AC blows cold when truck moving, warm when idle

[TrexMex]

Well, I hust had a whole page typed out here and lost the whole fing thing because the page somehow reloaded and cleared my whole box out :

Your '94 had eirther R-12 or R-134a depending on it's production date. If you find any black goo in there (Black Death),you'll need to change at minimum: compressor, condenser and orifice tube. Make sure all the lines and hoses are thoroughly flushed out as well (if the evaporater doesn't come clean in one flush, I suggest replacing that as well. Any debris in the system will quickly cause the new compressor to fail as well.

Yeah I see the R134a Sticker in the accumulator, so I guess that makes things easier. I'm ordering the parts and will see if I get the vac pump and flush kit by this weekend, if not guess I'll have to wait for the next one.. I think what I can start doing is to tear the thing apart and start looking for the black goo. I'm pretty sure the compressor is toast but then if I don't see the infamous "black death" I would only be replacing that component?

 

[TrexMex]

Well I finally got to overhaul my whole ac system...

Bought a new compressor, condenser, accumulator and orifice tube and replaced the hose assembly with a junkyard one...

I pulled the whole evaporator/blower assembly out of the truck for cleaning and while I was at it I removed what after 15 years was left of the casing fiber glass insulation. I replaced it with insulation tape and foil tape and that worked really good in keeping the engine bay heat where it belongs. I also used insulation tape to seal off the evaporator inlet/oulet lines to avoid any cold air flow (i.e. flow I would be losing out of the vents).

The old (blue) orifice tube had certainly seen better days, it was filled with all kinds of debris, I replaced it with the same type since I didn't want to pay the extra cash for the severe weather, variable orifice tube; 30 bucks vs 3 dlls?? kind of a difference there.

Definetly the most cumbersome part was taking the old condenser out. Since the PO welded a front hitch to the chassis, the radiator and condenser can't be accessed from beneath the truck so I had to remove the front grille and the radiator (which for I had an auto explorer replacement sitting around waiting for an excuse to be put in) in order to get to it. I went ahead and replaced all the weatherstripping in there since the old one turned into dust just by merely looking at it (dang 105+ F Summers).

After putting in the new components I went ahead and flushed the evaporator and the junk yard hose. Junkie, regarding the high pressure hose "muffler", as it turns out its called a "mixing box". I use them all the time here at work when we set up performance tests where a static pressure measurement is needed. It basically stabilizes flutter caused by the compressor in order to have an accurate static pressure reading for the high pressure sensor. Kind of a damper (or muffler ). It's amazing how you have something right in front of your nose and sometimes forget automotive applications work under the same engineering principles.... Anyways the thing should be hollow, with some passages (to keep pressure drop to a minimum) so it can be effectively flushed.

Everything was flushed effectively and I proceded to install al the components and adding PAG46 oil to it. I read on an applications chart the ranger uses 7oz of oil and 22oz of R134a in pure R134a systems, so I added 2oz of oil to the compressor, 1.5oz to the evaporator, 1.5oz to the condenser and the rest to the accumulator once I opened for plugging it. After everything was installed I hooked up the vacuum pump for 10 mins, checked for leaks (left it overnight) and yesterday morning ran the pump for about an hour. I proceeded to fill out the system with refrigerant and voila!! cab is cool again!! I got ~40F out of the vents when cruising and ~55-60 when Idling at ~45-48 psi on the low pressure side and ~250-260psi on the high pressure side with an ambient temp of around 100-110 at noon. When the ac is off pressure is around 110psi in both gauges..

Through the whole process I replaced all the old o-rings with new ones and lubed them before installing them.

Thanks to everyone that have posted on this thread giving advice and opinion, this was a learning experience and more important a safe and successful learning experience from beggining to end...

.....Now to wait and see what will fail next in my very own "can of worms"

 

[4x4junkie]

Cool deal! (pun intended lol)

Sounds like you got it all together and working again.
Thanks for that on the "muffler", I figured it wasn't something that was overly critical for the A/C's operation.