My 1990 f 150 had no AC since I got the truck. Mechanics said $200 - $400 to change to R134
And replace high pressure lines. Compressor seems to work ok. I had a crazy idea of finding a nameless refrigerant on the Internet and charging it myself to see if it might just need to be charged. I attempted to vacuum out system and added charge and it actually blows cold air now😀 my fuse blew since it was a 15 amp should be 30amp but all went as was supposed to as soon as I started filling system compressor engaged. Is it normal for the compressor to go off and on often it should it stay on longer if Ac is on full?

 

Compressor should cycle quickly at first when charging but then stay on after system is full. It may cycle periodically if the fan is on low, but at high fan speed, which you should be on during charging, the compressor should not cycle if full.

 

Thanks that really helps!

 

My AC is working I hear a strange noise when I shut off truck like a pressure release sound also there is condensation on AC lines is that normal?

 

Condensation is normal and that sound is normal as well.

 

if all you did was changed the lines , pulled a vacuum , and added R134-A, plan on loosing everything within 1 years time. your 92 is supposed to use R-12 and by putting R134-A in it without doing a conversion it will self destruct in a short amount of time.

 

Hmmm doing a conversion he will change dryer ,compressor and oriface tube and flush system so if it destructs in a year he did make it one more year

 

Sorry for the confusion no conversion was made the system was recharged with R12

Thanks everyone

 

R-12, ok. properly repaired AC.
from your first post it sounded like you used R134-A

 

Thanks looking back I can see why it was thought I used 134.a mechanic wanted to re do everything I just wanted to add
r 12 and see if it works. And a couple weeks later it's still holding up.

 

Shush that talk and don't let my 89 Ranger hear such things! I recharged the system with 134A eight years ago and didn't change anything, just vacuumed and recharged with 134A.... I'm not recommending this but I can still run the fan on low and freeze myself out of the truck and only lose 1/4 can a year. I do have a spare bigger compressor pump sitting on my shop shelf anticipating it's failure and did have the part numbers for full the conversion but it's still blowing ice cold air.

 

the problem is not with compressor failure, the problem is that R134-A is not compatable with the oil used in the R-12 system, and it almost always turns to a black sludge crud that plugs up the orifice tube and other parts, causing the system to self destruct.

 

Good 'ol "Black Death"!

 

yuppers, that would be it!!

 

X2.........

Not a fan of the R134a conversion unless you completely flush the system. And in most cases consider a later model condenser.