clutch begins to cycle to maintain the desired evaporator pressure/temperature.

Stick with the 10PA20.

EDIT/ADD: I just saw the pic of the orifice tube. Yes, there is some metal, but it isn't a lot. The outlet side screen has residue build up that may be affecting performance. I'd do the 'turn by hand suction test' and if it passes, I'd replace the orifice tube, probably replace the accumulator 'just because' and add 4oz of Ester oil to the new accumulator and 2-3oz to the compressor. Recharge it and see how it does. As I said in my earlier post, a new compressor is $580+. 3 cans of R134 is about $50. If the compressor is bad, you're out $50 to find out. If the compressor is still serviceable, you saved $580. << I'm frugal. This is my thinking. And again my experience is that the 10PAs don't have problems other than the clutch coils. Cheers.