I had my R12 AC fluid changed to R134 and the AC worked good. The next time I started it the engine started up with a rough idle. I ran it 4 more times and it got worse and I think the AC quit cooling. Anyway, it looks like there is a new vacuum plug on it. I can't find and similar under hood pictures. I moved from CA, which is smog heavy to Az which isn't and I think the AC tech did something. Of course he quit working on cars since then.

 

I guess the moral of the story is that everyone should take pictures of their engines so we can go back and look if necessary.

You should provide a few more details.
Year of vehicle and mileage often helps.
Besides "AC fluid" (refrigerant and 'PAG' oil?) I thought a conversion to 134 required an orifice change.
Had the AC been working or has the compressor been left idle?

 

Thanks for the reply. The year is 1991. Its a 4.0. The freon charge valves were changed out, the system evacuated & recharged.
I have some older pictures but they aren't detailed enough. If anyone has a similar Ranger I'd sure like to see their pictures. I've done a web search and nothing comes close.

 

In the 2nd picture, that black plastic cylinder on the top of heater box is the Vacuum Reservoir
The "T" in the foreground is the Check Valve for the Vacuum Reservoir
One of the connected lines should run to the reservoir, the other should run to the engine's upper intake manifold, drivers side, to the "vacuum" manifold, has a few vacuum hoses attached there, like power brake booster and PCV Valve

The capped port on the "T" was connected to a vacuum line that ran into the cab, it controlled the "fresh air vent valve" inside the cab
It goes into the cab between heater box and passenger side inner fender so comes out in the cab under glove box but all the way over by passenger side kick panel
Picture here inside cab: https://www.therangerstation.com/for...lug-jpg.51618/
This is not a 1991, lol
But it shows were the vacuum line comes into the cab, the white and black lines/hoses, yours would only have the one line but could have two connections
So look in the engine bay for that black line over by the heater box and inner fender

But.................nothing in this system would cause no AC or rough running engine, especially if vacuum port is capped off

 

Thanks you for that. It ran great before he worked on it.Its got about 125k miles on it and had a tuneup before I drove it here from Ca.
The rough idle came on slowly after he worked on it. Every time I drove it it got worse. I seldom drive it but I'm not driving it anywhere until I track this down.
I'm thinking that it is a vacuum line that has too big of a plug on it or got jostled when he did his work and if the AC is not doing good is still has a leak.
If it does then the compressor will just not kick in. I have to fix the rough idle before getting into that.

 

4.0l OHV engines abuse spark plugs, lol
Rough running could be spark plug issue, especially if its at idle and engine is smoother when driving

Motorcraft or Autolite seem to last the longest, NGK are OK if first two choices are not available
I would pull spark plugs an have a look at the tips, clean and regap, 0.054 is spec

Also dump a can of Seafoam or similar injector cleaner in the gas tank
From the description you could have got some "bad gas" which can cause issues with fuel injectors and the spark plugs both, and this gets steadily worse even after the "bad gas" is gone


If you didn't notice it right after you picked it up then my guess is its not related to the AC work
AC system has no connection to anything in or on the engine, including wiring

 

Give the MAF sensor a clean? It's frequently mentioned when rough idling comes up. Or is that only the 4.0 SOHC?

 

Does anyone have a picture of the vacuum line to the fresh air door that RF Veteran referenced ?
I hear the noise in the cab on the passenger side but under the hood I can't see where it is.
There is also a pigtail tied to the vacuum line to the manifold there that I don't recognize.

 

The cylinder in the pictures is the Vacuum Reservoir, just sits on top of heater/AC Box but not used by AC

Usually only found in that location on 1994 and earlier Rangers that used Sliders and CABLES on the heat/AC control panel, looks like this: http://img.justparts.com/eImage/0471...80811488ba.JPG

So cab vents or heat system was done by cable if your control panel looks like that, it was all done by cables
BUT(big but) vacuum was used inside the cab to open and closed the fresh air vent, usually only in MAX AC setting, that would send vacuum to the door under globe box which would shut off fresh air and allow fan to pull in Cab air only

So look under glove box for a WHITE vacuum hose, that goes to the vacuum motor that opens and closes the fresh air vent