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DonT 05-16-19 10:02 AM

How to revive a Lennox HS-18 AC
I got a Lennox HS-18-261-9P AC for free from a guy after his house fire, it was working at the time. That was 3 years ago. When I got it somebody had cut the lines. It has sat that way since. I know some of the oil has leaked out, I saw the oil stain on the floor. What would be the best way to revive this ac? What should do 1st, 2nd, etc. I would like to use it for my central ac with R290.

jeff5may 05-19-19 12:41 AM

That's a 2 ton 10 seer unit. Not super efficient by today's standards. Not much better than a window AC unit. But, I'm assuming it was donated or a super bargain. I myself would add a reversing valve, a txv, and a defrost control and turn it into a heat pump for a couple bucks and a couple hours work, but that's me.

Before you start, look at a few other threads where others have been down this road. You will need some tools and equipment, and a few instruments to get it done. Start gathering tools and practice some methods on scrap if you aren't confident.

First thing you want to do is purge the plumbing. Make sure the cut lines are not full of bugs or other crap. If so, use some pipe cleaners or qtips and brake parts cleaner to get the funk out. If you suspect the unit is contaminated with moisture or dust or rust, you can get some "burnout cure" purging juice/system cleaner from your favorite local auto parts store or HVAC supply house. Pour some into the suction line, then blow it through with compressed air. Repeat a few times. Rinse with alcohol or brake parts cleaner.

Once the lines are clean, you can go at purging a few different ways. With ozone depleting and global warming gases, you should reclaim. With hydrocarbon gas, not necessary. Just don't make a fireball if you vent to atmosphere. The pros use compressed dry nitrogen.

Seal up the lines, pressurize the unit to somewhere near design pressure, and let it sit for a bit to verify that you don't have any leaks. If the pressure holds, then you can vent the charge and pull a vacuum. If not, find your leaks and eliminate them. If you don't have a vacuum pump, and don't want to buy one, the flaps rents them out for cheap or free on the loan a tool program. You'll need a refrigeration gauge and lineset and a micron vacuum gauge. Charge, purge, charge, purge, vacuum, charge, purge vacuum. Last charge, only put in like 10 or 15 psi.

Now you can connect the copper lineset and indoor unit with confidence that it won't be contaminated by the outdoor unit. Again purge, pressurize and do leak check. Most pros pull 2 deep vacuums on used systems to make sure that it is clean and void of moisture. Last charge, switch to the refrigerant gas. If you're going to use a filter dryer, put it in after pulling at least one deep vacuum on the whole system. Break the vacuum with purge gas, pressurize to like 5 psi, breach the liquid line and quickly install the filter. Pressurize, leak check, purge, pull vacuum. Lower micron reading is better.

DonT 05-20-19 08:35 AM

Thanks Jeff. I'm sure I'll have a few(like a million) more question as this is my 1st try at this sort of thing.

DonT 06-01-19 10:46 AM

I bought a new lines set so do I need to flush the compressor and condenser only?

MN Renovator 06-01-19 03:53 PM

"That's a 2 ton 10 seer unit. Not super efficient by today's standards. Not much better than a window AC unit."

It's worse. The EER ratings on window AC units from even the previous energy star standard that enacted over a decade ago was 10.7 EER, which corresponds to about 12 SEER. The current minimum SEER rating for a central AC is 13 SEER.

You can see what the EER ratings are to make a rough comparison to SEER by looking through the AHRI ratings.

"I bought a new lines set so do I need to flush the compressor and condenser only?"

Was the outdoor units valves closed? Does the unit still have its charge inside?

If not, I wouldn't even go through the effort of trying to install this because all of the oil sitting inside the compressor has probably absorbed the oil and/or the internals of the compressor could have started to rust if the compressor has been open to the air.

If you still want to do this, you'll want to connect everything up, vacuum the system down with a vacuum pump for a good long time, charge with nitrogen to help dry things out, purge and vacuum it back down, then try your refrigerant fill. Not sure how to dry your refrigerant of choice but since you have a fresh charge going in, I'd add a new in-line filter/dryer as I'm sure the other one has used up dessicant.

WyrTwister 06-12-19 11:19 AM

Before you do all of the above ( which you certainly should ) , use a volt - ohm meter to do an electrical check of the condenser .

If the electrical is bad , all of the refrigeration testing / purging would have been wasted .

I know you said the unit was running when the fire occurred , but you do not know until you know for sure . And you still do not know for sure until you power it up and turn it on .

Did you get the indoor unit , also ? Or are you using another indoor unit ? Do you know , what ever indoor unit you will be using , is OK ?

Best of luck to you , :-)

God bless

DonT 06-16-19 11:16 AM

Hooked up and running. Question is how much R290 to put in?? I think I saw some thing about put in around 60%. I put in 2lbs 5oz, but lost some disconnecting the line( it's dam cold stuff). I check the inlet temp at the A-frame 48F with the outlet at 56F. The air from the duct was 57F and the outside air temp was 76 F. The pressures were 58/160. Any suggestions will be welcome.

WyrTwister 06-16-19 11:57 AM

Try aroung 160 psi and work from there .

God bless

DonT 06-16-19 12:53 PM

Sorry I should have been more clear the pressure were 58 psi on suction and 160 psi on liquid

WyrTwister 06-16-19 07:32 PM

What was the Outside Air Temperature , return ait temperature , discharge air temperature , suction line temperature at the evaporator , suction line temperature at the condenser and liquid line temperature ? Someone more knowledgeable than I , should be able to put it all together .

Disclaimer , I am not personally recommending anyone use propane as a refrigerant ( flammable ) .

Best of luck and please stay safe .

God bless

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