General A/C troubleshooting advice

[mark_gober]

I've got a general a/c question. It's not necessarily windstar specific, but it would help me in fixing my 1995.

I was told that my 1995 Windstar had a leaking evaporator. I know that this certainly can happen, but I'm also a touch distrustful of mechanics. I am suspicious that they are telling me that and the real issue is that the o ring somewhere is bad. So here's my question.

How can I track down where an a/c system is leaking?

I have two windstars....both have small leaks in the a/c system. The 2000 clearly is leaking from the suction hose. I put the UV die in the system and it is clearly visible on that hose. (even without the glasses).

My 1995 has had a shot of that stuff and I cannot find any evidence of it anywhere. I also have a Snap-on electronic freon detector that my father gave me. It does appear to function, but quite frankly, it just goes off randomly. I can have it the breeze and it wants to chirp, so I'm a little distrustful.

I like hard/fast troubleshooting methods. I'd prefer to section the system off and pull vaccuums on individuals sections to find out where the leak is. Has anyone ever tried this, and if so, how do you seal each section's end?

I don't mind spending money on car parts, but I HATE buying something only to learn that it didn't fix the problem. I look forward to any shadetree/pro troubleshooting techniques anyone has.

Mark

[wiswind]

One thing that is importand.....that you bring up......if you need to add refrigerant to your A/C system......it went someplace.......and you have a leak.
When I went to my trusted family owned repair shop and told them that I needed to make an appointment because my A/C was cycling on and off......so I figured that they would find it low in refrigerant.....and that if that was the case......I figured that they would need to find the leak.
They told me right off that they were surprised to have a customer come in and tell them that they thought that they had a leak because it was low.
They said that usually folks come in and tell them that they need it charged up.....and they think that they are getting ripped of when they are told that they are low because they have a leak.

You can also do more harm than good with the leak sealing stuff that places sell with the "recharge" kits.
In Wisconsin.....the average person cannot go into a auto parts store and buy any type of refrigerant for a vehicle......only licensed shops can get it.

In my case,.....they put some R-134 in, used the "sniffer, hoping that it was something simple, like a "O" ring, could not find a leak, put the dye in.....and sent me on my way telling me to come back in a month or so (it was the end of winter, not much A/C use then).
Within a couple of days......it was cycling again......so I unplugged the compressor to prevent it from cycling when I ran the defroster.......and went back to the shop.
They found the dye coming out of the water drain from the heater box.......so we scheduled a appointment for them to have it a full day to replace the evaporator......and they removed the remaining R-134 from the system.....and gave me a credit for what they removed.......and I came back for the repair.

The key to having ANY work done on your vehicle is having someone that you can TRUST to be both competent and honest.

For the DIY person......when someone posts a problem.....I try to have them check out the cheap and easy solution......and routine maintenance items.......then move on to looking into the other things.
Like you said......no one likes spending money replacing expensive parts that are good......and a lot of shops do that (when they lack either of the 2 things that I mention above).
It hurts even more when it is some obvious thing that one should have done as routine mainenance....and put it off to save money.
Too many people drive their vehicles......and don't do anything more than gas and oil until something goes wrong.

[tomj76]

I found my leak in the high pressure liquid line with dye. It took a while (3 months) before I noticed the dye leaking out. I bought a UV incadescent light bulb for $3 to find it, but by the time I noticed it the dye was visible without the UV light.

As Wiswind eluded, the evaporator is very hard (if not impossible) to see without removing it. Due to this fact, I'd be asking the mechanic how they decided the leak is in evaporator.

It's interesting that R-134A is the main ingredient in some "canned air" products, yet when R-134A used as a refrigerant it's illegal to intentionally vent it.

For example:
http://www.specialized.net/Specializ...-Can-3545.aspx