Diagnosing Evaporator Leaks

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Diagnosing Evaporator Leaks

Postby paulsomlo » Mon Aug 03, 2015 7:58 am

I removed four screws along the front edge of the evaporator box and was able to open up a 1/4" gap between the upper and lower halves. Shining the UV light in, I detected bright green across the fins on both sides of the core. Yet, there is no sign of any dye at the condensate drain. I even inserted a Q tip taped to a wire, deep inside the drain from the engine side, came up dry. No oil residue, no dye. Can I trust the green on the fins as indicative of my leak, or is there something else associated with the condensate that could light up green under the UV? Vehicle is a 2001 Ford Escape, 3.0L V6, location is Colorado, very hot and dry.

Paul
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Re: Diagnosing Evaporator Leaks

Postby Tom Greenleaf » Mon Aug 03, 2015 2:07 pm

That's what the dye is for. You may lack condensate from the altitude + dry air or if it wasn't cold enough to make any since dye was installed? There should still be some oil in drain tube if it ever had produced condensate/water to drip.

Your call always - I would back up the diagnosis with a sniffer with A/C blowing thru it cold or not and it would sing like a song bird about anywhere inside vehicle but loudest + most prevailant out the panel vents. Some (mine) sniffer doesn't like working in any breeze but residual fumes to detect will still be there.

Test twice if you can. Most are a pest of a job so be as sure as possible,

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Re: Diagnosing Evaporator Leaks

Postby paulsomlo » Mon Aug 03, 2015 6:15 pm

Thank you Tom.

Like most DIY, I don't own a sniffer and the UV light is a loaner from Autozone. I guess my concern is that something may have gotten on the fins at the factory, like an adhesive maybe. Or the heater core leaks (although I have no reason to suspect that) and may have sprayed coolant on the evaporator, as there was a coolant leak under the hood that I fixed, and the dried coolant does light up under the UV.

I'm going to go ahead and replace the evaporator; the part is only $80 and I've got the time.

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Re: Diagnosing Evaporator Leaks

Postby Nacho » Tue Aug 04, 2015 12:48 am

It is a major job. The dashboard must come off and then the HVAC module. If you need printed guide, let me know.
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Re: Diagnosing Evaporator Leaks

Postby Tom Greenleaf » Tue Aug 04, 2015 7:08 am

Paul! As Nacho just said it's a major job! If this isn't sure DON'T DO AN EVAP ON IT YET.

I totally doubt anyone will rent a sniffer. That's the most conclusive to me to finish the diagnosis. Dye should (famous last words) expire in time - how long is a guess. Months? Not years though.

Just get a shop with a sniffer to sniff this out for you. Whole interior may set the thing off where there should be nothing. It can get fooled if you just sprayed something inside the vehicle or very strange dirt/oils or something involved in vehicle or lots in area in general.

Did this ever make water when running and working? If so and this is really an evaporator leaking it will have oil evidence dye or not.

Take Nacho up on the offer for procedures for replacing this if you do. No fun and plenty of chances to break things,

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Re: Diagnosing Evaporator Leaks

Postby paulsomlo » Tue Aug 04, 2015 8:12 am

Did this ever make water when running and working? If so and this is really an evaporator leaking it will have oil evidence dye or not.

I don't really know. The vehicle is actually not mine - it belongs to a woman friend and I work on it occasionally. For three years now, I've been filling it with cans of refrigerant each summer, by the next summer, it leaks out. This summer, I decided to do something about it. I put some dye in last summer and the only detection I got was at the seam of the compressor. So this year, I removed the compressor (FS-10), replaced the shaft seal, the large o ring sealing the case halves, and the two o rings that seal the two lines. I also replaced the accumulator/drier, orifice tube, and the o rings at the orifice tube, and all the o rings where the lines connect to the evaporator and the accumulator/drier. I had a shop in Denver evacuate and recharge, ac lasted about four days. Somewhat surprised, when a charge used to make it through a season.

I went ahead and pulled the dashboard today, took roughly four and half hours. Didn't take it out completely, just pulled forward enough to access the evaporator box. Yes, it was a major job, not something I'd want to do on a regular basis. The core arrives Wednesday, as well as new schrader valves, haven't pulled the evaporator box out yet. Is there a good way to seal the system while I've got the evaporator off, or is it a non issue? Also, will I need foam to wrap around the new core? And should I add oil to the new evaporator, if so how much and to which port?

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Re: Diagnosing Evaporator Leaks

Postby Tom Greenleaf » Tue Aug 04, 2015 12:43 pm

OK - Spent a school year in Denver ages ago now. It's dry enough for no condensate. None of the 3 cars I had there had A/C at all. Not sure a 1960 Rambler even offered it? Here was dry early this year and no condensate made here on 2 vehicles till lately, now enough humidity.

Inconclusive for you for evidence to be typical.

So, you have a four day leaker to no A/C which is fast enough to find. Too bad the shop the charged it up properly didn't say something?

Carry on. Try to avoid boosting vehicles that need an annual TWO cans. That's close to the full charge I think. Not good for the system or anything.

Sealing off open ends while working: Just use what works. Foil, plastic and rubber band tie off open ends. PAG oil is water absorbing you want to avoid.

I hope there's plenty of time allowed for this job as some evaps may not fit just right and have you running around for things to seal it up or find a better one than you get?

Whole job is a bit guessy now on oil left in system with this history. Hate to see you be the nice guy and this not work out so well. Do measure all oil OUT of items being replaced. Driers may drill a hole and heat them up so see what you can get out. That much plus a guess of how much. Seems to call for 7 oz. of PAG-46 system total from zero one chart shows just FYI,

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Re: Diagnosing Evaporator Leaks

Postby paulsomlo » Tue Aug 04, 2015 7:28 pm

The shop that charged it put in more dye, didn't do anything beyond that. They had a UV light, but no sniffer.

Yes, I've got time on my side on this one. Although, the woman is driving my other car, which I'd like to get back. At least it has good ac, because she tends to wilt easily. The new evaporator is a "Four Seasons" from Rockauto.

When I had the vehicle up here for the compressor service, I also changed out a leaky radiator and water pump, thermostat, and 10 of the 13 hoses that carry coolant. So, I'm ready to be done with this vehicle. I hope I win this one.

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Re: Diagnosing Evaporator Leaks

Postby Tom Greenleaf » Tue Aug 04, 2015 8:13 pm

I guess I'm just over cautious to NOT blame an evap if any chance it could be something else because they are a pest.

General leak finding: Dye as you see, oil evidence, bubbles even like a tire when spot is possible, plain noise of losing gas not unless a wild leak then the electronic sniffer.

It's become your job so again I just suggest be sure it's exactly that and some are common. This one not known to be common vs some makes totally.

Your call. Getting it sniffed out with some gas in it would nail it so you about can't do this for nothing,

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Re: Diagnosing Evaporator Leaks

Postby paulsomlo » Thu Sep 10, 2015 4:51 am

Nacho wrote:It is a major job.

Yes, it was.

Just wanted to let all of you know how things ended. It's been about three weeks now, AC is still blowing cold. I replaced the evaporator, the two Schrader valves, and the high pressure switch o ring, as well. I'm embarrassed to say how many hours I spent getting that core in and out, but suffice to say, I wouldn't want to do it again.

I want to commend all of you - I'm a member of several other online forums, and newcomers there are not always treated with the courtesy that I experienced here. In spite of it being my 1st post, and being a DIY'er, the tone was civil and not condescending. Great forum, thank you.

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