AC System Flushing

I have flushed out many AC systems for vehicles, tractors, and even homes with nothing more than regular starting fluid. It dissolves and removes the old oils and sludge that may be present the system as well as flushes out any particulates or debris as well.

I just keep pushing it through the system with a little air pressure until it comes out clean then pull the system down to a high vacuum to boil off any remaing fluid then add the new oils and refrigerants. so far I have never had any problems afterwards even when doing R12 to R134a conversions.

It may not be the best solution but its cheap and easy to while giving favorable results in the end.

Heh, I'm sure you're feeling no pain with all that ether floating about too....=b

Just spoke to a co-worker whose dad is an HVAC guy and for residential service where they are re-using lines that were originally part of an R-22 system over to R-410 service they used to use R-11 as the flushing solvent, but that is no longer allowed because it is a CFC, there are a number of HCFC alternatives on the market these days that serve the same purpose, but it would appear that R-134A is commonly used itself. the downside is that I'd have to reassemble the system for that and contaminate all the new bits. since i'm essentially only keeping the aluminum evaporator and condenser coils and replacing the rest, I'm thinking that a simple can or three of brake cleaner with a straw nozzle inserted in the open end of the tubing and a piece of rubber heater hose on the other end directed down into a bucket followed by a lot of compressed air should work fine.

If you do use the starting fluid, DO NOT SMOKE!!!!!!!!!!!!!!!!!!!

The store you get the compressor from will sell A/C flush. If you have a siphon sprayer, or a paint spray gun, they will work well. Remember the direction freon is flowing during normal operation. You flush backwards. Use paper towels or light colored shop rags to determine when the flush is coming out clean. I have my concerns about reusing the old freon, as there is no filtration in your system as described. Just use new freon. I prefer to separate as many components as possible when I flush, but that is just my personnel preference. Good luck.

I am surprised that no professional told you.. Using brake cleaner will clean out 1/1000 of the surfaces inside that system. Only a full fluid flush and backflush will clear most of the condenser and system. If you "flush" it yourself without the proper fluid or equipment you will be wasting your time and money. If the small debris is left in there your system will work for a while, but eventually those contaminants will destroy your new compressor as well. My advice is to put everything together, then before you hit the A/C button, take it to a shop and have them professionally flush and fill the system anything else is a bad idea.

how do you know that it was not the clutch on the front of the compressor that froze. The clutch is external. Did it throw a belt ?.You could take a line off of the compressor and dab a swab in to it to check for gremlins. .02

If the compressor itself seized before destroying the clutch then the particles in the system will likely be just fine aluminum powder from the moving parts in the compressor as it ate itself.

Back flush the system with a commercial a/c flush solvent, available at a good auto parts store. Pick up enough O-rings to replace all that were encountered when when disconnecting hoses, components and pipes. Be sure that they are R-134 compatible.. Lubricate them with PAG oil and install as needed. Use fresh R-134. Remember that a fair amount of refrigerant will stay in the gauge set hoses even with the the motor running and compressor started. Verify the quantity of PAG oil to be used. Use the proper viscosity of PAG oil according to Toyota. I believe they use PAG -100, but check.

All else seems in order.

Bob

wouldnt the cluch just free wheel then ???.When the a/c or the defroster are off the internals of the compressor are not moving,the cluch free wheels. .03

When the compressor seizes with the clutch engaged often the belt is tight enough to cause the clutch plates to slip enough to weld themselves together. The heat usually causes the coil to overheat and burn up, then blow the fuse.

Bob

That would appear to be the case. The potting compound on the coil has melted and has oozed out, the compressor is seized, the clutch is freewheeling and pops the fuse within seconds of replacement.

you need to use the correct flush liquid to get all the particles and burned ac oil out of the condensor and evaporator, the reciever drier will need to be replaced, you will need to put the correct amount of oil back in the evap and condensor as well as the receiver drier, fill the pump with the factory spec amount and hook up the hoses, pull the vacuumn for a couple hours before filling with 134a to the factory spec,

I used to have a flush kit that was a alum canister you filled 2/3 way with the flush solvent and add air press, it had a hose and nozzle with a trigger to fit the line and flush took a couple of pints to get system clean but it is the only way I would put costly hardware on the car, you may want to let a ac shop flush the system for you, the reciever drier has a sock in it for protection but it works not well enough to take a chance on particles scoring new pump. Good luck

Sincerly
Mitch retired peugeot mech

Look, don't waste your time on store bought flush. There is a reason why the right machine to flush your a/c system costs thousands of dollars, granted some of it is for refridgerant collection. Having a mechanic flush it isn't expensive and is cheap insurance. I guarantee that whatever you buy at Autozone will not have the ability to pulse flush your system.

On 6.) you'll want to recharge, using the vacuum in the system, into the high side with liquid, then put what didn't go in through the low side as gas while running. Be sure to hold the vacuum a long time to boil the water.

Ya I really miss R11, that was GOOD stuff. Let us know what you did to clean the system, like that starter fluid idea. I bet all those telling 'only' their machines can do it right don't even know why they call 12K Btu's a ton.

Normally I would be putting liquid into the high side port. My thinking on pumping gas into the low side port with the pump was that by forcing the R134A to boil off into a gas, any particulates that were either in the bottle, or transferred from the old system would be left in the bottle as the refrigerant boiled off. But I've decided to not bother trying to recover/re-use the old refrigerant and just use new. It eliminates the possibility that water vapor, or particulates or decomposed oil residue, or god only knows what else doesn't get reintroduced into the system. Better safe than sorry. R134a, isn't cheap, but it is certainly cheaper than a new compressor.

I have decided to use a siphon sprayer and a couple gallons of Isopropyl alcohol for the flush with a large quantity of compressed air behind it for the flush. I am confident that I can get the system clean (this is not terribly unlike the process I've used to clean microhydralic systems for downhole tools which also use a glycol based fluid down below NAS class 6.). I will be replacing the hoses, the expansion valve (that will be a stone cold PITA because I have to take the dash apart), the dryer, and the compressor. therefore only the aluminum coils will be the only parts of the system that will not have been replaced with new components, so right off the bat, the amount of particulates to be flushed is a small percentage of the total amount simply because a bunch of them will have been chucked with the old components. If the coils are plain old smoothbore tubing then that makes cleaning them that much simpler. If they are rifled or finned like some newer residential/commercial HVAC coils are, that complicates the issue considerably and may make getting them clean impossible. I am hoping that is not the case. If that is the case, I may contemplate using soapy water first, followed by a clear distilled water rinse, followed by a compressed air blast, followed by an alcohol wash and another compressed air blast. Not sure if that will get them clean or not, but I'm hoping that the sheer volume of high velocity solvent media will be enough to dislodge all but the smallest, most entrapped particulates. Another saving grace is that the drier has a bag type filter integrated into it which will tend to trap any particulates that may be left in the system.

The unit uses ND-8 oil per the under-hood label, which from my research is a PAG46 oil, not PAG100 as another poster thought. Almost all of the Denso compressor systems use PAG46, only the TV and the 2C series uses PAG100 near as I can tell from the data I have found.

This is what your expansion valve should look like. It may be attached to the outside of tour truck.

From the Toyo Sevice manual I've obtained it would appear to be in the evap core air plenum box (bolted to a bracket welded to the evap core itself) which is behind the glove box in the dash. Of course I haven't had the dash apart yet so all I have are the line drawings in the poorly scanned manual I've found, so the validity of that information is still suspect. I'm hoping I can replace the valve without removing the core which would entail pulling everything through the firewall. That is going to suck pretty hard if I have to do that.

"No plan survives first contact with the enemy." that saying applies to repair plans too...

It appears you have most of the basics covered. However, I'm surprised no one has suggested installing a cleanup filter immediately upstream of the compressor. The cleanup filter will trap any remaining particulate which could harm the compressor. It will also save your permanent filter from getting loaded up. Leave the cleanup filter in for a week or so of regular A/C operation, then take it out & toss it.