A/C Discoveries & Problems

[1987 GMC Jimmy]

Finally replaced my compressor along with accumulator and o-tube. A few observations that I made (some obvious and some that took a little bit of research/ingenuity) and problems...

• It was prudent to replace the o-rings since everything was apart.
• The flush seemed like an important step to get a fresh start on the amount of oil in the system.
• The o-tube was stuck so I heated the pipe and and blew it out with 135 lbs. of compressed air. It shot out like a bullet.
• My NAPA accumulator did not want to cooperate. I don’t know if it was the thread pitch or what, but I had to fight it to avoid crossthreading, and it didn’t want to tighten all the way. Finally got it after some massaging. I’d get a different one if I had it to do over.
• Turn the compressor some once buttoned up to move oil into the system. Also, it recommends to let it sit clutch down to submerge the seal(s) in oil. The typical setup in a R134a system calls for 8 oz of PAG 150.
• Make sure all your hoses on your vacuum setup are nice and tight otherwise, you won’t get up to your 28-30” of Hg on the gauge.
• When you purge the air when you go to charge, turn the Freon cab upside down so it flows easier.

Problems:

• Once I got Freon squirting out of the purge valve, with my gauges still holding vacuum, I started the truck up and turned the A/C on. Then I went to open the low side valve, and my low side pressure jumped up to an initial 75 pounds and slowly kept going up, but I couldn’t get the Freon to go in. The compressor never kicked on. I verified my low pressure switch was good, and I jumped the clutch with the engine off, and it clicked. What the hell was wrong here? I had to take the equipment back so I did a quick revacuum, and shut the whole mess down. Of all the parts that went into this, this should have been the easiest. Thoughts? I might just take it to town and have someone else do it with their equipment.

 

[75gmck25]

You should unplug the low pressure switch connector and use a jumper between the connector terminals to make sure its not the problem. There is also a low temp probe/switch in the condenser, which shuts the system off when condenser temp is below about 35 degrees, but this should not be a problem. You need to get that compressor to turn on before you can get it to pull in more charge.

If you jumper the low pressure switch and turn on the A/C at the controls, it should click and engage the compressor. If you can't get that far, you need to do more troubleshooting of the wiring. Also verify that the adapter you screw into the can is working properly. Most of them are very cheap, and sometimes you don't get good flow out of the can when you open up the valve.

I also put the can of R134a into a pan of hot water sitting in the engine compartment, to "encourage" it to vaporize and fill the A/C. Make sure you keep the can upright, since at this point you want only vapor to go in. As it fills you will definitely feel the can getting very cold. Pulling in too much fluid R134a will cause the compressor to slug/lock, so leave it upright to pull in vapor. To speed up the charge process it also helps to put a large box fan in front of the grill so that you push more air through the condenser.

Commercial A/C machines push the R134a charge into the system, so in most cases they don't even worry about the compressor coming on until they are down to the last few ounces of refrigerant.

Bruce

 

[1987 GMC Jimmy]

You should unplug the low pressure switch connector and use a jumper between the connector terminals to make sure its not the problem. There is also a low temp probe/switch in the condenser, which shuts the system off when condenser temp is below about 35 degrees, but this should not be a problem. You need to get that compressor to turn on before you can get it to pull in more charge.

If you jumper the low pressure switch and turn on the A/C at the controls, it should click and engage the compressor. If you can't get that far, you need to do more troubleshooting of the wiring. Also verify that the adapter you screw into the can is working properly. Most of them are very cheap, and sometimes you don't get good flow out of the can when you open up the valve.

I also put the can of R134a into a pan of hot water sitting in the engine compartment, to "encourage" it to vaporize and fill the A/C. Make sure you keep the can upright, since at this point you want only vapor to go in. As it fills you will definitely feel the can getting very cold. Pulling in too much fluid R134a will cause the compressor to slug/lock, so leave it upright to pull in vapor. To speed up the charge process it also helps to put a large box fan in front of the grill so that you push more air through the condenser.

Commercial A/C machines push the R134a charge into the system, so in most cases they don't even worry about the compressor coming on until they are down to the last few ounces of refrigerant.

Bruce

I did jump the low pressure connector, and I got a nice click when turning the key on with the A/C on. The can tap did seem kinda squirrelly because I didn’t think I’d have to hold the cab upside down and cycle the valve a couple times to get it to flow. It absolutely would not come out with the can upright. Unfortunately, I don’t have any other tap to compare this one to, and I haven’t done this before so I don’t have prior experience to reflect on.

 

[Colin]

I found the adapter I had to get for these new "self-sealing" cans to be a PITA!!!

 

[1987 GMC Jimmy]

I might just have to take it to town to have someone with commercial grade equipment finish it up. I did literally everything by the book and then some. The Freon should have flowed like water, but it didn’t.

 

[1987 GMC Jimmy]

Figured out why freon wouldn’t flow. The valve on the inside of the adapter was shot. It’s getting freon now, but it’s coming straight out the back of the compressor. What a stupid design. The flange on the suction and discharge sides are at different heights so you have to level it out with these seals that are different thicknesses.

 

[CorvairGeek]

I've wondered what sadistic, crack head at GM came up with this B.S. I had to sort it out when I found the late 90s Delphi service compressor for my Caprice.

You must be registered for see images attach

The sealing O-rings had previously been standardized for years.

 

[1987 GMC Jimmy]

I've wondered what sadistic, crack head at GM came up with this B.S. I had to sort it out when I found the late 90s Delphi service compressor for my Caprice.

You must be registered for see images attach

The sealing O-rings had previously been standardized for years.

This is silly. It says I need C and E, and I’m using B and E, and B is a better fit because it fills up the diameter of the recess where C wouldn’t. My kit didn’t come with C so I’ll order it separately, but they are the same thickness and inside diameter. I’m going to experiment tonight with a vacuum pump and see if I can establish a seal. There’s no reason it shouldn’t...

 

[CorvairGeek]

IIRC, I may have not used the suggested 'correct' combination either. I bought some sort of '4 Seizens' kit and used what made the hose block fit evenly. I know i left out the metal inserts.

 

[1987 GMC Jimmy]

IIRC, I may have not used the suggested 'correct' combination either. I bought some sort of '4 Seizens' kit and used what made the hose block fit evenly. I know i left out the metal inserts.

Mine didn’t come with any inserts. Also, are you familiar with the Delphi/Harrison V5 compressor? I’m debating converting that system on the Olds to R134a or leaving it R12. The right way to convert entails getting every last globule of mineral oil out, and I really don’t feel like doing that on a transverse engine setup unless there’s a plug on it.

 

[CorvairGeek]

You can see the green seal on my high pressure side.

You must be registered for see images attach

Very familiar with the V5. It does have a drain plug, as it has an oil sump, just like the old A6 compressor. The entire oil charge goes in the sump. They are known for leaking out the front seal, which can be replaced with the double lip seal, AC Delco part number 15-30948, GM part number 2724954. Sometime into the 90's, GM quit painting the V5 compressors black. If you have a natural aluminum one, they also leak from the body seal, as they body corrodes under the body o-ring.
V5s don't cycle, as they use a refrigerant control valve to regulate flow and evaporator temperature. No need to worry about the difference between the R12 and R134a valves.

 

[1987 GMC Jimmy]

You can see the green seal on my high pressure side.

You must be registered for see images attach

Very familiar with the V5. It does have a drain plug, as it has an oil sump, just like the old A6 compressor. The entire oil charge goes in the sump. They are known for leaking out the front seal, which can be replaced with the double lip seal, AC Delco part number 15-30948, GM part number 2724954. Sometime into the 90's, GM quit painting the V5 compressors black. If you have a natural aluminum one, they also leak from the body seal, as they body corrodes under the body o-ring.
V5s don't cycle, as they use a refrigerant control valve to regulate flow and evaporator temperature. No need to worry about the difference between the R12 and R134a valves.

And the yellow seal on the other side, that’s what I did. I probably should have just done the Sanden conversion. My Caprice seems to have an actual pre-Compressor Works R134a unit, and it works like a charm. I know those were only produced for a couple of years, but that seems like the ideal setup for R134a that will last a while. If it’s one of these pesky Four Seasons units, I’d be pleasantly surprised, but the labeling suggests otherwise.

So, I’d just need to drain the mineral oil and put 8 oz. PAG 150, replace the front seal, mine’s black, and add 75-80% of the 24 oz. charge. Doesn’t sound horrible. If the access wasn’t front the wheel well, it’d be a piece of cake.

 

[CorvairGeek]

I couldn't recall what the suction seal was called / color, but I could still see the green washer / seal! Would love to know what or if, there was any logic to the seal change.

 

[1987 GMC Jimmy]

Okay, so I tried this again, and low and behold, the green seal and yellow seal did it. I just had to be extra careful to make sure everything was seated properly. It did hold 28” of vacuum, and no freon is escaping that I can tell. Everything got sucked in once I backed off full open on my refrigerant tap. I didn’t blast the Freon in there either, which I think is important to avoid overwhelming the compressor. I lost a few ounces out of the four 12 oz cans that I bought so I’m gonna check back tomorrow and see if I need to add a couple of ounces to seal the deal. It’s blowing pretty crisply, but I need to verify with my infrared thermometer. Compressor is as quiet as a mouse when engaged minus my v belt being a little wiggly under load, but it makes a chittering sound when the clutch is disengaged. Something in that clutch assembly wasn’t adjusted to spec at the factory. Any ideas???

 

[CorvairGeek]

"it makes a chittering sound when the clutch is disengaged. Something in that clutch assembly wasn’t adjusted to spec at the factory. Any ideas???"

Sounds like what is called 'clutch drag'. They are supposed to be about a 20 thousandths gap (a standard business card works well), but metal particles between can cause them to make noises. The V5 clutches are known for this in particular, but I don't know why. As the gap will open up in time, I wouldn't worry yet, unless it is truly dragging and not fully disengaged.
Do make sure the clutch isn't being fed some low voltage when it should be disengaged, that may be trying to partially engage it. Never know with age / wiring, and the 'high quality' parts with which we are stuck. I could see a funky cycling switch staying fractionally engaged with Murphy's Law.