My 95' leaked out a couple of years ago and I'm in the process of getting the car running again. It's mostly sat in my carport being started up once in a while. My plan is to restore it to its former glory. I am replacing all the hosed from the compressor, accumulator, dryer, etc, and the dryer itself, since it's been exposed from the leak in the compressor hose for a couple of years. I have the shop manuals but it assumes I have the $1500 machine that the Chevy techs have/ had access to back in the day, so it's a little confusing. Do I just put R-134 in, or do I need to put some sort of oil/ lubricant before I do this. Any conversions needed? I've seen some post referring to R-134a conversions but I've seen others that say the 95' doesn't need it. I'm about ready to go rent a pump and valve set. I am so ready to get this thing going again!

 

The 95 is a R134 System, basic stuff, no conversion

Are you replacing a known bad part, or just shot gunning a bunch of stuff just because.

Non usage can cause seals to leak. But if you don't know where a leak specifically is, I would not rip it apart yet.

If this was me, I would first put a set of gauges on it and see if there is any pressure at all. Because you may just need a recharge and once you open the system it then needs to be evacuated. Not a big deal you just need a pump, hoses (gauges) and some experience.

The system holds about 2 cans of 134 (forget exact amount) when empty but will take less on a re-charge.

Once you open the system and replace hoses and accumulator you need some oil and it turns into a much larger job rather than a re-charge.

So if a system is opened, a vacuum pump, gauges and Freon is all that is needed. No special equipment but additional skill is.

And on a car that sat for couple years might not be a bad idea to add some dye just in case a leak has to be tracked down.

 

Since you're going to go through the hassle and time to replace all the hoses AND the Receiver drier - two suggestions.

1. Replace the orifice as well (it's a sub $20 part, and it can get clogged up - it MAY even be included with the new receiver dryer).
2. When you (or a shop) goes to charge the system - the first step is to pull a vacuum on the system. Before starting to put in the R134a - add in a little dye, that way if a leak does develop - you can find it fairly easily.

With respect to actually doing the refill - you can buy a gauge set for about $50 and a vacuum pump for about $100. You might want to see if there is a local place that will do the charge for $50 or $60. The actual R134a is running a bit less than $10/lb, so your car will use less than $20 of R134a and the machine is pretty much automatic - hook it up - enter the amount of Freon to be dispensed, and hit GO. Come back 20 minutes later and it's pretty much done.

 

I had traced the leak to one of the hoses coming out of the compressor, I could see it it leaking after I tried to refill it. I would rather pay someone to do this but after the hurricanes, and the pandemic, it has been difficult for a single guy like me to take the car in anywhere because of the backlog, etc. I just want to make sure I'm not forgetting anything.

 

Just some personal experience for the OP and additional information.

Not too long ago I replaced the evaporator and the accumulator on my 94. So this is fresh in my mind as exactly what has to be done.

1 - As said by me and above, put in dye. But it takes a while to show up unless there is a massive leak. And it has to circulate which means adding enough Freon to run the compressor and that’s almost a re-charge. If evacuation leak down test fails, you usually don't put in Freon, it's not ready. The dye is for the future cause some leaks take a while to show up. You fix it all first before adding Freon.

2- The orifice tubes are real cheap. I bought a five pack for a few dollars from AZ. The tube is in the evaporator. I borrowed a orifice puller from AZ but on our cars it physically will not fit in there to get it out. I actually made my own just for this purpose because the pipe is real close to the evaporator. And also, if you try to get it out with a long noise and break it, you are in deep deep poop. If it comes out easy, that would be nice.

I used my tool to install it in the new evaporator, but when I took out the old one from the old evaporator, the screen was real clean. So use you own judgment.

 

You are ABSOLUTELY correct about the way the charge machines (that most stations use) work. You hook them up - and they pull a vacuum on the system for a predetermined amount of time (typically 15 or 20 min), then they turn the vacuum pump off - and the machine monitors the level of vacuum. If there is a leak - the machine sees the vacuum isn't holding, and essentially "locks out". If the system passes the vacuum leak test - the machine then adds the appropriate amount of refrigerant to the system, and verifies the high side and low side pressure are within something resembling "normal" values.

If however, we have a leak, and the machine "locks out" the inability to add some refrigerant makes finding the "leak" (particularly a smaller leak) difficult. The two primary ways to find a A/C system leak are by injecting dye and running the system (then looking for the dye), or by using a refrigerant sniffer while running the system. Of course - in order to run the system - you need to have enough pressure in the A/C system to convince the pressure switch to run the compressor (or you have to bypass the pressure switch - which sounds easy - but in some cars the Compressor is controlled by the car's computer - and it is difficult to convince the compressor to run when the pressure is too low).

The above is why SOME Pro's that do a lot of HVAC work - ALSO have a standard charging manifold and a vacuum pump - so they can manually inject dye, and manually push in refrigerant - so the compressor will run and circulate the refrigerant - so they have a halfway decent chance of actually finding the leak - so they don't just blindly throw parts at the problem.