Air Conditioner Recharging

JonathanS · #1 05-22-2005, 08:33 PM

What is the proper refrigerant pressure in the A/C system of a 1996 LSi?

I seem to have an A/C leak in my recently purchased SVX When I inspectd it prior to purchase about a month ago, the A/C wasn't working. The seller said that it hadn't been recharged in several years, We agreed that she would have the A/C recharged and inspected to make sure that's all it was. The shop put UV dye in the system and reported that there were no leaks visible. When I closed the deal and picked up the car, the A/C was working fine.

About two weeks later, the A/C stopped working. Since the shop that did the original check is over an hour's drive from my home, taking the car back there would involve taking a day off from work, so I can't realistically take it back there.

Today, about a week later, I purchased a UV lamp but didn't see any signs of a fluorescent dye. I then bought an Interdynamics recharge kit with guage and also some UV dye. I added the UV dye (thinking that perhaps the garage's dye had been worn/washed away) and let the system run for about 10 minutes, per package instructions. Still no leaks visible.

I did check the refrigerant pressure, however, and it was low, at around 18 psi. I recharged it to about 27 psi. I think the 19 oz. refrigerant canister ran out at that point. The Interdynamics packaging said that the "filled" range is from 25-45 psi at 75-85 degrees F. Since it was about 68 degrees when I filled the system, I figured I had added enough.

Did I? I don't have a shop manual, and I couldn't find any A/C specs in the owners manual.

I plan to check for signs of fluorescent dye and keep track of the A/C sytem pressure a couple of times this week. I would appreciate input from fellow owners on the following:

-- What is the proper A/C system pressure?
-- Why am I not finding leaks? (I am guessing that there is an internal leak, say in the compressor or elsewhere, that is collecting the dye internally.)
-- I also picked up some Interdynamics two-part A/C leak stop. Part one is supposed to fix metal-to-metal leaks and part two is supposed to fix rubber leaks. Is there any reason not to just dump it into the system?

Thanks in advance from a novice A/C tech ...

thundering02 · #2 05-23-2005, 01:00 PM

If it hasn't been charged in several years then it may still have R-12 system which is illegal to produce now you'll need to spend the money to convert to r-134a and then have it charged.

#3 05-23-2005, 01:40 PM

Look at the sticker in the car.

Earthworm · #4 05-23-2005, 01:49 PM

His is a 96 so it will have R134 as opposed to R12. Only 92's has R12.

SVX-FF · #5 05-23-2005, 03:45 PM

Quote:

Originally Posted by Earthworm

His is a 96 so it will have R134 as opposed to R12. Only 92's has R12.

Well thet just sucks for us 92'ers dont it.

Steve

Earthworm · #6 05-23-2005, 06:24 PM

Quote:

Originally Posted by SVX-FF

Well thet just sucks for us 92'ers dont it.

I've got my retrofit kit...I just need to install it. (read: lazy)

#7 05-24-2005, 12:11 AM

Quote:

Originally Posted by SVX-FF

Well thet just sucks for us 92'ers dont it.

Steve

It only sucks if you need to fix it. If it's working properly it's colder than 134a.

#8 05-23-2005, 04:53 PM

1. you may have a leak in the portion of the system which is in the dash. if so, it is a pain in the butt to get to.

2. my mechanic does NOT like the leak seal stuff because he has been told that it can much up his discharge a/c recharge system. i presume it works for small leaks, but if a tech ever has to drain the system you may have a problem of having the shop refuse to do it if they know you have the stop leak in the system or have the moral issue of not telling them and harming their equipment.

michael · #9 05-23-2005, 06:08 PM

Refrigerant type and capacity are on a sticker on the radiator support.

JonathanS · #10 05-24-2005, 08:13 PM

As noted, my 1996 a/c system is R-134a.

How do I check the part of the a/c system inside the dash?

gl1674 · #11 05-26-2005, 12:00 AM

There is no easy way to check whether the amount of refrigerant in the system. The only way to do it reliably is to evacuate all refrigerant from the A/C, weigh it on scales and add the missing amount. Pressure gauge readings will show if the system is grossly undercharged or overcharged, but they will not show if you have only half of the R134 in the system.

What pressure gauge shows is a function of compressor delivery volume (increase RPM and the readings will change), outside temperature, inlet and outline line temperatures, position of the evaporator valve - just too many variables to figure it out properly.

To help you with your search for leaks, R-134 is agressive on rubber seals - it is possible that they've started leaking. If the engine compartment is reasonably clean, you might be able to find leaks even without the UV stuff. Compressor oil is still oil, albeit a special one. Check for wet greasy residue around all hose connections, especially on high pressure side - from compressor to condenser, filter and evap valve.
Another possible culprit is the seal in the compressor shaft - check for oil traces on the bottom of the compressor.
Check the rubber A/C hoses themselves - they may leak through.

You also might have a hole in the condenser and it would be much more probable than a leak in the evaporator - condenser is in front of the radiator and catches stuff that flies into it from the road. Just keep looking for black greasy spots.

As for stop leak stuff - I personally stay away from it.