Hi again everyone,

Well, the elky is running decent now but when I tried out the A/C it started blowing out hot air. My dads friend is an a/c repair man and had two cans of R-12 laying around. We added them into the system and found out that the high pressure side was at 130 psi and the low pressure side was pulling a vacuum of -20 psi. To his knowledge, the low pressure side should be reading 30-35 psi.

What would be causing a vacuum to be on the low pressure side?
Could there be a blockage somehwhere?
Also, it seems to be leaking freon out of the fitting in the low pressure hose side. Where and who makes these high and low pressure hoses for these cars. I have had no luck in finding anyone to repro these.

The elky that I am working on is a 70 Elky SS 396 with factory R-12 air. I would like to try and keep it original with R-12 but will convert over to R-134 if only a necessity to get it fixed if R-12 parts are no longer avail.

Any help would be greatly appreciated.

thanks,

Brian

If the leak is bad enough to hear or see you are probably loosing it faster than it can get back to the comp. Low or empty systems will run in a vacc on low side and still have some sort of head (high side)psi.

Now that you have ran the system with a leak you will need to recover whats in there or just walk away for a while...replace the hose, drain and refill the comp with ester oil (for 134a) nitro(dry nitrogen) test repairs (also helps flush moisture) pull system into vaccumm with a vac pump, refill as a liquid in the high side with proper poundage.

it is possible that the oriface tube may be plugged also.... but having the leak large enough you dont need a detector...the low charge theory is more probable the cause.


you can get the hose made at an industrial hose supply or a local Thermo King dealer. just take the hose incase you have reuseable ends or so they can match your ends. Maybe car dealers are making there own hoses now not sure...

some people skip the nitro and vac. but if you are looking for long system life this a must do.

chris

No orifice tube on a 70, it has a TXV. Check with Hinshaws Chevelle Parts for the hoses and other parts you might need. With the system low on freon, it takes almost 4lbs, those readings are expected.

Hello again,

Just went outside today and check on the elky's A/C charge. With the engine off, the readings were 75 psi on the low pres. side and 60-65 psi on the high pres. side.

With the motor running and the A/C unit on, the low pressure side still had a vacuum of 20 psi and the high pressure side was at 90.

One additional thing that I noticed was the expansion vavle was getting frost on it when the system was on.

Also, it appears that the vavle on the high pressure hose seems to be hissing a very little bit. Do they sell new valves to replace bad ones? It looks very similar to a valve core on a tire stem.

My question now is:

-should the expansion valve be getting frost on it?
-If there is a restriction blocking the flow of freon from moving, would that cause a frost build up on the metal part?
-Where can I get a new valve core for the high pressure hose line?

Any help would be greatly appreciated since I would like to have the A/C system working for a long trip I will be making Sept. 19th.

You might try www.ackits.com (http://www.ackits.com) forums for some threads in-progress re: reurrecting stock R12 systems and/or convertings to R134a. The converison is not quite the cheap easy process some people claim. Good Luck!

My $0.02

1 You have a restriction at the expansion valve
2 Your high side fitting is leaking and MUST be replaced. Very easy to do and a good shop should have the tool to replace the core without opening the system.
3 system is low on charge. Pressures should be close to 200 on the hi side and 30 on the low for a R12 system
Your original post stated 130 hi side and -20 low side.
Did you actually have a neg reading on the low side?? :eek: if so you have a major obstruction

Yes, unfortunatly, that was the reading I got on the low pressure side at the POA valve. If the expansion valve is not opening, would this cause there to be a vacuum caused on the low pressure fitting? The vehicle was sitting for quite a while and the previous owner I assumed never used the A/C so the expansion valve from lack of use could have frozen in place therefore causing the major obstruction? I have a new expansion valve that I got from an auto parts store and when I have the system apart, I will be replacing all of the O-rings to prevent any problems after it is all back together.

think that could be my problem?

Thanks,

Brian

The service of AC is not to be done by non licensed individuals. You can not repair any of the components without the release of freon which is expensive and against the law. You have to repair the restriction, so get the system evacuated of freon, then repair the expansion valve, check the expansion screen for pluggage, ther should be one, replace the dryer and fix the leaking core on the fitting. Then have the system checked for leaks prior to having the system evacuated and recharged with the recovered freon previously removed.

Engineer,

My friends dad is a fully liscensed and certified HVAC and Mobile Air Conditioning system repair and installation person. He is the one who is going to be evacuating the system of R-12. He is the one who will be filling the system back with R-12. The only thing that I will be doing is replacing the expansion valve and cleaning the filter screen. If I wanted to break the law, (which I know the fines since I work for a police dept) I could have easily just vented the R-12 out into the air. But since we (meaning my friends dad and me) just put 4 cans of R-12 into the system and found a leak, we want to recover and reuse the R-12 that we put in there. Relax, everything that I am doing complies with federal, state, and local government laws.

P.S.- No trees were harmed in the reply of this posting.

you missed the point, it does not take 4 cans of freon to find a leak with a halogen leak sniffer nor does it seem likely a certified mechanic would not look for a restriction. Filling a unit after a leak was found is not SAE procedure. You never fill a system that has not been used for a while unless there is significant pressure on the system to start with.

We were not aware of the leak until we filled the system. This is the first time the AC has been used since we got the car in Feb. aside from the initial blowing of warm air on a trip. Once we had the system back up to normal pressure, we then noticed that the expansion valve was frosting up and that the high pressure schrader valve was leaking when we took off the dust cap the next time. My dads friend is not a auto mechanic however he is a HVAC technician who took the mobile air conditioning servicing class and passed it getting his certificate to work on mobile air conditioning systems.

In order for the compressor to work in the el camino, there needs to be enough refrigerant in the system to enable the safety to let the system work as it would normally. Therefore we had to add the R-12 to the system to get the dye circulating through out the system.

Im not trying to defend what my friends father did but he has been doing this for the last 35+ yrs and he knows what he is doing. Granted, I might not post or remember every single thing that we did on the car or in the order that we did it but everything that has been done has been under his supervision so no laws are broken or the system explodes.

Brian, your friend can put in a new valve core, in fact a regular tire valve core will work fine.

He can pump the R-12 into a container to save it then you can check the inlet screen on the TXV and see if that's where the restriction is.
If the screen is not restricted, then I would say you have a bad TXV

There is always some refrigerant loss during transfer because it's pretty hard to get it all back out of the recovery machine and hoses so if you only added 24 OZ, you probably won't have much saved, depending on how much was already in the system before you started of course.

And I might ad if he dumped refrigerant into a system that had none (which I doubt any A/C tech would do) then the refrigerant is now no good because it is contaminated.

Good luck

If memory serves, 4 cans is not enough freon 12, that is 48 oz and the system probably takes about 60 oz of freon, so you still had a low charge after 4 cans were installed in the system.

According to the factory service repair manual, the correct amount of R-12 that should be in the system is 3 1/2 to 4 lbs. The original sticker on the compressor says 4 lbs. So total between the first time and second time we added a total of 4 cans of R-12 plus the oil. I assume we had enough. Could I be wrong? Certainly. My main thing now is I have to get the system evacuated then fix the expansion valve, replace the o-rings since the system is drained, and then check for leaks and reinstall the R-12.

Generally, today's freon cans hold 12 oz of freon and 16oz make a lb.

Just wanted to add that you should also replace the drier when you replace the expansion valve, otherwise you may find the valve sticks again.

Ordered the receiver/drier today from my local Chevy parts dept. $45 dealer cost. Should be in 3-4 days or so.

Well, I got the receiver/drier in and it looked nothing like the old one. supposedly, it is a factory service replacement. I didnt like it not only cause it didnt look original but looked completely different than the one I had. I am trying to keep the el camino 100% original since everything on the car is original from the factory right now down to the bias ply tires with only 43,000 on the odometer.

Ok,

System was evac'd and here is what we found. The metal screen in the expansion valve was clogged with black crud. We were able to clean the screen out since we couldnt get it out to replace it with the new one. We are trying to keep this car 100% original since it is all original as it is right now down to the bias ply tires with only 43,000 miles on it. We are going to charge the system with nitrogen and see if there is any leaks on monday. If no leaks and system works fine, then we will recharge it with R-12. Hopefully the exansion valve is still good and the cause of the -20 on the low pres. end gauge was cause of the blockage in the filter screen.

There is a good chance that the crud in your screen is dessicant from the drier that's floating through the system. You might check with a NAPA store in your area & see if they have any old NAPA Temp Products catalogs that will have pictures or illustrations of the driers. Then you can find out if it's still available. It would be a bad deal for you to go to all the trouble of recharging the system just to have it stop up again in 30 minutes running time. You also might want to get an orfice screen removal tool to get the old screen out. They're pretty cheap & easy to use. Another thing, although this isn't an original part, I would add a filter to the suction line so that the compressor won't be damaged if some junk breaks loose.
BL

Oops, I just realized that you have a expansion valve & not an orfice tube type system, so disregard the part about the tool. graemlins/clonk.gif
BL

ok,

here is the good and bad news with the elky. The system was taken apart again after it was evacuated and here is what I found after it clogged again. Expansion vavle filter screen was packed with this brownish blackish crud. I started taking the system apart and checking for any other restrictions. Took the receiver/dryer out and shook it upside down and on its side... guess what came out... stuff that resembled brown dirt. Hence the desiccant was coming out of the inside of the receiver/dryer. Found a place down in FL that rebuilds/restores your original A/C system parts including the receiver/dryer. Cost for one they have in stock redone or yours is $58. which isnt bad since it is original equipment.

I will keep everyone posted as to how it comes along. Chances are I will be getting it either in the winter months or in a month or two depending on time.

could all that crud be your compressor breaking down inside ? or from the hoses rotting on the inside ?

Did you buy that 69 383 4 speed Charger in philly
I sold one about 2 years ago all original in need of rear 1/4s and some other stuff..just curious after seeing the sig

No, that wasnt me. I got mine from Ebay from a guy Long Island.