Evaporator Leaking

It seems that my evaporator is leaking. It leaks when the AC compressor cycles off when the AC/defroster is on. It's odd to me that it only leaks at that moment, but it's consistent.

Does anyone know if I actually have to remove the dash to get the evaporator assembly out? The CD says to remove the dash and the support that's in there. The diagram shows that removing the glove box and glove box support might be enough for that part however.

Who's dug into the dash that far? I'm sure that paying someone to do that would cost me an arm and a leg.


Maybe I'll just sell the VX to a stoner, considering that with the air on recirculate and the defroster on, you get a nice blast of r134a every minute or two.

The IMG is next, but after it warms up that quiets down. I'll just replace those when I change the timing belt. Is the 1999 interval 60k or 90k?

-Tad

I removed the glovebox and some other pieces of trim when I fixed my leaky firewall last summer (took 5 minutes). I worked in, around, and up behind parts of the air conditioner and if I recall correctly there should be plenty of room for you to work (or at the very least get a much better look at whats going on). I'd also reccomend taking out the front seat on that side so you can get yourself right up under that dash. Just my .02

Building airconditioning in your car is actually quite easy:

http://www.vehicross.info/gallery/da.../1068airco.jpg

;Dy; ;Dy; ;Dy; ;Dy; ;Dy; ;Dy; ;Dy; ;Dy; ;Dy; ;Dy; ;Dy;

So it's really leaking refrigerant? Or you see mist out of the vents and are assuming it's refrigerant?

Nate

Yes, it is leaking refrigerant. I can't see it, but I can smell it, and so can any passengers who ride with me.

-Tad

So, would you describe the odor as "slightly sweet?"

Or pungent? (only if you smoke or have open flame around r-134a).

Or, is it musty, like mildew?

Nate

It smells like I'm using a can'd air duster. It doesn't smell like antifreeze or mildew. The interesting part is that it is intermittent. Under normal AC operation the compressor switches on and off. It's during one of those changes (when you normally hear the small hiss) that the smell appears, and it only lasts long enough for one breath. It took my a while to get my wife to smell it. I'm going to check the pressure in the AC system shortly and see if it is lower (as I expect it to be).

-Tad

Well, sounds like it might indeed be refrigerant.

Unfortunately, I have not found a car yet that allows you to remove the evaporator without cracking open the A/C system.

Leaks near the Thermostatic Expansion Valve (TXV) are rare, unless the vehicle is known for it. It's not that I doubt your diagnosis, simply that verifying the problem by removing the evaporator is painful if you are wrong, and painful if you are right, so I'm trying to see if there is a way to confirm this without removal of the evaporator.

Here's what I would do next:

First, check the sight glass while the system is running. If you see bubbles persisting while the compressor is on, then you are low on refrigerant.

I would add some dye to the system. You can buy cans of dye (with a small refrigerant charge) and add it the LOW SIDE of the system. If the low connection is at the compressor, care must be taken to avoid slugging the compressor; use a bowl of boiling hot water to dunk the can into in order to help push it in as a gas. (Use the can right side up for gas, upside down for liquid). It's probably safe to tip the can upside down for just an instant at first (while the compressor is running) to shoot just a little liquid into the system. Then, let the hot water heat and push out the rest as gas. The goal is to get dye into the system; refrigerant is just there as a propellant.

Letting the system completely decompress out of refrigerant is a bad idea unless you are prepared to replace the receiver/dryer, evacuate the system completely, and refill it with new refrigerant. The dessicant in the receiver dryer absorbs moisture and when it's exposed to air, it gets used up, and the small amount of moisture in the air causes corrosion inside the system.

I'm not saying don't service your own A/C; I recommend a new R/D, full evacuation (appropriate vacuum pump for 30 minutes) and a full recharge shortly thereafter.

Adding the dye to the system will allow you to diagnose a potential leak under the dash without taking it apart. The dye will make its way to the leak, and will eventually start to wash out the drain tube with the condensation. Even if it doesn't get this far, you should be able to see something with a small mirror on a stick and a flashlight with the glovebox removed.

If you dead set on removing the evaporator, you should drain the system at the lowside service valve (after the system has cooled so that it is ambient on both sides!) You may need a special valve adapter for the new style valves. Stand back, if the stuff comes out as a liquid, you can suffer severe frostbite on the skin or eyes. Also, whatever it blows onto may be damaged by the extreme cold (paint?). After it stops hissing, find the low and high side connectors where they enter the firewall. Disconnect them. They will likely pull through into the cabin.

Have at the evaporator from the inside. The evaporator may slide out, may be in an enclosure that is held in with screws or bolts, but it should come out of there without a full dashectomy.

Nate

^ that right there, is impressive folks.

Yea, if I have to do that, I'm going to do it right. The shop will be replacing the dryer and evac'ing the system before refilling it for me. I *can* top off a system that's low, but this vehicle is a bit too nice for that kind of treatment. I want the right amount in there when all is said and done.

There is also a seal conditioner which would fix my leak assuming that the leak is between the evaporator and the expansion valve (they are both inside of a plastic housing under the dash). I'm doing some research to see if there are any harmful side effects to those.

-Tad

Nate,

Could you use a refridgerant detector at the vents to confirm the leak was in the evaporator as opposed to in the engine bay? or at the condensate drainpan outlet assuming the refridgerant would collect at the lowest point?


Pete

Yes, but the electronic detectors (mine's a Snap-On!) are notorious for false alarms.

The problem is that the detectors detect all kinds of chemical compounds that are NOT R-12 or R-134a. I can make mine go off by burying it's nose in the carpet; I think it's the vinyl chloride (new car smell) that causes it to beep.

Dye is almost foolproof. The only thing that can trip you up is if the valve where you added the dye is leaking. Clean off the valve after you add the dye; it it comes back, you have a leaking valve.

Nate

Tad, I forgot to mention, the dye for A/C systems is really just compressor oil with dye in it, so adding dye is actually beneficial.

If you are low on compressor oil, then the addition of dye (oil) may restore the health of a bad seal.

I have often wondered why there is no dye in the system from the factory; coolant and ATF get dye, so why not A/C systems? It would have made my life a lot easier in the shop...

The sealants are not a good idea. They tend to be hard on compressors and can gum up an Expansion Valve.

FYI, to all, run your A/C once per month (year round) and you will likely never experience an A/C leak. This keeps the oil circulated and keeps the seals coated, helping prevent deterioration of the seals and a leak of refrigerant.

Good luck, keep us posted.

Nate

Does anyone know if the evaporator from a 1st gen Rodeo is the same as in the VX? They look like twins in the VX manual photos.

-Tad

Quote:

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Originally posted by Nazrat
Does anyone know if the evaporator from a 1st gen Rodeo is the same as in the VX? They look like twins in the VX manual photos.

-Tad

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Nope. It is exactly the same, except for the thread on the intake fittings. Ask me how I found that out :(

I'm done, off to the shop with it.

-Tad

Anyone have a photo of the "expansion valve" in a 1999. Took my "new to me" to the shop yesterday to have it recharged and some dye added to find the leak. The A/C cooled while on my test drive Friday but would not work at all Saturday and Monday. Taking it back to the shop Friday for a new radiator (pin hole leak at the top) and hopefully a fix of the A/C. South Florida is no fun without airconditioning, even in December.

Rod