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.

Any help would be greatly appreciated.

thanks,

Brian

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.

Any help would be greatly appreciated.

thanks,

Brian
Twenty psi is not a vacuum. Sounds like you're still low on charge. Should be seeing higher than 130 on the high side. Your system holds 3 - 3.5 lbs.

Most a/c shops can rebuild your hoses, if you can't find one, send them to me and I'll rebuild them for you.

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.
Brian
Twenty psi is not a vacuum. Sounds like you're still low on charge. Should be seeing higher than 130 on the high side. Your system holds 3 - 3.5 lbs.

I mistyped the low pressure side. It was not 20 Psi. it was reading below the 0 mark on the negative side 20. Therefore it was pulling a vacuum. My friends dad who works on A/C systems said that there might be a blockage causing the low pressure side.

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.
Brian
Twenty psi is not a vacuum. Sounds like you're still low on charge. Should be seeing higher than 130 on the high side. Your system holds 3 - 3.5 lbs.

I mistyped the low pressure side. It was not 20 Psi. it was reading below the 0 mark on the negative side 20. Therefore it was pulling a vacuum. My friends dad who works on A/C systems said that there might be a blockage causing the low pressure side.

So, it was actually pulling 20 inches mercury, which is a vacuum.
You either have a restricted expansion valve or POA valve. Best to replace them together if you aren't sure how to diagnose them independantly. First thing would be to feel the lines going in to each of the two and feel for the cold spot (the restriction.)

The POA valve was cold and the one line going into the expansion valve was cold also but then after a short time of putting in two cans of R-12, the small amount of frost on the outside of the metal lines went away and it got warm. I am more leaning towards the expansion valve being clogged up. My dad and I were able to get an expansion valve from an auto parts store for R-12 for our system. At the same time we also got an O-ring kit to replace all of the o-rings while the system was evacuated.

I have recently noticed that wherever the hoses and metal lines get connected together has been having an oily substance where the fittings connect to each other. Could the system, possibly from being over charged since there was a restriction in the lines and the pressure wasnt circulating, have blown out the o-rings also? Might this explain the low pressure fitting leaking due to too much pressure?

The POA valve was cold and the one line going into the expansion valve was cold also but then after a short time of putting in two cans of R-12, the small amount of frost on the outside of the metal lines went away and it got warm. I am more leaning towards the expansion valve being clogged up. My dad and I were able to get an expansion valve from an auto parts store for R-12 for our system. At the same time we also got an O-ring kit to replace all of the o-rings while the system was evacuated.

I have recently noticed that wherever the hoses and metal lines get connected together has been having an oily substance where the fittings connect to each other. Could the system, possibly from being over charged since there was a restriction in the lines and the pressure wasnt circulating, have blown out the o-rings also? Might this explain the low pressure fitting leaking due to too much pressure?

What makes you think it was overcharged? Regardless, the fittings are probably leaking due to being 33 years old. Your expansion valve is a generic 1 ton, externally balanced type. All valves today are 134a and R12 compatable. Should have been very easy to find. Change your drier while you're doing the repairs.

What I was meaning by overcharging the system was that if the expansion valve is causing a blockage, the compressor is compressing the 4 lbs of fluid building up the pressure causing a higher than normal operating pressure which could have caused the o-rings to fail.

Where can I get a drier from? And how much do they usually run?

What is the main job of the drier in the A/C system? Im not too familiar with the working components of an Air Conditioning system.

What I was meaning by overcharging the system was that if the expansion valve is causing a blockage, the compressor is compressing the 4 lbs of fluid building up the pressure causing a higher than normal operating pressure which could have caused the o-rings to fail.

Where can I get a drier from? And how much do they usually run?

We only know for sure that you have 2 cans of freon in your system, since that's all you put in, not four. The fact that you only have 130 psi on the high side gauge reading indicates it isn't overcharged, (well, depending on where the high side port is located anyway.) I'm pretty sure it's before the expansion valve on the liquid line, or on the discharge hose at the compresser.
Anyway, the compresser doesn't compress fluid, it compresses low pressure vapor in to a high pressure vapor.
O'rings generally fail because they have either been over tightened, under tightened, installed incorrectly, or just plain old and dried... rarely because of an overcharge. Your system should have a thermal limiting switch mounted at the compresser on the clutch power wire...unless it's been bypassed. It's job is to sense high pressure in the system, via high temperature and open the electrical circuit thus shutting the system down in case of an overcharge.

What is the main job of the drier in the A/C system? Im not too familiar with the working components of an Air Conditioning system.

See: How an a/c system works (http://elcaminocentral.com/modules.php?name=News&file=article&sid=52&mode=thread&order=1&thold=1)

Originally we added a can of oil charge to the system. Then we added 2 cans of R-12. About 2 days later we added 2 more cans of R-12 and got the same reading. Prior to us adding the R-12, there were no visible leaks in the o-rings. I dont know if there was any freon in the system or not when we got the car but the guy said it blew out cold air. When we got the car it was in Feb. and when we turned on the A/C it seemed to blow out cold however it was fairly cool out that day that we tested it. I must be losing freon someplace but it doesnt seem to be any large puddles of oil or freon anywhere. Any suggestions or insight would greatly be appreciated.

Originally we added a can of oil charge to the system. Then we added 2 cans of R-12. About 2 days later we added 2 more cans of R-12 and got the same reading. Prior to us adding the R-12, there were no visible leaks in the o-rings. I dont know if there was any freon in the system or not when we got the car but the guy said it blew out cold air. When we got the car it was in Feb. and when we turned on the A/C it seemed to blow out cold however it was fairly cool out that day that we tested it. I must be losing freon someplace but it doesnt seem to be any large puddles of oil or freon anywhere. Any suggestions or insight would greatly be appreciated.


I have recently noticed that wherever the hoses and metal lines get connected together has been having an oily substance where the fittings connect to each other.



Might this explain the low pressure fitting leaking due to too much pressure?


Yes, repair these leaks, find the restriction and repair, evacuate and recharge, and check leaks using a leak detector....your a/c friend should have one.

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 can get new schrader valves at any auto parts house.
If the expansion valve is frosted, it is either stuck shut, or has crud in the orifice...this explains the 20 inces of vacuum. Replace the valve.

Wow, thats great to hear that the schrader valve is still available. Thanks for everyones help with this. I have the expansion valve and now just need to get the system evacuated and recovered.

Thanks again for everyones help. I will keep everyone posted as to how I make out.

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.

next along the problem chain....

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.