Thanks Dave, The compressor is brand new. I used three cans of 12oz but I've got another I can try to get in there. Should I try to put more in? I did replace the orifice valve. I'm going to check the evaporator for clogging on the side right now.

 

If it was me I would try another can after I checked the evaporator that is was clear.
Why I say that is I am only seeing 50 to 75? PSI on the gauges and the high side should be higher than that when my system is blowing cold.
That and the compressor not running all the time when on max AC fan on high.

Also was there anything left in the cans? I have a bucket of really hot water to set the can in or set the can on the hot exhaust manifold to heat it up to push out every last bit.
I heat it then shake it to feel how much is left and heat, shake till it is empty.
Did you also add dye to the system just in case you have to trace a leak? It would not hurt just in case.
Dave ----

 

 

Making some progress. The evaporator doesn’t look too bad. Looks like an average amount of debris removed but fortunately I’m not seeing any of that “cement” buildup.

Have you tested it yet with the improved airflow through the evaporator?

I got to wondering if the problem could be as simple as a misadjusted pressure switch. Remove the connector and you will see a small screwhead between the contacts. CCW 1/8 of a turn lowers the setting roughly 2 PSI (equivalent to 2 degrees.) Try a small adjustment CCW and see if that brings down the low side pressure. You can’t really hurt anything trying Just keep track and return to the existing setting if no improvement.

Also, have you gone for a test drive yet or is this all stationary in your driveway? If the airflow through the condenser is marginal (not uncommon while parked), you may get better results driving. Obviously you can’t read pressure while moving, but use a little thermometer in the center vent for the final word

 

I tested it stationary and it didn’t seem like it changed too much. I’m going to drive it in to work tomorrow and we’ll see.

what readings should I look for if I adjust? Am I just trying to get the compressor to stay on?

 

When discussing adjustments to the pressure switch, lots of guys speak in hushed, fearful tones, as if the truck will blow up and rain molten metal on passersby if done incorrectly. We still don't know if it does need adjustment. It's just one possibility, that's all. Or it may be seized up and needs replacement, still unknown.

Properly adjusted, you'd want to see maybe around 35 PSI on the low side. The actual number on the gauge is not the primary factor, though. Once you get the system cooling properly, and I'm sure you will, the whole point of the adjustment is to keep the evaporator slightly above freezing. You don't want ice to build up, as that will restrict airflow. It also acts as an insulator, reducing heat transfer. A little bit of ice is normal, but you don't want much.

The way to adjust it is to watch the duct temperature on a test drive at a relatively constant speed. If too low and ice is accumulating, you will see very cold temperature at first, followed by a gradual warming. That's your clue to turn the screw a tiny bit clockwise to increase the pressure and resulting temperature to decrease ice formation. Repeat as needed.

Conversely, if the system never gets cold enough in the first place, turn the adjuster counterclockwise to lower the pressure and temperature. You've got to be careful, though, as many other factors can cause reduced cooling. That's why I suggested trying a small adjustment and see if that helps. If so, repeat as necessary. If no help, return to the original setting and continue troubleshooting for other causes.

Don't overlook checking for a slipping clutch, as previously detailed. I think that is far more likely than a misadjusted pressure switch.

I'd also suggest getting a chef's thermometer to stick in the dash vent. This will help keep an eye on overall performance. I have a Taylor 6091N. I like this one because the needle is straight up at 40F. I have my pressure switch adjusted for 38F discharge temperature(done by trial and error, don't remember the exact pressure value). It's easy to spot the reading without having to squint to read the numbers:

 

Simple answer, yes. You can judge the cooling by how much the compressor stays on. On a hot day, with the A/C levers on "normal" it should be drawing in hot outside air and the compressor should stay on all the time. I personally would not put any more refrigerant in it, 2 cans should get it to start cooling, 3 cans is plenty.

Sounds like you had some leaking problems right after you got it going, so I would be concerned if it still had enough refrigerant in it. Like everything else, it may take a few false starts to get a older system working again, the reason I like R134a because it's cheaper than R12.

 

On the low PSI switch I could not adjust it as it takes a backwards flat blade screwdriver and needle nose pliers would not fit down in the plug.

I did find a switch that was used with 134a and had the same plug shape but did not last long, think 1 summer, so went back with the R12 one and been working since.
You can tell when the coil ices up as the air flow gets lower so I turn the AC off and let the warm / hot air blow thru till it gets a little warm then turn the AC back on.
The only time this is a problem is spring & fall when it is not that hot but want the windows up and AC on cause even on low it may ice up.

If the vents are putting out 35*- 40* and the pump is turning on & off you may be good as it will keep the coil from icing up.
The line into the evap coil should be cold and have condensate on it if it is humid out.
You can also use a jumper wire to bypass the switch if it will not pull in 134a because the pump will not run.
I still dont like the high side PSI as it looks too low in my book.
Dave ----

 

Hmm, that sounds like your switch has an oddball adjuster. On mine, it's just takes a small flathead screwdriver. Yours must have been designed to take a special tiny socket. Here's a view inside a typical replacement switch:



Image stolen from AutoZone



As far as a switch sold for R12 vs R134a, I'm willing to bet large sums of your money it's the same component, just adjusted differently at the factory. It's no big deal to adjust an existing R12 switch for use with R134a.

 

What is the vent temperature? That's what is important.

If the compressor is cycling on and off, that means it is pulling the low side down to the point where the switch shuts off the compressor, as designed. I wonder if there may be a problem with your gauge set, perhaps not maintaining a good connection with the R134a adapters installed on the vehicle. I had a similar problem and it took some serious heads-cratching to realize what was happening. Does the low side gauge cycle up and down as the compressor turns off and on? If not, that's a major sign the gauge set is not making a reliable connection.

I had previously suggested the low pressure switch may be way out of whack, but now that I've had my morning coffee and Lucky Charms, I'm leaning more towards the gauge set not making a reliable connection.

Also note, if all else is good, and only the gauge readings are suspect, you should have plenty of nice cool air. Get thee a thermometer to know for sure, instead of just saying it feels cool. Unless your hand was recently calibrated, it's difficult to discern the difference between 38F (good) and 50F (only so-so).

 

I thought I posted this, but don’t see it. On my way in to work today I needed to use the defrost (which works great). When the windshield was clear I pulled the lever over to cold to do my test and POP. I think the connector to the temp switch came off. It was a little hard to move. Now it’s stuck on heat and the lever is limited to motion 1/3 of the cold side. Looks like I’ll come back to the primary issue once I fix this.

any links to fixing the temp lever much appreciated. I’m at work and can do a search after.

grrr

 

https://www.garysgaragemahal.com/hvac-systems.html


Just that from Gary's site. I'm sure one of the experts will chime in soon.

 

Karl take a closer look at the switch adjustment as it may look like it take a flat blade but it is not it is raised.

When I first tried to get my system charged I want to say I also remembered something about the valves not opening or something like that but has been years.
If he dose not have a good gauge set he will need a way to measure the air out of the vents to see if the pump is on / off because of icing of low charge.

If it is the temp, cold / hot, lever this works by cable and maybe it just popped off at 1 end?
I think they said there were 3 different cables for the 80 - 86 trucks but dont hold me to that.
I would see about removing the cable and lube it good before putting it back in place
Dave ----

 

Two distinct possibilities:

1) The picture shows a recessed slot that takes a normal flat screwdriver, like on my truck.

2) The picture shows a raised tab and I am the W word.

As we all know, #1 is the only feasible explanation. The ramifications of option #2 are outside the realm of possibility.

On the ever so slim chance somebody had converted their switch to a raised tab, it would not be too difficult to make a simple tool. Get a piece of solid brass rod or similar, and file/cut a notch in the end.

 

I started a new thread on my blend door control. https://www.ford-trucks.com/forums/1...l#post21579289

The white clip that connects the cable to the box came off. I'm a noob to Broncos - looks like the blend door could be the culprit?? The blend door isn't a smooth move. It's tight in the middle.

Unfortunately, I'll be on travel until Thursday, but I can order parts while I'm gone.

Thanks!!