My '97 standard 4-cyl ranger has 208k miles and last year it finally got low on freon - a local shop added freon with a dye, and confirmed (with a black light) that there were no leaks under the hood. This summer (a year later), it got low again so I had the same shop add freon (1 can), and, again they checked and found no leaks under the hood. I ran the air about 2 weeks ago, that I recall, and it did cool but not at cold as I expected, so I started thinking I needed freon again, but I havent driven it since then, and today, the compressor will NOT COME ON. I assume that is because the freon leaked so much that a low-pressure switch has been tripped and is inhibiting the compressor clutch from engaging (to avoid compressor burnout). Is this right?

If so, can I just add 1 or 2 cans of freon (to the service port on top of the dryer, under the hood near the driver's side firewall)? Since the compressor clutch won't engage yet, can the pressure in the can push enough freon into the line to untrip that safety switch and allow the compressor clutch to engage? If so, then, I assume I would be adding freon while the engine is running and the a/c dash switch is turned "ON". Is this right?

If this works, and the compressor comes on and cools the cab (for a while, anyway), then, can I assume that the evaporator coil is leaking, since their blacklight shows NO LEAK under the hood anywhere? Is there a way to CONFIRM positively that the evaporator is leaking freon?

I am hearing that replacing the evaporator coil is a nightmare (labor-wise), so, I want to be absolutely sure that the current evaporator coil truly is leaking before i take that step.

I sure hope someone on this forum has had experience in this area.

 

Hey Jerry....I have a 98 ranger 3.0 with 180k miles on it. My ac has a slow leak in it and repair shops really rake you over the coals money wise to add freon. I finally bought an ac refill kit sold at autoparts store. Simple to use and I have had good results for my slow leak problem. That said I have to add that in my vehicle the compressor would cycle (click on and off) a lot when freon gets low. That constant cycling has always been a warning to me to add freon. In your case you are not hearing any clicking or cycling from compressor, right? So, as a complete novice when it comes to auto repair, I would buy ac kit (freon with screw on pressure gauge and trigger) and at least see what built in gauge says about your pressure. Even if this kit does not help with ac problem you will probably be able to use it sometime in the future on your ranger or any other car

 

You definately have a leak. Before you start throwing money into parts, I would look with a fine tooth comb for the leak. Are you positive that the shop added dye to the system? I've repaired 7 systems that a shop charged for adding detection dye to the system. The vehicles came to me with NO DYE in the system. The shop was trying to squeeze the customers for the $$$ of replacing a compressor which they never would have replaced anyways. That shop is no longer in business. One was a minute rub hole in a line and the rest were breached O-Rings. I would suspect a breached O-Ring. Look around all connections. Even the bolt-together connectionsa as these also use O-Rings. Also look for any chaffing on lines and look around the lower part of the compressor by the clutch. The shaft seal may be leaking. If it's a slow enough leak, dye may not appear or may be so minute it's almost undetectable. A totaly dark garage is great for finding these hidden rascals. And remember, If you open the system up, you should replace the accumulator. Which pops up another thing to look for. If your accumulator has a cover/shield over it, check for rust thru on the accumulator.