I added A/C to my 95 f250 everything is brand new though including hose's and the pump.

Okay i can buy a 30lb tank of freon for almost as much as a single charge of my truck. Where i work we have a vacuum pump along with the gauges all for 134A. (of course no one knows how to use it anymore.....)

I know i need 33 ounces of freon so 2.1+- pounds and 7 ounces of oil.

How do i go along starting this. I know where to hook up the hose's but don't know how to really read the gauges. I know with a new system ussaly about 2 hours of pumping/vacuum is required. But i don't know how to read the system not to overfill it. I want to learn how to do this. I am adding A/C to a 92 f150 along with having to fix about 2-3 tractors that the A/C has never worked. I realize it may be cheaper if i had one truck to fix. But in this case i have 3-4 to fix.

Even if someone has a Youtube video they can show me, or anther fourm that would be great!

 

Been so long I really couldn't tell you anymore. I remember you have to hook into high and low side. If you're using a 30lb tank make sure you lay it on it's side so you get both the gas and liquid combo. Make sure you add your oil first, unless you have the 134A with compressor oil added into it already. Here's a link to some more reading that may help.
Denlors Auto Blog » Blog Archive » Adding Freon to Car AC – Gauge Readings Explained

 

You will have to use a scale with your cylinder on it to tell when you have put in the right amount. BTW, R12 is called 'Freon'. The equivalent name for R134a is 'Suva' but nobody uses that. However, if you say 'Freon' you are assumed to be talking about R12.

7 ounces sound like a lot of oil. Your new compressor should have 4-5 ounces in it already. If it doesn't (meaning it came 'dry') you need to put the oil in the compressor before you evacuate and charge. You cannot put all the oil the system requires thru the hoses or else your compressor is going to be running with no oil for quite a while.

 

Thanks i ended up finding a awesome YouTube video for this, and when i find it again ill post for future reference's.


I do have a question about the switch's - I added the A/C to this truck Everything is new but i had the wiring harness's already on the truck just where dead ends.

95 f250 5.8l does it have a high pressure, low pressure and a cycling switch.
I can find where the High pressure goes and the cycling switch.
But cannot find a spot for a Low pressure, any idea's if it even has a separate switch that is.

 

The low pressure and clutch cycling switch are one and the same. It provides both functions.

Cut from my Ford Service Manual:

The A/C cycling switch is located on the side of the suction accumulator and controls cycling of A/C clutch. When the pressure increases to approximately 276-324 kPa (40-47 psi), the A/C cycling switch closes. When the pressure drops below approximately 163-175 kPa kPa (23.5-25.5 psi), the A/C cycling switch opens to stop compressor operation. In ambient temperatures below approximately -1°C (30°F), the A/C cycling switch will not allow compressor operation because the switch will open due to low system pressures.

 

I pulled a vacuum for about 1-1.5 hours. Filled it with right around start weight was 35.8lbs, It would only pull to 34.01 lbs (1.8lbs. requires around 2-2.1) of R134. And the pump still wont come on. If i run power to the pump it runs good and plows cold air. I know i have oil in the pump and i know i have R134 -
Since i added the A/C on this truck I'm wondering where to start as far as checking if everything is getting power. Everything is for a 1995 F250 - the only part that came from the 91 doner cab was the blower motor wiring harness and the Controls in the cab. Otherwise the wires for the compressor and High pressure shut off where already installed.

Anyone with idea's would be helpful!. I did try jumping the Low pressure switch didn't seem to do anything, but i may not have had a good jump connection. I really think I'm not just sending power though the sensors, and to the pump even when i have a good charge.

On a side note i ended up recovering the freon and pulling another vacuum - It held all night - So im assuming i do have a sealed system. Also Literally everything on the A/C is new. Aside from the wires. And im using a scale to measure the Refrigerant. it is a hanging scale but seems to be very accurate.

 

You'll probably need a wiring Schematic but it's probably the WOT relay in the fuse block or it could be the diode for the AC blew out. If you're jumping the power over and the AC is working, it's got to be a relay, bad diode or a bad wire.

 

A schematic would be awesome (ill start googleing for one), because i'm wondering if due to me adding this whole system if im just missing somthing like a relay. And of course i realize i could just be missing a wire or have a bad one.

Where is the WOT relay even located?????? Ive googled this and not really found a answer for a 95 f250 w/5.8

 

I know on my 91 Bronco, when I rebuilt the A/C, the compressor would not come on. I checked for power at the low pressure switch and had none, so I pulled the a/c panel out of the dash. The fan was working, but I found the a/c compressor clutch had it's own power coming in separate from the fan. I found a 2-wire connector unplugged behind the dash and that was the 12V going to the a/c control panel for the compressor signal.

 

Ill check that for sure, thank you. I'm figuring that if im not getting power at the low pressure switch im going to follow the wire into the Climate control **** (or w/e you call it) and see if i jump power to it there if it kicks everything on. I really have a feeling i'm just missing power like you said above.

Really wish i could find a wiring schematic, then i could see if i'm just outright missing a wire. Trying to find 4 wires off the A/C pump and high pressure switch coming through the firewall and tracing them does not seem overly easy....

 

On another subject of the same matter: you did replace all the rubber o-rings (black) with HNBR o-rings (green), right? It won't affect the problem you're having, but it should be done.

 

(A/C Generally) see image below.....................

 

Thank you guys for all the help!!! Since everything was new it already had the green o-rings.

I got the A/C to turn on got it to cool down to 50 degree's. Then after maybe 10 min it was blowing 60. Basically i know the A/C compressor is turning on and working, i did not lose any vacuum over a 24 hour period.

Ill pay someone at this point to fill it. I will use my R134 Can on the tractors i have to refill and do a lot more research on how to fill a system but it all works so thanks again guys!

 

What did you find was causing the compressor to not engage before?

 

Low pressure switch.....even when I tryed to jump it I was not making a good connection so I made my own little jumper and it worked. So mostly just lack of experience with a/c also to get the gas to go into the truck I had to turn it upside down or it would not pull the r134 from the tank.