Cool/Heat: Help me make sense of my A/C routing

[cochranjd]

Hey all,

When I first got my Hawk about 3 years ago, the A/C was working and cool. Over time it stopped cooling and hasn't been cold for a few years now. Before I go about trying to do anything with a new charge, I'm going to try and identify any leaks, replace old components, etc. The only part that looked really rough was the receiver/drier, so I ordered a new one. When dropping it in the other day, I noticed that the way my system seems to be routed goes against everything I have seen online and wanted to point out what I'm talking about and see if there is something that would explain what I'm seeing (especially given that at one point the system did blow cold and I've never touched any parts of this system until recently.

Basically, my loop is as follows:

Compressor high side -> evaporator -> Receiver/Drier inlet -> Receiver/Drier outlet -> condenser intake (top) -> condenser discharge (bottom) -> Compressor low side

From everything I've seen, it should be more like:

Comp high side -> condenser intake (top) -> condenser discharge (bottom) -> drier inlet -> drier outlet -> evaporator -> compressor low side

That said, I understand that sometimes what is going on in my car will be a bit different due to the fact that it is 62 years old, so I thought I'd throw it out here and see if folks can make heads or tails of what is currently going on, before I start buying new hoses and revamping routing or doing anything crazy.

I've tried to include an attachment showing the existing setup

[stude1964]

What model are we working on? The year? Wondering where you bought a new drier. Let us know and you can PM me so I can shoot you pics of my A/C cars, Mine are all '64 models.
Rob in PA.

[cochranjd]

This is a '61 Hawk, but I have no idea when the A/C was added. It was converted to r-134a before I bought it (I believe the o-rings and a few other things were changed in that process). I just bought a vintage air drier from summit. I didn't think/know there was anything special about them. I am NOT trying to stay accurate - I want a car that will drive well (and hopefully stay cool ).

Will try to get some pictures tonight.

[64V-K7]

Compressor output - >(High side) to condenser (radiator) to Accumulator (bubble glass) to expansion valve (evaporator) --> (Interior heat exchange)---> Low side to Compressor input

[cochranjd]

That may be what is going on, but after seeing diagrams like that online (with the accumulators), I was still confused because:

1. What I pulled off sure seems like a drier vs an accumulator (see attached picture, including the part of the remaining label that says "CEIVER")
2. The drier is receiving its INPUT from the evaporator

Is it possible that somebody simply put a drier where an accumulator should have been and also happened to put it in pointing the wrong direction?

Definitely learning here, so feel free to point out if anything I've said is wrong!

[enjenjo]

That picture is the drier. I think we have a bit of confusion as far as the terms. The unit inside the car is the evaporator, and the one in front of the radiator is the condenser.

The way an aftermarket AC system is generally plumbed is the smaller line from the discharge port of the compressor, usually a dash 8 line is plumbed to the top of the condenser. The line from the bottom of the condenser< usually a dash 6 line is plumbed into the receiver drier to the "in" side. From the drier "out" side it is usually a dash 6 line into the TEV (thermal expansion valve} also know as the thermostat. The "out" side of the evaporator is usually a dash 10 line to the compressor inlet.

I think one of the things that is confusing you is there are several types of AC systems. Some systems use an accumulator with a desiccant bag inside rather than a receiver drier. This would be a GM system likely used on the later Avantis Then there is the POA (Pilot Operated Absolute) system that deletes the TEV and controls evaporator temperature with an internally adjustable orifice. and then the system you have

In all cases the refrigerant is pumped from the compressor to the condenser as a high pressure gas, from the condenser to the receiver drier/accumulator as a low pressure liquid, to the valve that controls the evaporator, then from the evaporator back to the compressor as a low pressure gas.

I don't want to discuss the CO2 refrigerant that is used in the new cars.

[cochranjd]

I'm tacking with you on terms. I only say that because the diagram in my first post is accurate based on those terms.

Here are some more pictures. One is the evaporator in the cab. The condenser in front of the radiator. The compressor (I believe it is a York type compressor) the the low and high sides marked. Also the replacement drier (mounted to the inside of the fender).

2 lines cross the firewall and hook up to the back of the evaporator unit. One of them is the line coming off the compressor marked H, the other is the line that goes to the IN side of the drier. That drier line out definitely goes to the TOP of the condenser. Bottom of the condenser definitely goes to the line marked L on the compressor.

I almost wonder if the lines are marked incorrectly.

In fact, it seems like what may be going on is:

1) L & H are marked backwards
2) L line going to the bottom of the condenser is actually H, and should be plumbed to the TOP of the condenser
3) The line going from the drier OUT to the top of the condenser should be plumbed to the BOTTOM of the condenser and the drier spun around

If 1 is correct and I do 2 & 3, then it will give me:

Compressor High -> Top of condenser -> bottom of condenser -> drier in -> drier out -> evaporator -> compressor low

And I believe that would be correct.

Does anyone know if the top or bottom port on the compressor shown in the picture is the high?

[cochranjd]

Actually, I’m assuming the condenser has different sized in and out ports so I probably can’t easily swap these lines.

[Dwain G.]

The hand drawing in the first post has the system running backwards. It also omits the expansion valve which is where high pressure changes to low pressure before entering the evaporator.
Isn't all this kinda moot anyway? You're still going to have to take it to a shop for evacuation, flushing (maybe), testing, recharging.

[cochranjd]

The system had no pressure in it when I checked it (and I've removed/replaced the drier). I have a friend who has redone his old cadillac's AC and my plan was to put a vacuum on the system and make sure it holds (or identify places I need to fix) and then eventually recharge it with his help.

I have yet to find an expansion valve (another part of the overall mystery of what is going on here). I'll get some pictures later, but the lines in my initial diagram are hoses - there is a hose that has one end connected to my drier, one end to the back of the evaporator. A line coming out of the evaporator and going to the compressor...a line from the compressor to the condenser and one from the condenser to the drier...

Unless I'm just completely missing something, I don't see anything else.

I will say the place where the 2 hoses attach to the back of the evaporator are covered in some sort of thick material - almost like old tape or some sort of adhesive....if there is anything under that, I don't know.

Will try to get more pictures later.

Appreciate everyone's help!

[Ron Dame]

That diagram is so back asswards. Now I admit, I'm no expert on anything including A/C, but somewhere those lines cross, perhaps at the firewall and going to the evaporator, but it just can't cool in that configuration. And there has to be a TXV or orifice tube somewhere in the system. Am I right?

[enjenjo]

The condenser is mounted upside down, likely it can be flipped by tweaking the brackets slightly. The receiver drier is plumbed backwards. just rotate it 180 degrees and reinstall. The TEV/TXV is mounted to the inlet of the evaporator inside the car, and covered with the tape like insulation to keep it from sweating and dripping water inside the car. The picture of the compressor head has the lines marked wrong. The top line is high pressure gas in, and the bottom is high pressure liquid out.

That is an old system and has the R12 hoses yet. R134 can leak right through those hoses. You really need to change those hoses. I have the correct hose in stock and can send you what you need at wholesale price plus USPS shipping. PM me for details. In the 1980s I installed several hundred AC systems in commercial trucks.

[cochranjd]

That all makes total sense to me enjenjo and seems like the most likely scenario. Here's a picture of the back of the evaporator and after looking at it, I'm guessing you are also correct that this is all just insulation around my expansion valve.

I'll PM you later this evening (or first thing tomorrow) about the hoses!