Using a bicycle pump to find AC leaks.

I would fill it up with r134a at five dollars a can from walmart dot com and add some dye. The leak you are describing sounds pretty big to me.

Or take it to a shop if you are environmentally sensitive.
Highly irresponsible if not illegal. It leaks down in no time flat.

Being aware of the combustion concerns, I’ve tracked leaks with 12a HC refrigerants. But much care is necessary.

Release of a CAA restricted product is a non starter.
 
I have a substantial leak in my 2001 Honda Civic. I though it was the service port valves, since when I undid the service port plastic caps, some gas hissed out of them. I ended up replacing a pipe, because new valves were still hissing in the pipes. I suspect corrosion did them in. With the new pipe, there is no more hissing.

Pulling a vacuum showed a gradual leak to ambient pressure in about 30 minutes. That is too large a leak. I know conventional leak detection is pumping refrigerant into the lines with perhaps a dye leak detector or chemical sniffer. I have found neither of those methods as accurate or successful as I’d like them to be. I also am uncomfortable with using expensive and environmentally harmful Chemicals as a leak detection tool. R134a prices have also shot up. It was $17 for a small can.

Vacuum isn’t so great for determining where the leaks are - pressure is. I don’t own an air compressor, but I thought, what about using my simple and effective bicycle pump? I use that manual push pump for inflating my car tires to 40psi. Perhaps I can pressurize the AC lines and use the soap and bubble method to fine leaks.

I have already sourced a shrader valve to NPT 1/4” on Amazon. It’s only $8. I can use an adapter from NPT to get to gauge set threads. Then it’s just a matter of pumping air in until I get 40 or so psi, and spray all over the system to find leaks.

Anyone ever heard of this? I will post pictures on Friday, when I plan to do this.

Did this recently. Was messing around with a car with an evaporator leak.

 
Highly irresponsible if not illegal. It leaks down in no time flat.

Being aware of the combustion concerns, I’ve tracked leaks with 12a HC refrigerants. But much care is necessary.

Release of a CAA restricted product is a non starter.
Yea, the new R-1234yf machines include a leak detection mode - if any loss is detected during the evacuation and pre-charge phase, the charging process is aborted. Part of the new rules for motive HVAC. The new stuff is expensive, it’s $70-80 for a 6oz can.

The irony is that professional mechanics must take a EPA 609 course and pass the test(maybe also a MACS certification) to be allowed to work on HVAC but anyone can buy a can of AC Pro or virgin R-134a/R-1234yf and DIY it without checking for leaks or recovering an existing charge.
 
Can you borrow an air compressor from someone for the purposes of checking for leaks?
Also, I wouldn't worry about introducing moisture to the system since you are going to put the system in a vacuum before you refill it.
 
I think everyone’s favorite purveyor of Chinese tools(Harbor Freight) also sells leak detectors as well. It may be worth adding a wisp of R-134a(which is getting more expensive by the day, CA charges $10 for a refundable deposit) and using one of those for places for you can’t see.

Emphasis on may since their leak detectors don't work. I had way better results using compressed air, or just just assuming it was the compressor (which it was both times).
 
Thought I would let you guys know this method worked. The leaks was at the compressor, the hose from the condenser to the compressor was leaking. Soap and water bubbles were obviously there. Swapped it out and installed a new dryer. No decrease in vacuum over 15 minutes or so.

I vacuumed for 20 minutes, recharged the system. Works fine now. Now that I have the equipment, I will never have to buy more refrigerant to find a leak again anytime soon! Unless it is a failure within the dash or other unsprayable area.
 
Most shops don't vacuum long enough. The robinair units most shops have are factory set for 15 minutes. Any longer and they burn up!

Maybe he can find a shop with a different machine or a portable vacuum pump that they can leave running while they go to lunch?
Unless the accumulator/dryer has been exposed too long to moisture. Vacuuming won’t help. More than likely the leak will have to be repaired and dryer have to be replaced, then vacuum the system and add Freon. Should cool as designed then.

Edit: I see that’s exactly what was done. Good work.
 
Unless the accumulator/dryer has been exposed too long to moisture. Vacuuming won’t help.
The only way to “recover” a dryer is to “bake” the desiccant above 200-300 degrees Fahrenheit. Which also destroys the plastic sock the desiccant sits in.

However, a 10 minute vacuum is SOP by many shops, they stick to the defaults in their RRR machines.
 
I like the price but I noticed there are 1/2 horsepower and even 1 horsepower units out there. Would it be the degree of vacuum that it can pull that is affected by horsepower? I assume the pro shops want to minimize the time it sits and therefore might want to pull a higher degree of vacuum. For home use, if 1/4 HP is enough ( with a longer wait time ), I’d be OK with that . Any opinions on that? Thanks.
 
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I like the price but I noticed there are 1/2 horsepower and even 1 horsepower units out there. Would it be the degree of vacuum that it can pull that is affected by horsepower? I assume the pro shops want to minimize the time it sits and therefore might want to pull a higher degree of vacuum. For home use, if 1/4 HP is enough ( with a longer wait time ), I’d be OK with that . Any opinions on that? Thanks.
I think that pump or any available at Harbor Freight are fine for DIY automotive applications. I used a 2.5 CFM / 75 Micron Harbor Freight pump on my Scion compressor replacement. I let it run for half an hour. First few seconds had a little moisture coming out of the exhaust port. I stopped after a while, closed the gages to see if the system would hold a vacuum, and ran it again.
 
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