AC charge question

[ajcbgray]

My AC (still R-12) seems to work well except for the fact that it will only cool the air to about 15degF below ambient temperature. I've had the car since December and it hasn't gotten worse, so I don't think I'm leaking.
I want to top it off, but don't know how much r-12 I'll need. I have access to the small cans, but not the hoses (unless I can find that one that was floating around the shed of my last house... don't know if it made the move). Can anyone tell me how much I might need? Anyone in the Atlanta area that has the hoses that could help me out filling it up (or anyone want to mail me a loaner set)?
thanks,
ben

[sixto]

How can knowing how much there should be help you top off? Do you know how much is in there now? Maybe you're asking about pressure rather than weight or volume?

If it's cooling but insufficiently, I'd start with cleaning the condenser and evaporator.

Sixto
87 300D

[ajcbgray]

Well, I was hoping someone who has worked on their AC and had similar lack of cooling would be able to give me a ballpark of how many pound cans of r-12 I might need to refill my system and get it cooling up to par. If someone has the the pressure specs that would be great too.
ben

[vstech]

the specs should be on a sticker on the front of the car, but they will tell you the total charge, not how much you need to top off what is already in there.
listen to the advice you are getting. the FIRST thing to do if it's not cooling adequately is clean the condenser and clear any and all debris from the fins.
NEXT you verify the aux fan is engaging at it's setpoint,
THEN and ONLY THEN should you worry about adding in refrigerant.
also, IF you find that after this is done, refrigerant is needed, you will also require additional mineral oil be added. When freon leaks out, it takes a percentage of oil out with it.

[daw_two]

Originally Posted by vstech

the specs should be on a sticker on the front of the car, but they will tell you the total charge, not how much you need to top off what is already in there.
listen to the advice you are getting. the FIRST thing to do if it's not cooling adequately is clean the condenser and clear any and all debris from the fins.
NEXT you verify the aux fan is engaging at it's setpoint,
THEN and ONLY THEN should you worry about adding in refrigerant.
also, IF you find that after this is done, refrigerant is needed, you will also require additional mineral oil be added. When freon leaks out, it takes a percentage of oil out with it.

So, I'm off to now trace the AUX FAN circuit..........oh, these cars, how we LOVE the challenges they throw at us.....

[ajcbgray]

no leaks that I can find (UV dye in the freon, checked with a black light), aux fan works fine, condenser fins are clean. Freon flowing past the sight glass is milky looking which I assume is from tiny bubbles in the freon (please correct me if I'm wrong). I just took it for a spin and under way it was blowing about 56 deg. F (ambient is 80). The insulation has fallen off the hard line over the front of the engine... I figure replacing that will buy me a few degrees.

[JimmyL]

Again, vstech is giving excellent information! Nice.....
You need gauges at this point to tell you what the pressures are, then based on that and ambient temperature you can add freon based on what the system is telling you.
Autozone has a tool loner program, but they don't always have gauges that will work with R12 fittings. [I have their gauges out in the garage right now] Some have removable R134a fittings that will allow you to connect to R12 connections, some do not. Somehow you simply have to get gauges on the car.
Oh, did you check for dye in the condensation that drips out of the bottom of the car through the tranny hump? If evap has a leak some dye usually mixes with the condensation and will illuminate.

[Cr from Texas]

It's not the best way but I've had some success with charging R12 based on the sight glass. Just enough to remove bubbles and make it clear.

Cloudy? I'd be concerned that the dessicant in the drier has gotten loose in the system.