AC evaporator flush recommended? (1 Viewer)

[zx9r]

Any opinions?

I had a leak in my '94 AC system (condenser and o-ring at receiver/dryer) last summer. While in the process of replacing my radiator, decided to take care of the condenser at same time.

Have the new condenser installed now and about to take to shop to have system evacuated and recharged. But beginning to consider whether or not I want to flush the evaporator while the system is open. I'm leaning towards leaving well enough alone but would hate to miss this opportunity if others have good experience doing so or bad experiences because they didn't...

On one hand worry could cause new leak or dislodge crud that will make it's way to the compressor some day but also worry that I have too much old oil in the system (at least lots of green dye from trying to uncover the leaks).

Anyone try one of those DIY flush kits?

 

[1972FJ55]

Unless your system has debris in it from the compressor coming apart, or if the system has been open for an extended period, skip the flush. The evaporator doesn't hold much oil, so I wouldn't worry about flushing it just to remove oil.
Good luck,
Rex

 

[zx9r]

Thanks for the comment.

I have no evidence of debris. But I haven't really done a close inspection. Where do I find the expansion valve or TXV? From what I've read this might be the best indicator of how contaminated the system is.

Has been open for a couple months but fortunately drier winter months so maybe that helps...

 

[1972FJ55]

The expansion block is attached to the evaporator core. You have to remove the evaporator housing from under the passenger side dash to change it. When you changed the condenser, did you drain any oil out of it and if so, how did it look? If if was black or has particles in it, then I'd proceed with the flush. If it was clear, I'd skip the flush. As far as being open, I'd put a drier on it and call it good. If you haven't already, put a couple ounces of PAG46 oil in the condenser and another oz in the drier. The green dye is usually put in a 1/4 oz shot, so although it looks like a lot, it's really not, unless someone got carried away.

 

[Monty231]

I have a leak in my system as well and I am planning to do a system flush. I have done them in the past using mineral spirits and compressed air and both vehicles are still cooling fine today. Also, while you have it apart you may want to look into replacing the drier. Most manufactures recommend replacing them every three years which is overkill when the system is working properly, but if you already have the system down you may as well. I just ordered mine from cdan at a little over 30 bucks.

Also, how did you get the oil out of the compressor? Normally when I work on the A/C it's because the compressor is bad. This time its from a hole in an a/c line.

 

[zx9r]

The expansion block is attached to the evaporator core. You have to remove the evaporator housing from under the passenger side dash to change it. When you changed the condenser, did you drain any oil out of it and if so, how did it look? If if was black or has particles in it, then I'd proceed with the flush. If it was clear, I'd skip the flush. As far as being open, I'd put a drier on it and call it good. If you haven't already, put a couple ounces of PAG46 oil in the condenser and another oz in the drier. The green dye is usually put in a 1/4 oz shot, so although it looks like a lot, it's really not, unless someone got carried away.

No wonder the expansion valve wasn't obvious. I expected it to be inline somewhere. Anyway, checking the old condenser is good advice (I should have thought of that myself I suppose...). Definitely nothing black or sludge-like when I removed it but I didn't inspect for particles. I'll do that shortly and forget the flush if I don't see anything.

 

[zx9r]

Also wondering about adding the PAG oil prior to having the system evacuated and charged. The Receiver/Dryer instructions to say to pour 20 cc of oil into it before hooking it up. But if the system is vacuumed and recharged would this be necessary? Or is it just needed if you are only adding R134 w/o the vacuum and adding oil?

 

[1972FJ55]

Basically you're just adding oil to replace the oil that would be in the condenser and drier. When the system is vacuumed, it removes very little oil, but it is important to replace the oil that was in the parts being replaced. If the shop is using a recovery machine, they can measure the amount of oil removed from the system when pulling it down (usually <1oz.) and they can even add that amount back in when recharging. The Toyota/Denso A/C systems are really durable, so I'd be suprised if there's any debris in it.

 

[zx9r]

Upon further inspection, I don't see any obvious debris (although I should have thought to look more closely when I first removed the condenser and most of it leaked out onto the garage floor...). So I'll skip the flush. I'll report back later in the year if my compressor blows up on me. Otherwise, consider all ended up fine...

 

[TEXLEX450]

x2 on the evaporator replacement if your system has been open that long.

 

[zx9r]

trouble finding silicone o-ring grease locally. any thing more readily available I can safely use as a substitute? Is there really something special about the grease or is it just special labeling of a more or less standard product? Don't want to mess with this again for a long time so being careful to do it right...

 

[1972FJ55]

If you can't find the silicone o-ring lube, you can use R12 refrigerant oil, which is mineral oil. Don't use the PAG oil, it tends to sieze the o-rings.

 

[zx9r]

finally found something I think will be fine. It's plumber's lube, silicone w/ not petroleum based anything. Although marketed for faucets, etc, it does mention o-rings as well. Found it at Lowes for a little over $3.

Just put oil in condenser and dryer and reassembled with new pipe between condenser and dryer (since I've suffered a leak at the dryer connection for the second time now). Taking it to be charged tomorrow. Hopefully it will hold full pressure now.

THanks for the advice '72.

 

[1972FJ55]

It sounds like you should be set. That Lowes tip is a good one. Good luck!