AC freon question
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Mountain Pass
Joined: Dec 2005
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AC freon question
Just bought a 2006 F350 from my company and have an ac question. Its got 113k miles on it with a new motor by Ford less than 2k ago. The ac clutch was not engaging so I checked the pressure and it was 20 psi on the low side. After 1 can (12oz) of freon the clutch would click on every one in a while. After 2 more cans the pressure is up to 30 and the clutch kicks on and the pressure goes down in about 20 seconds and the clutch cuts back off. Before I put in a couple more cans ,I just wanted to make sure I was on the right track. Should I put in some leak detector and or preventer, or just freon?
Hotshot
Joined: Jan 2004
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From: St Louis
Unless you're in the southern hemisphere, I wouldn't be screwing with an AC charge attempt unless you are using a scale to measure an accurate charge into a fully evacuated system. Otherwise, you need a very warm to hot day to get it any closer by feel.
You're already in the ball park having added 36 oz of R134 to whatever was in there to start with. You will need to refer to the under-hood label to see what the system capacity is supposed to be for your truck as-built. My guess is somewhere around 35-45 oz.
PS Ford last used Freon in 1993.
You're already in the ball park having added 36 oz of R134 to whatever was in there to start with. You will need to refer to the under-hood label to see what the system capacity is supposed to be for your truck as-built. My guess is somewhere around 35-45 oz.
PS Ford last used Freon in 1993.
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From: Home Base Nebraska
You are probably getting close but the only way to know for sure is have the gas that's in the system now removed by a reclaim machine and weighed back in to make sure it's the right amount. Being that the motor was just replaced there may be a leak at one of the hoses or they never charged it to begin with. Check the hoses at he condenser and compressor to make sure the are tight but if the O rings are bad the only way to fix that is remove the gas and replace them.
Denny
Denny
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From: mn
i've done all my a/c's myself, with the proper (r134a) coolant. I bought a a/c pressure guage from the local parts store, of course you have to add in on the low pressure side. the guage has a "normal" range in it to tell u if your in the ballpark. the reason the pressure drops is that the pump is cycling the coolant which is where u want to measure it on the low side, the instructions with the guage should tell u the rest. this system worked for me all the way back to the freon days. good luck w/ your project---if you can swing the cash-- have it done by a pro--pressures w/ac systems ca get pretty high and therefore dangerous---do at your own risk
Posting Guru
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If you're leaking refrigerant than there's no point in continually adding refrigerant until that leak is fixed. Once a system is open to atmosphere then that system, after leak is repaired, will need to be evacuated prior to adding refrigerant for optimal and lengthy results. Moisture and any possible contaminants will be removed upon vacuum.
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From: Home Base Nebraska
i've done all my a/c's myself, with the proper (r134a) coolant. I bought a a/c pressure guage from the local parts store, of course you have to add in on the low pressure side. the guage has a "normal" range in it to tell u if your in the ballpark. the reason the pressure drops is that the pump is cycling the coolant which is where u want to measure it on the low side, the instructions with the guage should tell u the rest. this system worked for me all the way back to the freon days. good luck w/ your project---if you can swing the cash-- have it done by a pro--pressures w/ac systems ca get pretty high and therefore dangerous---do at your own risk
Denny
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From: mn
If you are just adding gas to the low side and only have a gauge on the low side you have no idea whats happening on the high side of the system. If you have a restriction somewhere in the system making it look like it's low on gas then you can kill your compressor with high pressure.
Denny
Denny
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Laughing Gas
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From: Ventura co.
There is also the probability that the air gap is off on the clutch. there is a write up on how to check and fix it.. Mine was Way out. it should only be about 20 thousands
Mine was almost 60 thou out because the clutch was worn out it. kicked in and out..
Mine was almost 60 thou out because the clutch was worn out it. kicked in and out..
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From: Home Base Nebraska
yes denny, thats a good point. in the 30 plus years of diy i have not run into that myself but it certainly can happen. A full pressure guage set used by a pro is definately the way to go and safer as well. and of course as texas chain ring said about evacing for max efficiency being an excellent idea. Also to little general, try not to use high vis dye to find your leak. some a/c shops won't service equipment that has had dye in it as they claim it gums up thier equipment. good luck on your project !!!
and if it sealed leaks why was I called 
Denny
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From: Home Base Nebraska
There were commercial systems I converted over to new style refrigerants that never leaked until I changed them over and it was no fun tying to find leaks. It took all of us that did it for a living to get used to working with the new style expensive gases and oils.
Denny
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Mountain Pass
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Took the truck in to the AC shop today and I had put in 5 12oz cans. The AC man put in 1 more with dye that only shows up in uv light. The 1 more can was all it needed and there were no leaks. Where the hell all the freon went is anybodys guess. I found the mechanic that put in my new motor and he said he didn't evac the system. Oh well. Time will tell.
Moderator
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From: Home Base Nebraska
Took the truck in to the AC shop today and I had put in 5 12oz cans. The AC man put in 1 more with dye that only shows up in uv light. The 1 more can was all it needed and there were no leaks. Where the hell all the freon went is anybodys guess. I found the mechanic that put in my new motor and he said he didn't evac the system. Oh well. Time will tell.
Denny
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From: Home Base Nebraska
Denny
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