Air conditioner troubleshooting and part search

I have a family vacation planned and the missus approved use of the hearse for transport, but she really would appreciate if the a/c worked! Y'know, for the baby.

Anyway, I got down under the hood with GM service manual in hand and followed the flowshart diagnostics. I knew the heat and blower worked, so something else on the a/c side wasn't working. Using the chart, I've tested and confirmed that the compressor doesn't cycle, but clutch engages when jumped, and the compressor itself isn't seized and the belt is in good condition to turn everything over.

The next item on the list was to check the pressure to see if the refrigerant was low. I'd planned on converting to R134 anyway, so I'd bought the fittings and starting hooking them up to my a/c manifold gauge. Low side fitting is on the receiver/drier and screws in no problem. Moving over, lo and behold, I torqued the high side schrader valve threads a little too much for vintage aluminum and broke the sucker clear off the hose assembly. I know, I know, serves me right, eh? The good news was that there was absolutely no pressure in the lines at all, which sort of confirmed my suspicion that refrigerant was low or it had developed a leak and escaped years ago. In the year I've owned this the a/c would never kick on but I've been happy with 4/60 air. The pressure switch probably wasn't telling the compressor to do its thing.

To even continue troubleshooting and partially charge the system to find a leak, I need to replace this part! I've now turned (to my inexperienced mind) a somewhat straightforward repair into a crazy debacle of trying to replace this fractured part. The service manual calls the actual aluminum canister piece of the hose assembly with high side fitting the 'muffler'. I've had more luck searching for 'a/c hose assembly' or 'a/c hose manifold'. I've already taken a swing and a miss at an aftermarket part fitting from Amazon. I'm heading to a u-pull yard tomorrow to check out some vintage GM hulks to see if they have what I need in the same alignment, but I'm not feeling confident I'll succeed.

Any tips? It's an '89 Buick LeSabre/Estate Wagon, V8 Olds 307. The a/c compressor is a radial-type Harrison 622. Are there other cars with the same setup that I could interchange? I know Pontiac Safaris are pretty close, same engine. Will anything with a 307 work?

I attached pics of the assembly I'm looking for and one of the part I ordered that doesn't fit. Y'know. As a joke.

 

Yeah, that's the high and low service hoses (that's what I know them by). You should at least be able to walk into a parts store with the old one, and have them ID it and get a part number; but, you can also google "obsolete GM A/C parts," and I'm sure there are places that carry those. As far as interchanging, it's only going to be those wagons and their sedan counterparts with the 307, as the setups on each of those hoses for each GM RWD car at that time would've been engineered for each of those body types, i.e. a hose assembly for a G-body won't be the same as a hose assembly in a B-body.

 

That's not a part one would change every day. Most cars went to their graves with this original part still mounted. I'm sure, if a reputable GM dealership were to do a search, there should still be this particular part still sitting on some shelf, if you need it in a hurry

 

Thanks for the tips. I had good luck at the second boneyard I tried, so no trips to service counters for me, yet. A less-crusty Pontiac Parisienne had exactly what I need and I found another option from a Cadillac that's a slightly different style but might fit as a backup. Fingers crossed they don't leak.

Supposedly there were four other wrecks that could be interchanged at that yard. To my horror, some lunatic with a sawzall had come through and butchered everything in the a/c systems. They basically only take the condenser and leave the cut hoses, receiver, and evaporator. Isn't there some kind of junkyard code to leave the other usable parts for someone who might need them next? Like, you want the condenser, great, but damn, don't damage the rest of the fittings and stuff attached, eh?

I'll try to update after the install and see how the conversion progresses tonight. Here are the service manual troubleshooting pages, they might help someone in the future.

 

Why would the aftermarket part not work? I realize it looks different, but it appears like it would be functionally equivalent.

 

I have a Cadillac with a 307 and that exact same setup of suction\discharge lines. If you can't locate a correct style fitting, you can locate, say, a 1989 Chevrolet Caprice\Impala with a 307 engine...

Four Seasons 55475. $49 from Rock Auto ;-) It doesn't look identical but it will work just fine.

OR... you can go back to the salvage yard (as you did). Grab the connection off the back of one of the compressors that the guy sawzalled up (as long as all he did was cut through the rubber and not the metal) that looks closest to yours, then go to an AC shop and have a new line made up using your old one as a template. In reality you *should* do that anyways if you're converting to R-134a as the new barrier hoses are so much better than the original hoses, and you did have a leak in your system anyways. I bought a crimper and die setup for doing all of our classic cars because I have a fleet to maintain and it's so much easier to do that than trust a 30+ year old hose you pulled off your (non-functioning AC) car or a junk yard car. You should also replace the cores themselves as the high side fittings are known for leaking...

But the fitting you grabbed from that car should work fine provided the hoses are in good shape.

 

classic air in tampa fl stocks parts, kits and a whole lot of knowledge

 

Good answer!!!! It doesn’t even have to be an ac shop, we used to go down the road to a place that did hydraulic lines mainly but they had all the right stuff. Tell them how long the hose needs to be and give the the metal parts and they’ll make one up for you. Sometimes this was cheaper than buying an actual part

 

hoses are easy to make if you can find the fittings. napa is a good source . some places rent the crimper and some ends do dot even need crimping

 

I buttoned everything back up after flushing, changing the o-rings, receiver, orifice, and compressor oil to new stuff. After I pulled a vacuum for a few minutes the pressure goes back up pretty quickly, so I have some more leak-checking to do. My suspicion is that I used the wrong size rings and it leaks from fittings, or the line I pulled just leaks through the hose. I'll also make sure my gauge isn't leaking (hazard fraught). I was really hoping to avoid having to replace the cores, though... I like the idea of having new hoses made at a shop if the price is right. Thanks for the Rock Auto part#. If all else fails I'll order that and try it.

I'm sure functionally it would work, but the fit was all wrong. The muffler didn't reach around the compressor and the hoses were the wrong length and the fittings were bent the wrong way and the threads didn't match.

 

Can you put some dye into the system to check for leaks?

 

The compressor ester oil has dye in it, but it would only leak out when the system is pressurized. I'm going to double check all the fittings that I messed with again as well as the compressor manifold rings and vacuum it again. If I have to partially charge the system to find a leak, I'll probably get a sniffer tool to help locate it.

 

I saw you got it on Amazon. You should at least be able to return it relatively easily I don't order many car parts from Amazon, but when I do I usually double or triple check the part number across a couple of other websites to make sure it is correct. I don't trust their application chart for parts.

How quickly does the vacuum go away once you close the valves and turn the pump off? I had a Chevy Express van I was working on that had an evap core leaking so badly it would lose all vacuum in less than a minute. It was so bad you could hear the vacuum leaking while the pump was running.

Did you replace the shcrader valves themselves? They are easy and cheap enough to change in addition to all of the o-rings you already changed that I would just go ahead and replace them. I also wouldn't overlook the condenser. It lives a hard life in front of the radiator and may have taken a shot from some road debris along the way.

Did you replace the receiver/drier as well?

 

Yeah, the seller on Amazon was pretty understanding and apologized, they just go by what the manufacturer said will fit. I did try to cross reference with a few sites, but they all looked about the same, too.

If my gauges are working correctly, it leaks fairly quickly. Not as fast as a minute, but I'd think within 5 minutes it would be back at 0. If the leak doesn't go away after I check my work thoroughly, I'll look deeper at the evap and condenser cores. I did replace the receiver/drier.

 

The local pawn shop has 2 or 3 of those “sniffers”. I don’t need it at the moment but I know I will. Just can’t bring myself to fork over the cash