Not working A/C

[jarek_rugby]

i have problem with A/C.
There is no power. I checked on wires. Cluch is working (when i put wires directly from acu).
Where is AC relay in 1986 EFI 5.0 F-150?
I could not find it.

[Gary Lewis]

Jarek - I'll bet that your system leaked some of the "freon" over the winter and the pressure is below the cutoff of the Clutch Cycling Pressure Switch, shown circled below.  You can find the schematics here: Electrical/EVTM's/1986 EVTM/AC & Heater.

And note that in the upper left corner of Page 143 there's a description of how that switch works.  But it isn't unusual at all for these systems to leak a bit over the winter and the pressure be below the cutoff point of the switch.  However, add some refrigerant and it'll probably work.

[PetesPonies]

Remove the plug from the cycling switch. Jump the terminals. If the compressor comes on, you either have a bad switch, or as Gary said, not enough freon.

[jarek_rugby]

I will check, but next question is :
what kind of liquid should be in?  r134 or freon?

[Gary Lewis]

The truck came with Freon/R12.  But since you can no longer buy that surely it has been converted to R134a.  Does it have a fitting like the ones below, or any of those shown here: https://nostalgicac.com/fittings-hose-kits/r12-r134a-adapter-charging-port-fittings.html?  Those are conversion fittings and that would indicate it has R134a.

[jarek_rugby]

No, it has only for freon.
I read that r134 is based on synthetic oils but freon on mineral and in future r134 could damage seals and compressor.
I read on my import papers that in Germany they suck r12 from my bullnose :(

[Gary Lewis]

So they didn't put anything back, just removed the R12?  If that's the case then you almost for sure need to get with an A/C company and have them pull a vacuum and fill it with R134a.

Most, if not all, of these trucks are now running R134a, without problems.  You really don't have much choice.

[jarek_rugby]

OK, thx.

[85lebaront2]

You will need to get a new R134a compatible accumulator (large can on underhood A/C casing) possibly a new orifice tube and new oil to replace the mineral oil in the compressor and rest of the system. Be sure you get the correct oil for the conversion, the normal R134a oil will not mix with the mineral oil and can make a huge mess of the system.

Properly done, it will cool very well, I ran my crew cab with a converted system for a number of years and it cooled quite well unless it sat and heat soaked after stopping, then it took a bit to get cold again, but it did that before being converted so it was more of a design issue than a conversion issue.

[jarek_rugby]

I jumped it and compressor comes on :) But now i have to check pressure

[Gary Lewis]

If they sucked all the refrigerant out then that explains why it wouldn't come on.  And, if so, you'll have no pressure to speak of.