Charge/Evac Equipment Recommendations

Information on some common auto air conditioning topics.
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Charge/Evac Equipment Recommendations

Postby somedude01 » Fri Jul 21, 2017 10:46 am

Hey all. Haven't posted in a while. I'm looking to upgrade my A/C equipment enough to take the guesswork out of charging and evacuation and was looking for a few recommendations.

I keep reading the little cans are extremely unreliable with weighing an actual charge into a car, and I feel this is where I'm messing up sometimes. I'm able to source a 30lb R-134a cylinder locally for about $130 which seems pretty cheap to me, considering 30lbs in the little cans cost 190 ish. I had my A/C flawless last year before a shaft seal blew and now I can't get the damn thing back as good as it was. It was pulling 52-55f at idle within 30 seconds on a 95f day and now I can barely muster that on the highway after replacing a compressor with no other changes. -_-

I was also wanting to add a micron gauge and a refrigerant scale to my arsenal because I've been charging with a regular manifold gauge and cans. Do ya'll have any recommendations on good brands and where to get them? And whether a postal scale might suffice for DIY home charging?

Also, how much would old vacuum pump oil or a re-used receiver drier affect the final micron reading or performance? I currently have a 7 year old 2-stage Harbor Freight vacuum pump. This is another reason I'm interested in the gauge because a proper vacuum is only a shot in the dark for me right now and this may be where I went wrong.

I really appreciate any replies! This forum and AcKits has been very helpful for me.
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Joined: Fri Dec 29, 2017 9:40 pm

Re: Charge/Evac Equipment Recommendations

Postby snorky » Fri Dec 29, 2017 11:08 pm

the Equipment you choose will be based on your budget
Robinair makes decent gages, and micron gages but beware of the pumps as some are made in china now and have bad reviews
any scale that measures in grams up to 35lb would work i assume as long as it is accurate but you can get a good one brand new for 120.00
looking for used ac equipment has paid off greatly for myself but it takes A LOT of looking in pawn shops and private ad's. most private stuff i have looked at was being sold by someone who has no idea what it is and asking too much for broken harbor freight trash, but it only takes finding something good every few tries to add to your tool arsenal.

i use a harbor freight single stage vacuum pump that i purchased at least 15 years ago when it was not made by them , think it was a ftc made unit, i use name brand gages and a vacuum hose for the evac (their barriered) and a digital refrigerant scale, cheap syringes for oil measurements

when i repair ac that's been opened,leaked i disassemble the system completely flushing everything out and replace the dryer/ condenser if their paired filling every component with fresh from a sealed bottle pag in the proper measurement, this is very very important to do to get as much contaminant out as possible since the oil holds acids,water,trash etc assembling very quickly and slapping the pump on as soon as possible for a hour minimum usually two. be very careful as evaporative flushes cause moisture to form when evaporating so i squirt the oil in on the side i blew into as this will likely be were the least water will form if it is still in it. i never fill by pressure, i inspect the system using pressures, only fill by weight usually on the lower end of the spectrum. some of these little cars hold 8oz and if your off 1 oz it will short cycle and not remove cabin heat effectively.

how long does your compressor take to draw down the system to operating pressures from static? i find most problems are from over filling with gas/oil because the system is contaminated taking up the needed space or they used a off the shelf can containing oil and gas.

130.00 for 30lb is a fair market price for actual dupont brand 134a, the small cans are often chinese gas and 10oz
so it takes 48ish cans to make 1 30lb jug
cheap cans sell for 5.00 while name brand are 10-12 a can
just buying the cheapest cans possible its still 240.00+tax to get 30lb
after chinese gas was exposed to contain other gasses than what they claim a few years ago, i only buy dupont
i change my vacuum pump oil after every other use or when fall starts before it get put on the back of the shelf, this is super important!! it holds all of the contaminants pumped out of the system and will rust the inside of your pump, trash will ruin the vanes ability to seal also the pump gets HOT and when it cools condensation forms inside the pump.

always i repeat always drain the oil from new/rebuilt compressors they will have a unknown amount of unknown viscosity oil in them likely exposed for months/years to atmosphere by rotating the clutch by hand, i have used new oil to flush them out when purchased from the junk yard many times and often they work better than rebuilt units.
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Joined: Mon Aug 01, 2016 12:34 pm

Re: Charge/Evac Equipment Recommendations

Postby somedude01 » Tue May 22, 2018 6:25 pm

I appreciate the response even if we're both months apart. I purchased a ZENY brand scale from Amazon sometime last year and it's been perfect. I've been nice and frosty in all of the cars I've charged with it. I also picked up two 30lb cylinders of R134a for about 85 bucks each and even made a profit since I've been charging about $10/lb for family and friends. This was a steal in my opinion. I still have the same HF vacuum pump and it now has internal scaly rust since my master mechanic dad (who believes in venturi pumps, FML) was using it without changing the oil and letting it sit. I will likely replace it soon.

I still have not sourced a micron gauge but I have too many other things going on right now to justify it.

I was using a set of Mastercool gauges but said dad overtightened the fittings and ripped the orings on it. I ordered a service kit for new orings, then the damn thing was leaking at the low service valve (tested with a halogen leak detector) and was outside of warranty, so I just said screw it. My subsequent HF gauges have somehow worked better with the weird vinyl seals :roll:

I have not serviced my own A/C unit (90 Civic Si) in at least a year so I can't comment on the pressure side of it. I have, however, rebuilt a 96 Civic, 02 Civic, and 2001 Dakota all with stellar results. I'm about to do a 99 Explorer with a leak at a weld on the evaporator. I will probably change oil and do a condenser in addition to the accumulator/evap since it's been open for 6 years. (My brother is not that bright). I always drain and replace the oil from replacement compressors and measure with syringes. We'll see what happens.

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