Repaired Air Conditioner, Can't Get Refrigerant To Enter

My air conditioner was working fine. Then it slowly started to become less cool. I inspected and found a leak at the compressor high pressure line. I replace the crush-washer/seal on the high and low pressure lines. I connected my gauges, pulled a vacuum (it held), vacuumed the system for over an hour, connected the new can of refrigerant, started the engine with AC on and opened the low pressure side valve. Nothing happens. I did some trouble shooting and am sure refrigerant can make it through the gauge set. The compressor never engages to start sucking it in. I checked the AC fuses (two under the hood) and their good. I am a mechanic (but don't service AC too often). I did watch the ChrisFix video and am pretty much following his directions. Any ideas?

 

Are you using a real manifold gauge set?

 

It’s been an eternity since I worked on AC but... Don’t you have to jump the low pressure cutoff switch to get the compressor to kick on?

 

I had the same thought. It's been a long time since I've had to do any a/c work but almost certain I had to jump that switch to get the compressor to kick on .

 

Thank you for the replies.

• Yes, I am using a real set of gauges for R134A (red hose, blue hose, yellow hose, etc)
• I had not thought of jumping the low pressure switch, I though it would trip as soon as some of the refrigerant from the pressurized can entered the system, I will give that a try next chance I get (hopefully tomorrow).

 

You shouldn't have to run the a/c. It won't run anyways due to the hi pressure switch seeing no pressure. The vacuumed down system and pressure of the a/c refrigerant supply source should charge the system. When the pressure switches see enough psi the compessor will engage.
Only the old R12 systems I delt with required the compressor running to draw freon in.

 

I dont have much experience with the cans because we have a big 'ol machine at work.. but there should be enough pressure in the can to push some in there and get the compressor going. Are you sure the can is opened and connected correctly?

 

OP you have the truck running with the ac on max? And you are filling from the low side correct. FYI the compressor should be running.

 

Are you using the correct can tap? The newer self sealing cans require a self sealing can tap with a flat tip. If you use the incorrect can tap refrigerant won’t come out.

When I filled my system starting from empty it took about 5 minutes of filling until the compressor kicked on. The low side was about 15 psi when the compressor kicked in.

 

• I too would have thought the vacuumed system and the pressure from the can would push enough refrigerate into the system to trip the switch and start the compressor.
• I do have the truck running with the AC turned on, the fan speed is not on high, but the AC is on and on recirculate. I am filling (or trying to) from the low side.

 

Lets see a picture of your setup. The charge can is on the middle hose correct?

 

This is the correct answer above. I experienced this yesterday when I installed a new condenser. By fiddling with the can tap I finally got it to work. Look at your can tap. Pointed or flat piercing?

 

I just had the same thing with my corvette. The compressor must be engaged to accept a charge...………….

 

This is exactly what should happen once enough refrigerant has entered the system the compressor should kick in.

 

The valve on the line is not intuitive, the valve turns right goes down and opens the seal.

 

It'll take a can, or close to it before the compressor kicks on when recharging. Mine did when I replaced the expansion valve.

 

The cans of refrigerant I have are the self sealing type. It looks like that is all you can get these days. The can tap I have is old and is for the old, non-self sealing type of can. It looks as though that is why I cannot get the refrigerant out of the can. Although, a little bit will come out when the tap is it the correct spot. I will get a self sealing can tap and try again this weekend and post an update. I do appreciate the help I have gotten from the forum. You guys are very helpful--thank you.