Any update on your system? I finally got my going after cleaning everything up, flushing, using all new orings with nylog and a new orifice tube and drier.

My system was darn clean in comparison to yours. Just light brown oil throughout, no chunks, no clogged orifice tube.

I vacuumed down for a couple hours and left the gauges and it held for a day so went to town.

Was very confused about readings but the clutch stopped cycling on its own As I got into the second can. Tried to use a generic figure of 80% of original r12 charge.

As I approached that into the 4th can I saw the high pressure side jump to about 225 with it being about 95* out. At that time my low side was 45* so I quit.

So not knowing how much you lose with a quick gauge line purge between each can I think I got about 38+ ounces in?

I thought I had read about 2.5* temp for the high side so thats why I quit. It did not seem to me the vent temps changed much at all in that last 6 ounces or so I put in?

As it stands now on a hot day like this, the system takes a couple minutes to put out cold air idling and the vents reach 55* Just enough to take the edge off inside so you aren't sweating but the impression isn't that there is cold air coming out.

Although I fixed all my vent doors with foam, I am going to install a bypass valve to stop flow to the heater core for summer just to see.

No technical knowledge on my part so no clue what to do about the refrigerant, I was almost thinking of dumping the rest of my partial can in just to see.

Also with the truck going down the freeway the temps didn't seem to be effected over idle.

And I spritzed the front end with some water and noticed each side drop pressure.

After I turn the truck off it doesn't take long for each side to equalize.

 

The pressur eequalizing is normal, sounds like you may have put in a bit too much, my lowside pressure is 38psi at idle and going down the road in 95-100 sun my vent temps are 40-43*f.

 

Mine is still going. It never got very cold but it would be a little better than rolling the windows down. I haven't used the truck much lately so I am not sure if it has leaked down or not. I will have to put a pressure gauge on it and find out. I think I need to charge it more, I had 32-35 PSI on the low side and the ambient temps were in the mid to upper 90s. I want to get a better manifold and gauges before I try to top it off. I think I was getting some bogus readings with the cheap gauge set.

 

Try revving the truck from under the hood with the a/c on, the compressor may stay engaged at idle, but once you rev it it may start cycling if you are too low.

 

At idle the compressor cycles every two seconds. Does that mean it is too low?

 

yup. the compressor should not cycle. my rides will run forever unless the head pressure gets to high.

 

I only got a little into my 3rd can before my gauges started giving odd readings. It sounds like I need to get the rest of that can in there. I'll have to order a new manifold set.

 

Yep, that is what mine actually did from the first power on with an empty stock setup system, which I didn't expect. As I charged mine slowly the time between cycles would get longer.

Only thing I haven't done to mine is adjust that lowside shutoff switch to an appropriate pressure when looking at the gauge. It was hard for me alone to rev it, watch the gauge and look/listen to the compressor. I know I haven't seen anything ice up yet, but things are dripping.

I was going to blindly buy one of those cheapo low side gauges they sell to average joe over the counter to retrofit and looked on the back and it gave a reading that said it was generically overcharged if the system was over 45psi. No clue if those things are accurate at face value.

Its heating up out here going to get close to 100 so I am going to go mess with things today after my heater vent mod and report back. I have a feeling I will be lowering the charge but we shall see.

 

I have an update. I left my charge alone and installed the valve to take the heater core out of the loop. It is 96 out and I warmed the truck up and then took some drives on the freeway.

I see a definate improvement but don't actually have anything to compare it to and am wondering if I should leave it alone?

So at idle it seemed to settle after a few minutes of running, to when the truck was very hot at about 52*

On the highway at about 55mph it got down to about 42 and when I was trying to keep up at freeway speed it was right at 40.

Note I have 4.11 gears and c6 tranny so I guess that effects rpms.

So I saw definate improvement, pounded the truck and came back to look at the gauges again and still pretty much the same. At idle its around 45psi with the high around 230. When I stab the throttle the low side drops but slowly and I can't seem to get it to drop enough to set the low cutoff switch.

High side will rise during that time going to 250+


I had replaced the blend doors and foam on mine last winter and did my best but obviously there is some risidual heat with having the heater core in the loop so I would call it a must do mod with ac.

 

If your getting those temps id just leave it be.

 

The slow drop in the low side is a concern, but not a fatal one! Have you inspected the orifice tube???

 

I get the same drop i just attributed it to the compressor turning faster, making more pressure on the hight side and sucking faster from the low side.

 

I just finished the 134a conversion on my 83 F250 last night, what a nightmare. Truck had been sitting for 15 years when I drug it out of the bushes earlier this year, so no telling how long it's been since the A/C worked. Had to replace the bearing in the compressor clutch, dryer, changed oil in the comp and flushed entire system. Orfice tube was the toughest part, it was corroded in there pretty good. I now have 42 degree air out the vents at idle @ 95 dgrees outside. Low side is around 38 PSI and high is 230 PSI.

 

You are ahead of me then, just curious as to how you charged and why you stopped adding charge when you did?

I was riding in a buddies big truck the other day in the heat and noticed when it was at its peak, the cab was just comfortable, not really noticing the vents being cold, so kind of like my truck just not the same airflow. So that made me feel good about it. Then as the temps dropped to under 90 is when I would start feeling the burn of the vents on my skin and turn them away

 

I just filled my A/C system the rest of the way. I put the rest of my 3rd can in it. At idle I was running 44 PSI. When I rev it to 1000 RPM, it drops to 27 PSI. The vents blew cool, not freezing but a lot cooler than before. I suspect if I had more airflow through the condenser and higher RPM, it would be pretty cold. The compressor also stopped cycling.