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Drawing a vacuum on a mini split?

R

RedRain

do you have a schrader valve screw driver? are your schraders tight?

did it hold vacuum at all? or did it slowly creep back to 0? are your gauge hoses nice and tight as well?

did u use 2 wrenches to tighten the flare connections?

its not good practice to depress the schrader to check if you have vaccuum, if you did have vacuum you are sucking moisture/air into the lines. you use your gauge manifold to check your pressures/ vac level.

did you get fresh oil for your vac pump? is there oil in the pump? did u watch the pump pull vac using your manifold gauges?

how cold is it outside where you are?

HVAC isnt simple, its about doing things right, one small mistake can fuck you and your system right off a cliff. You have to be very careful even when you are hooking up guages to make sure you are not introducing contaminates into your lines.

DO this first, hook your gauges up and run the pump for a few hours. MAKE SURE TO USE FRESH VAC OIL TO ACHIEVE MAXIMUM VACUUM AND TO ENSURE THE MOST MOISTURE IS PULLED FROM YOUR SYSTEM. Pull vac till -30 and close both sides of your manifold guages. Watch the needle on the left, the one that shows vac. Both needles should not move. Take not of their positions and see how long it takes for them to move. If they both move back immediately, you have a leak or moisture. Let me know about this.

If worst case scenario, you can always bring it into a HVAC place, tell them u want quick connects brazed on. Then all u have to do is connect the lines.

A tank of nitrogen is like $600 deposit, and $30 to fill it up, they might only sell to u if u are in the trade. If you can get one u also need a regulator ($120 roughly).
 
the_extremist

the_extremist

Member
RedRain said:
do you have a schrader valve screw driver? are your schraders tight?

did it hold vacuum at all? or did it slowly creep back to 0? are your gauge hoses nice and tight as well?

did u use 2 wrenches to tighten the flare connections?

its not good practice to depress the schrader to check if you have vaccuum, if you did have vacuum you are sucking moisture/air into the lines. you use your gauge manifold to check your pressures/ vac level.

did you get fresh oil for your vac pump? is there oil in the pump? did u watch the pump pull vac using your manifold gauges?

how cold is it outside where you are?

HVAC isnt simple, its about doing things right, one small mistake can fuck you and your system right off a cliff. You have to be very careful even when you are hooking up guages to make sure you are not introducing contaminates into your lines.

DO this first, hook your gauges up and run the pump for a few hours. MAKE SURE TO USE FRESH VAC OIL TO ACHIEVE MAXIMUM VACUUM AND TO ENSURE THE MOST MOISTURE IS PULLED FROM YOUR SYSTEM. Pull vac till -30 and close both sides of your manifold guages. Watch the needle on the left, the one that shows vac. Both needles should not move. Take not of their positions and see how long it takes for them to move. If they both move back immediately, you have a leak or moisture. Let me know about this.

If worst case scenario, you can always bring it into a HVAC place, tell them u want quick connects brazed on. Then all u have to do is connect the lines.

A tank of nitrogen is like $600 deposit, and $30 to fill it up, they might only sell to u if u are in the trade. If you can get one u also need a regulator ($120 roughly).
Click to expand...

I don't have a schrader screwdriver.

Used two wrenches for the flare connections, fresh oil in the pump. It was probably 45*F yesterday when I tried to vac the system. Still freezing at night, high 20's F. Northeastern WA.

All I used for a gauge was a digital micron gauge, Supco VG64. The display has a bar that moves to the left to indicate vacuum and to the right to indicate pressure increase. While drawing vac, the bar would move to the left for a while and just stop. The manual says that if it does this vacuum isn't increasing, just staying a certain value. It only reads microns when you get below 12,000 microns and it never even hit that. When I shut the valve off going to the pump, the bar immediately started moving to the right, indicating a pressure increase. To me, this says "leak." Of course, I'm an hvac amateur so I really don't know shit, haha.

I don't have a traditional gauge set and now that I'm in this situation I regret not buying one in the first place. I assumed the digital gauge was better, which was stupid of me. But now I don't trust the effing thing because like you said, I need to be able to watch the damn needle move. And now I need another bottle of oil for the pump. So I think I'm screwed until I can find a set of traditional gauges and some more oil.

I also really would like to not incur any more expense on this project so I hope the nitrogen purge isn't absolutely necessary. If it is, then it is. But fuck, I hope not.
 
R

RedRain

you might be able to get away with your oil, is it still clear?

does your pump have a vent screw? if its that cold this will need to be open. i circled the vent screw in green.

Put your finger over the fitting that you connect your hose to on the vac pump and turn it on. Does it suck your finger in?

your pump should have a switch to block the flow, so when you turn off the pump, you wont suck air back inside. do you understand? if the switch is up its open, when the switch is parallel to the pump its off.

i wonder if you just let air be sucked back into the system.

i circled the valve in red that closes and open the valve to allow vacuum. you want to close this before u turn off the pump to see if u hold vac.

if you left the coverings on the end of the line until you screwed the line together I dont believe u have moisture in the system. Was is raining?
 

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the_extremist

the_extremist

Member
Yeah, my pump has one of those vent screws but I didn't know it needed to be open. I will try that. The pump I have does not have a valve, but I have a hose with a ball valve on it between the swivel tee and the vac pump so I could do exactly what you mentioned.

Would not having the vent screw open cause my problem?
 
R

RedRain

take a pic of how your hoses are connected. is the ball valve after the swivel t closest to the condenser?

remember that you need to stop the air from coming back in, but you also need to read the vacuum on your line.

you should have the vacuum gauge hooked onto your open base valve, the opposite line of the one you are vacuuming down. since your compressor is not open, you are just drawing a vacuum through your indoor unit and txv. only draw vac from say your larger line, and have your vacuum gauge reading your smaller line.

take a pic for me if u can.

i don't doubt that opening the valve is your issue, but it will assist your pump in starting and drawing vac in cold temperatures.
 
the_extremist

the_extremist

Member
I don't have a camera, but I can describe it for you.

The female side of the swivel tee is attached to the male fitting on the micron gauge. From one male fitting on the tee there is the yellow charge hose with the ball valve going to the vac pump and from the other male fitting there is a plain yellow charge hose going to the schrader port on the condenser unit. So I can shut off the connection to the pump, but the gauge and the A/C system is still on the other side of the valve so I am assuming it's reading the vacuum correctly.

I know this is a funky setup and I would be very happy if the problem was as simple as how I had the gauge and hoses setup. Do I have it set up correctly?
 
R

RedRain

hmmm yea it sounds correct. make sure all your connections are tight. try again with the vent open.
 
G

Guest 18340

RedRain, even if he has quick connects brazed on he will still have to have a vacuum pulled the first time they are connected.
Braze-connect-vacuum.
 
R

RedRain

evlme2 said:
RedRain, even if he has quick connects brazed on he will still have to have a vacuum pulled the first time they are connected.
Braze-connect-vacuum.
Click to expand...

The whole point of quick connects are that they are SEALED. If they are not connected they contain the refrigerant as a liquid or a vapor, and they will hold vacuum as well.

evlme2 - Please dont comment on things unless you know, it just confuses people.

ya, an hvac company will braze on the quick connects, pull a vacuum, pressure test, test the system etc.




further more, you are not an HVAC tech.

its goes

braze-pressure test-vacuum-connect-test system

by recommending him to an HVAC company, he has a professional doing his job. its such a simple install and procedure for a tech, but I am sure he overlooked something small, or if he has an issue he is not equipped to deal or solve it. So I gave him the more logical thing to do, have a pro do it.
 
G

Guest 18340

Funny that I'm no hvac tech yet I've installed mini splits without ANY issues.
Also, it's pretty obvious that by him coming to the boards for install help that he doesn't want to or can't have a tech do the work.
Leave your 'tude at the door...
Oh, and I'm well aware what quick connect fittings are and how they work. You've mentioned in at least two threads to have quick connects brazed on but you never mentioned that the line set will still have to be vacuumed a first time.
 
R

RedRain

Ya so u installed a simple mini split yourself do u want a gold star? They are simple enough for anyone to so but when u have a problem that's when u need a professional because u don't have the knowledge or the tools to solve an simple issue that a pro could fix.

If u don't know to vac down lines or quick connects after brazing then u don't know enough about AC work.

I also mentioned to take it to a pro to have them braze on quick connects, so the company would have already pressure tested , and pulled vac.

U are a tool buddy !!
 
G

Guest 18340

Yup. A tool that knows how to install his own mini splits. No "pro" needed:tiphat:
 
R

RedRain

wow big deal!!

its when problems occur its over and above the consumer.

they make them easy enough to install, trouble shooting or problems is a whole other ball game.

I was simply telling you to not comment on things that you dont know, cause it confuses people. If you are just posting to have a pissing contest good job. I am trying to help the OP.

Stick to nutrients and ferts!!:dance013:
 
the_extremist

the_extremist

Member
Well fuck. I drew vac for over three hours and the micron gauge still doesn't read a good vacuum. I'm gonna try and find a traditional manifold gauge set to make sure this digital gauge isn't just a piece of shit.

I'll keep you all posted.
 
R

RedRain

a guage set will help you to see that you are not holding vac, but its still gonna be hard without nitrogen. Lets hope its that u have a shitty micron guage.

Let us know, a tank of nitro and a regulator would be nice. They also sell a great leak detector called big blue that is almost a jelly substance that makes it really easy to stick to pipes.

i know i asked this before, but did u make sure all your connections were tight?

did u check that the pump is even pulling vac by putting ur finger over the hole while turning it on? does the pump have a hollow gurgling noise, that gets less hollow as time goes on?

get some new vac oil while u are at it
 
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