Air Conditioning
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From: Buffalo
Air Conditioning
Getting the AC going on my 84. I've done this 100 times on other vehicles but I just need to verify something. Does this system really take 4 cans of refrigerant? According to the sticker, it equates to 4.3 cans. Just seems like a lot. Anyways, I got 3 cans in and the air was quite cold (not where it should be, but cold). Started putting the 4th can in and the air got significantly warmer. I was in the garage doing it and I may be answering my own question here but i know air flow in front of the truck as in air coming through the condenser needs to be good. I was pulled into the garage. Maybe this has something to do with it? It just seems like the longer it ran, the less cool the air was.
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From: Buffalo
Sticker says 3 lb 4 oz R-12. I'm using R-134a. I typically just charge till air is cold but I'm used to working on R-12 systems; I know with 134 it works most efficiently when RPM's are higher so I'm sure I can't use that method when charging in the garage.
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From: Virginia
I looked it up on Autozone's site and they sort of agree with your sticker, they say 54oz. That's seems like an awful lot of refrigerant, I would put one can less of 134a in it. I think your cold theory works ok, some people use a thermometer in the outlet vent to help determine the amount to use.
Did you put the system on a vacuum for a little while before you charged it? If it has some moisture in the system, it can freeze and block the orifice and stop cooling. Also check the gap on the clutch. More refrigerant means more load and if the gap is too large it can slip or not engage. Off the top of my head again, I want to say the gap is .014-.030.
Did you put the system on a vacuum for a little while before you charged it? If it has some moisture in the system, it can freeze and block the orifice and stop cooling. Also check the gap on the clutch. More refrigerant means more load and if the gap is too large it can slip or not engage. Off the top of my head again, I want to say the gap is .014-.030.
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From: Buffalo
Thanks guys for the help.
Fleet Mechanic
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As the engine gets nice and hot, the radiator starts to back-heat the condenser, so condenser effectiveness drops some.
A big box fan on high propped up in front of the truck can help simulate road air flow (well, better than not moving).
Also need a good fan clutch.
A quick way to see if you are condenser-limited is to spray some water from a hose on a conical fan spray into the front. Don't drown it, just a fine even spray will do. If head pressure takes a big drop, then that usually shows its an airflow problem, or an overheated engine. Good way to test a bad fan clutch.
Around here (TX), R12 to R134a conversions don't work well. The R12 condenser is too small for 134a. Cools OK at sustained high speed, but stop or slow in traffic, and ya cook.
I assume you switched to ester oil.
A big box fan on high propped up in front of the truck can help simulate road air flow (well, better than not moving).
Also need a good fan clutch.
A quick way to see if you are condenser-limited is to spray some water from a hose on a conical fan spray into the front. Don't drown it, just a fine even spray will do. If head pressure takes a big drop, then that usually shows its an airflow problem, or an overheated engine. Good way to test a bad fan clutch.
Around here (TX), R12 to R134a conversions don't work well. The R12 condenser is too small for 134a. Cools OK at sustained high speed, but stop or slow in traffic, and ya cook.
I assume you switched to ester oil.
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From: Buffalo
The retrofit was already done when I took possession of the truck. It appears to have been done correctly but who knows. I always thought Ester was to be used when retrofitting but NAPA says use PAG. Needless to say, I haven't added oil to the system.
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From: Virginia
From what I understand, if you clean the old system out really good that used r12 originally, you can use PAG. Most of the 134a systems I have run into that came that way from the factory do use the PAG. But I have heard that if you put the PAG in a system that has the old r12 mineral oil still in it, that something happens and it's not good.
So most retrofit kits use Ester oil. It doesn't react to the old r12 mineral oil, so you don't have to clean the system out like you do for PAG.
So most retrofit kits use Ester oil. It doesn't react to the old r12 mineral oil, so you don't have to clean the system out like you do for PAG.
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From: Sheffield, AL
I don't understand it, but it works...
You are correct, Franklin2, but sometimes everything "wrong" is done and yet things work!
Case in point... 8+ years ago, I purchased my 1986 F150 from the original owner. It was still painfully original [original plug wires, hoses, etc.]. The A/C did not blow cold and the original compressor clicked on and off rapidly. I asked the seller and he said several years earlier, he had quit adding Freon [R12] because it was just too much hassle.
A friend who knows more than I about this did a "dirty" conversion. The system still had some pressure, so was not evacuated. By the way, it still had/has the original dryer. Conversion fittings were installed, a can of PAG was added as well as ~2 cans of R134. The old oil was left in the system, so of course it is taking up space which would have been Freon. Anyway, the A/C began to work and work well. Each of the next two Summers, 1 can of R134 was added and for the last 3+ years, none has been added and it still works well.
Go figure!
Case in point... 8+ years ago, I purchased my 1986 F150 from the original owner. It was still painfully original [original plug wires, hoses, etc.]. The A/C did not blow cold and the original compressor clicked on and off rapidly. I asked the seller and he said several years earlier, he had quit adding Freon [R12] because it was just too much hassle.
A friend who knows more than I about this did a "dirty" conversion. The system still had some pressure, so was not evacuated. By the way, it still had/has the original dryer. Conversion fittings were installed, a can of PAG was added as well as ~2 cans of R134. The old oil was left in the system, so of course it is taking up space which would have been Freon. Anyway, the A/C began to work and work well. Each of the next two Summers, 1 can of R134 was added and for the last 3+ years, none has been added and it still works well.
Go figure!
Tuned
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From: Rockford, MI
R134 systems are touchier than R-12, and if you have the amount off, low or high, it won't work optimally. Sounds like you're not entirely precise here. I have also done r-12's in the past, but the longer I live, the more I realize that a 1973 Impala or a 1982 Buick are way different. Orifice tubes can clog, evap/driers can go bad, etc.
AC systems are 50/50, sometimes ya get lucky, other times you have to pay.
AC systems are 50/50, sometimes ya get lucky, other times you have to pay.
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From: Houston
I never saw this mentioned in here but when you are running R134A remember to fill your system to 70 to 80 % of what your R12 specs are listed on sticker.
If you have too high of pressures from being over charged your 134A will not cool.
So if you have 48 oz for instance as a full charge for R12 I tend to start my charge at work off at 33 oz and slowly work my way up to 38 oz of R134a and adjust for optimal temperature. Generally 70 to 80% charge is right but some times you have to use less or more to get the system to actually cool depending on variables.
If you have too high of pressures from being over charged your 134A will not cool.
So if you have 48 oz for instance as a full charge for R12 I tend to start my charge at work off at 33 oz and slowly work my way up to 38 oz of R134a and adjust for optimal temperature. Generally 70 to 80% charge is right but some times you have to use less or more to get the system to actually cool depending on variables.
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