need some Ac help

[corvette66]

I decided to charge the AC in my 80' It's got the upgrade 134r system. Has been empty for a while. when I bought the car a few months back i was told the AC worked. The guy only had it for a few months himself so it has not been more than 5,6 months since it last worked.

The Ac pump will run, so i figured i'd try and charge it. It was empty at the time. So i charged the system (only took about 1/4 of the can) Don't know why.

So the problem is the pump will run for 3 sec then stop for 3 sec, then run for 3 sec, then stop for 3 sec. Over and over..... Very consistant. But won't stay on.
When inside the car, it blows a very little bit of cool air, hardly notice it. So it works somewhat.

Any ideas?????????

 

[muddywaters]

Sounds like your A/C is short cycling, it needs more freon or the eqiv........

 

[TMPJoe]

well it should take more than one can i believe... when changing over to R134 you have to make sure the old system is evacuated completely if I recall correctly.

don't keep trying to run the system as it is very low on pressure and not really good for the compressor when it is like that.

I would hit and AC shop and ask them to bleed the system and load it with R134 after a pressure check. If it does not hold pressure they can put a die in it to see where it is leaking.....

I have to convert mine this year as I just cannot not find freon around here at any kind of reasonable price now. I will bolt the kit up then take it to my friends shop to let the tech see if it holds pressure and go from there.

It is not uncommon to have problems when trying to use those cans and a little hose.... not at all... sometimes its the easy button and other times oh well....

i personally do not like working on AC.. too much pressure in too small a line and way too many special tools needed!

 

[bmotojoe]

I start by saying, please understand the refrigeration system and ALWAYS keep SAFETY in mind first! I would hate to hear of anyone getting hurt by over charging a system and this is easy to do without the understanding and the correct tools.
When you purchased the car did you inquire any information on how exactly the cars Air Conditioning had been converted from R12 to R134a? It’s not as simple as many make it to be on an old system by just changing a couple fittings and some “O” rings, oil change in the compressor, and evacuate the system and have a long lasting reliable stable system.
The first thing I would look for is air in the system. If your system as you say “has been empty for a while” this is not a good sign because it doesn’t become empty by itself and further more the compressor should not run at all if the low pressure cutout switch is working correctly. To check for air in the system find the sight glass located (well my 77 is) near the overflow bottle along the passengers fender. Take a q-tip and dip it in some rubbing alcohol and clean the sight glass as good as you can. Then because of the positioning of the sight glass you may need a mirror and a flash light. Start the car and A/C and watch for any signs of bubbles in the sight glass. If the system is charged correctly you should be able to see liquid flowing in the glass but no bubbles AT ALL.
I can’t stress this enough, Air Conditioning systems do create very high pressures and along with high pressures high temps are created. I know that taking a car in for A/C service is expensive but for SAFETY’S sake take a quarter at your local community college on automotive or commercial Air Conditioning to fully understand what transformations a refrigerant makes if your doing your own A/C service to your car.
Brian

 

[minifridge1138]

USE AT YOUR OWN RISK!
WORKING ON AIR CONDITIONING INVOLVES TOXIC GASES STORED UNDER EXTREMELY HIGH PRESSURES!
IF YOU FEEL YOU ARE NOT CAPABLE OF THIS, THEN TAKE YOUR CAR TO A PROFESSIONAL!
R-134a HAS BEEN KNOWN TO CAUSE CANCER (particularly testicular cancer) AND SHOULD NOT BE VENTED INTO THE ATMOSPHERE OR INHALED!
AUTHOR IS NOT RESPONSIBLE FOR ANY HARM TO YOUR OR YOUR VEHICLE!
USE AT YOUR OWN RISK!

That out of the way, charging your AC is very easy.

You need an AC Manifold Gauge. It has a gauge for the low side and high side, and a port for accessories (vacuum pump and cans of freon).

If the AC compressor is starting and stopping that rapidly, it means you're low on freon.
If you have no freon, then it won't start at all.

Before working on an AC system you need to get all of the old gas out. Take it to a shop and let them purge the system. There is a $25,000 fine for venting it into the atmosphere and a $10,000 reward for turninig people in.

Next, you need to vacuum the system. Put a vacuum on the system and let it sit for at least 15 minutes. If the vacuum holds, there are no leaks. Add freon. If the vacuum doesn't hold, then you have a leak. THIS IS CRUCIAL TO PROPER AC OPERATION. This will remove any moisture from the system. Moisture will cause your AC to operate improperly and will cause damage to the system.

If no leak, skip to next paragraph. If there is a leak, hook an air compressor to the accessory port. With the engine off, listen for hissing air. That will be the location of the leak.

Start the engine. Turn the AC on the coldest setting. Add oil. Check an AIM or shop manul for the correct amount of oil. Don't forget that most cans of freon contain an ounce or two of oil, so make sure you don't put in too much oil. Begin to add freon. In the beginning, the low side will drop to almost nothing, and then jump to around 100 psi. Keep adding freon. As you do, the low side should start to level off at about 30-40 psi. The high side should also start to level off, but probably closer to 250 psi (depends on the car).

Let the engine run for a few minutes to make sure the system is fully charged. Rev the engine to about 2,000 rpms and hold it there for a minute. Keep adding until the low side is a CONSTANT 35-40 psi. Do NOT go beyond a constant 45 psi. At this point, the high side should also be at a constant pressure.

You're AC is now charged and ready to go.
Good luck!

 

[corvette66]

awesome guys, i'll give it a try.

thanx for the help

 

[corvette66]

Got the AC working. but it only blows out of the floor vents. Is this normal or should it blow from the top vents?

 

[minifridge1138]

It should blow out of the top and bottom.
Someone else posted to the forums asking about this (it may be you, i didn't check the user).

Good luck and congrats on mostly working AC!