dlaw7822

I am in the process of rebuilding the a/c system in my '64 coupe. Is it possible to flush out the evaporator without removing it from the car ? (no leaks ) concerned about removing all of the flushing solvent so as not to comtaminate the new components. Really trying to avoid pulling the evap. Thanks, dave.

Nowhere Man

If you have your car torn apart. Like all the interior out and the engine out I would pull the heater/ac box from the inside and the evaporator box from the out side and rebuild and restore them both. Both are easy to take apart and rebuild. In the end you will have a better working AC unit.

Powershift

Not certain that the evaporator needs flushing...............maybe just a good blowing with 30 psig dry shop air to remove any oil/residual. I would keep pressure below 50 psig or so.

The evaporator should have a lower inlet and a lower oil drain line (back to STV) which should allow any flushing material to drain out.......especially if you use a bit of air pressure at the evaporator core outlet to push it thru. But I would consider not flushing it out at all........just an air blow thru it.

FWIW.

Larry

Mike Geary

with Larry. Low risk of particles in the evap, given the inlet filter on the TXV.

dlaw7822

Thanks N. Man. I drive the car a few times a week. If I was 30 yrs. younger , I would disassemble accordingly but the car is in exceptional condition throughout so purging with compressed air, for me, is a better option. I might be wrong, we'll see.

dlaw7822

Thanks all for your advise. Will blow air in one end and catch any debris in a clear container on the other. Ya'll made my day !

Nowhere Man

like I said if it was tore apart I would do it. if its a complete running car then no I would not do it unless there was a problem. so I would do as Larry suggested

pop23235

Having done a lot of AC/refrigeration work, blowing compressed air into or through a sealed part of the ref. equipment is a big NO NO. Flush with appropriate solvent only (if you must, but not likely needed!). If you blow through it, use dry compressed nitrogen. But, correct solvent will evaporate for sure when you evacuate the system.

Powershift

The compressed air won't hurt a thing. I agree that (dry) nitrogen is the preferred gas to use for AC system purging and checkout, but almost no one has this at home. Dry shop air is sufficient.

What is the downside?? A little moisture in the air/gas?? Any remaining (unlikely) will vaporize when you close up the system and evacuate it.

Although your car/Corvette AC system is well designed, it is NOT a commercial refrigeration system that requires a special level of care and attention. Just follow reasonable practice. Close it up, add your oil, pull a DEEP vacuum on the system for a few hours or overnight and recharge it. Install a rebuilt/new drier per good practices. It will work just fine.

Larry

pop23235

Just depends on how many years later you want to replace the evaporator coil.

Powershift

POP23235:

Don't want to be argumentative............but please explain further how having air with perhaps high humidity (i.e. dry shop air) will cause the evaporator core to corrode, once the core has been properly blown out and then evacuated??

Moisture can and will cause aluminum/metal corrosion in an AC system if it is left in there and reacts with the acids, etc generated by decomposition of the refrigerant over time. What about new cores that are shipped open?? Or a core that sits open to the air for a week or so when the owner is ordering and replacing parts??

The WORSE thing a person can do for these systems is not do a proper evacuation or not replace the receiver/drier desiccant after the system is open. The desiccant itself will pickup and hold approx 1-2 teaspoons of water from the typical C2 AC system..........but you don't really want to rely on this.

Don't scare the OP and make him do something that is not required for his situation.

Larry

pop23235

Not argumentative at all. You answered the question in your post. Pinhole corrosion will require replacement down the road. It will show up in the evap. Best shop practice is keep the moisture out. They are shipped sealed with plugs. After the box is opened, it's all about shop practice. I've never left a system open for more than a few minutes. Not saying some don't get away with it...for a while.