replacing the evaporator core

[bigbaby1234]

How difficult is it to replace the evaporator core and location of it. The compressor comes on my mechanic did dye testing on system and with his black testing light he saw no leaks so he determine it was the evaporator.thanks guys again. I want you all to know that helped me on the suspension problems thank you that fixed the problem and saved me tons of money. Believe me this old vet needs all he can save thanks again

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[Cadillac Jim]

The 1997 FSM, page 1B-24-25, says that you need to disassemble a large part of the dashboard and drop the engine cradle to get the blower motor and HVAC Module assembly out of the firewall into the engine compartment. This is a humongous job. 47 steps are listed in the FSM.

The evaporator practically never leaks in these cars. Much more common places for the A/C to leak are the condenser (by far the most common, see below) compressor seals, pinholes in the hoses, imperfections in the crimps where the fittings on the ends of the hoses connect, and the O-rings where anything connects to anything else.

A very common problem is a leak in the condenser. This is because people often forget about the tar-paper air dam under the radiator, which serves several purposes. The important one here is that it keeps road debris from hitting the condenser, power steering cooler, and radiator. These leaks can be hard to detect because the radiator fans pull leaked Freon through the radiator when the A/C is on and dilutes it in the radiator air. If your car needs a can of Freon every so many months, regular as clockwork, year 'round, this is probably your problem. If your air dam is missing and has been for months or years and you put any highway miles on your car at all, this is likely a problem whether or not there is another leak.

The second most common problem is compressor seals. These can be hard to detect because Freon may not leak except under certain conditions, such as a hot car idling with the compressor clutch cycling, and flow of underhood air takes away the Freon quickly. A compressor that looks clean in the shop can lose your Freon in a few days this way.

All your mechanic has done is establish where the leak is *not*. He hasn't established where the leak *is*. The FSM, page 1B-19, recommends the use of a sniffer. The Goodwrench Special Tool sniffer, J39400, operates from the cigarette lighter and has a probe that will find R-134a leaks wherever they are in the car. They are sensitive enough to find traces of Freon in the air from the evaporator while the car is off, and remnants of Freon from intermittent leaks on the compressor seals. The 1997 FSM is 14 years old and there will likely be better ways now, so I would rent a sniffer from an auto parts store and find the leak before I committed to a repair. Don't take the UV dye results too literally because the sniffers are far more sensitive.

One last thing: if you do this job yourself, you may run into Federal laws regarding Freon. Licensed people pump the Freon out of the car and store it, and put it back when they are done. No one else can legally buy Freon, with arcane exceptions. You may want to consider letting a good A/C shop or a chain with a good reputation for A/C work do this for you - and guarantee their work.

[Göran W]

I had mine done a few days ago. Second time in six month.... This time whit a "sniffer"! It was th compressor seals. Cant be detected but from under the car and plastic covers removed. Will hopefully be good for a few years now!

[joeb]

great points jim. huge work to change evap so i would pay some shop to really find leak before doing this work. my system never leaked till i changed compressor. i would bet it is the compressor leaking now.

[Cadillac Jim]

Attaching compressor and other fittings with just the right type and amount of lubrication of the O-ring for each joint is an art, too. Your problem might be a 25-cent scratched or kinked O-ring.

[joeb]

i put on new compressor sealing washers last summer in an attempt to fix leak. no difference. i would love working a/c. adding freon makes cold air. for a day or 2. i changed the firewall thermistor 2yrs ago. maybe that sensor is leaking? i added uv dye and can see no leaks.

[Cadillac Jim]

I would not any more dye or other non-Freon in my cooling system. The Cadillac system for my car holds (1997 FSM page 1B-25) only 2 pounds (0.91 kg) of Freon R-134a and 9.6 fl. oz. (285 ml) of oil total. There is no room for other stuff. If you add too much dye you may end up having to pump it down, recover the Freon, possibly drain the oil from the accumulator, compressor, evaporator - and condenser! - and start over.

And, dye has proven not to find your leak. The sniffer is the answer.

[bigbaby1234]

Thanks guys, and to you Jim for the explanation of a life time. I am going to a A/C tomorrow and get this fix. I honest believe my mechanic is very afraid of this car eveytime I take it to him now he hesitates, and then he thinks and then he says well I thionk you made need this or that and he reccomends me down the road, so Jim I guess I will be going down the road from now on. Thanks a million guys and God Bless the Caddy nation.

[rockfangd]

A very common problem is a leak in the condenser. This is because people often forget about the tar-paper air dam under the radiator, which serves several purposes. The important one here is that it keeps road debris from hitting the condenser, power steering cooler, and radiator. These leaks can be hard to detect because the radiator fans pull leaked Freon through the radiator when the A/C is on and dilutes it in the radiator air. If your car needs a can of Freon every so many months, regular as clockwork, year 'round, this is probably your problem. If your air dam is missing and has been for months or years and you put any highway miles on your car at all, this is likely a problem whether or not there is another leak.

While you mention the air dam. It is very unfortunate that it is discontinued.

My 96 Deville is missing half of the air dam. and I tried to find a used one, it proved impossible. Most peole dont think anything of he air dam, but it has many uses, It helps the cooling system cool more efficiently, and warm in the winter. It keeps debris out of the radiator support area. It keeps debris out of the washer pump area also, and even the electrical panel lower side.

My point being is something so unnoticed can save you lots when taken care of

[joeb]

i had my condenser out when i did the motor 4yrs ago. did not change the o-rings on fitting block near abs unit. looks like i touched more seals than i thought.

[Cadillac Jim]

You don't need anything you can't get from the hardware store for an air dam. A length of heavy-duty tar paper as used in roofing, some plastic push-in fasteners avaialble in the hardware aisle aloing with the brass screws and household and automotive fasteners, a pair of snips capable of cutting the tar paper, and a ream are all you need. If you don't have at least half of the old air dam to work with, you might want to get a length of butcher's paper to push up against the bottom of the car and mark the pattern and the fastener holes, then tape it to the tar paper as a template. You can do the whole thing in a couple of hours, including the trip to the hardware store.

GM has to manufacture, test, package, ship and store these to offer them through the dealer. I would expect that dealers just make them up themselves anymore.

[KHE]

How difficult is it to replace the evaporator core and location of it. The compressor comes on my mechanic did dye testing on system and with his black testing light he saw no leaks so he determine it was the evaporator.thanks guys again. I want you all to know that helped me on the suspension problems thank you that fixed the problem and saved me tons of money. Believe me this old vet needs all he can save thanks again

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No way I'd replace an evaporator with a diagnosis like: I couldn't find the leak so it must be the evaporator......

The compressor in that vintage was known for case seal leakage. If the evaporator was leaking, a simple test with an electronic leak detector's probe down the center outlet would tell the story.

[bigbaby1234]

Thanks guys again and speciaaly to jim yep the compressor and the condense was bad so again this site is nthe truth and nothing but the truth thanks for saving me thousand bucks plus labor

[rockfangd]

very good. I say find another mechanic lol