Technical technical A/C

I am putting a/c in my 41 ford p/u. the vintage air evaporator housing was cracked so I am using an under dash much like the old mark 1V unit the problem I am having is I can't pull a vacuum or get it to accept Freon. sanden compressor gm drier and binary switch by passed. I know a/c is not traditional,but I am and being 71 I like my creature comforts,any thoughts or suggestions greatly appreciated Tom

 

If you can’t pull a vacuum then you have a leak


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You need to be able to pull a vacuum down to about 29-30 inches of Hg. Once you shut off the vacuum pump and gages, it should hold the same vacuum reading. If not, you have a leak, and first need to fix it before adding any refrigerant.

 

If you can't pull and hold vacuum you probably have a leak somewhere. HRP

 

Two different things. Are you trying to pull a vacuum with a vacuum pump or can you just not get the compressor to kick in and start drawing in Freon?

Pulling a vacuum on the system to insure you've removed all moisture and have a leak free system should be done before charging.

After that, you must put enough pressurized Freon into the system to "make" the binary switch and pull in the clutch to the compressor. A full can will usually do that but you can jumper the two wire of the binary switch together to get the compressor clutch to pull in, if needed.

 

I understand you wanting creature comforts, last year I finally added heat to my sedan after going 31 years without it, I used vintage heat/air and I can attest with some of the trips we took this summer, running air we were very comfortable.

I haven't used the heat much but it will run you outta the car when cranked uo on high. HRP

Make sure you didn't forget a " O " ring & check to make sure the connections are tight.

 

Pump the system full of nitrogen. Check all of your connections and all brazed joints with soapy water in a spray bottle. If you have a leak that will find it.

 

If you can’t pull a vacuum on it, assuming you’re actually using a vacuum pump (you didn’t say...), you have a leak. Don’t waste your refrigerant. Charge the system with nitrogen, get some soapy water and go leak hunting. Check every joint, then check the evaporator and condenser.

If you’re using new parts, they should be good. If they’re “remanufactured”, sometimes that just means that they hit it with a rattle can and shipped it.

I’d be concerned that your vintage air parts are damaged. If they’re new, contact vintage air and get replacements. If they’re used, whoever pulled them off whatever they were on may not have been careful not to damage anything else.



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Most times my mistake is mocking it all up. Then forgetting to install an O ring someplace.

 

Lube up the o'rings too! The oil helps o'ring slip in place and seat properly. It is easy to roll, nick, or cut an o'ring and cause a leak............I've damaged one before and had problems pulling a vacuum.

 

I think he means he can't get the system to draw in freon, not that he can't draw a vacuum in the system. He's jumped the low pressure switch and still can't get the compressor to kick on, if I'm reading his post correctly.

 

I had that problem awhile back and I think it was my can adapter as far as charging. Pulled a vacuum ok.
Might be your equipment, not your vehicle.

 

Yeah, it’s not clear. IMHO, if he’s not vacuuming it down first, it’s wrong anyway. Stop there.



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If you are using the new cans you got to have one of these. https://www.walmart.com/ip/Interdyn...=sem&msclkid=a06b1b15e6e217843c4446cc1b9528d6

 

the compressor is kicking on but cant get it to pull vacuum or accept Freon. I replaced the evaporator and the hoses from the drier to evap and evap to the fire wall. will pull apart and check orings. will report back with findings thanks for the help thus far Tom

 

That makes no sense, if the compressor is kicking on ( on its own ) then you have some freon in the system. If you are manually kicking the compressor on, then you have a valve problem either at the gauge connection or on the A/C line. Are you using the 134A to R12 system adaptors? If so, pull the guts out of the R12 valves before screwing on the 134A adaptors. O-rings will not keep it from accepting Freon, they let it leak out!
Sounds like a valve problem.

 

As sunbeam said, if you have the self sealing 134A can you have to use a self sealing can tap.

 

What kind of vacuum pump if it is an electric not one of those air powered ones check the outlet on the vacuum pump. Air coming out after its run awhile you have a leak no air when first hooked up I'd look for a schrader valve in the adapter for 134.

 

Well crap I didn’t know there was a new style can. That explains a lot. I do have two cans that are different from each other.
Thanks Sunbeam!