A/C refrigerant amount

Just to be clear. I don’t claim to know all. I’m here to learn. A/C is so complicated. Always learning more. Been doing my own since 1997. Along with a few jobs for friends, and family, to save them money. The guy who invented it was a genius IMO. Still no answer to the amount. I’ve read somewhere on here in the past. I believe Pete’s take more than my Freightliner. Maybe 5 lbs. Someone knows, hopefully they’ll chime in.

 

Everything I find says 4.75-5.00lbs with a bunk. 3.0-3.5 for daycab. Low side of at least 30lbs, up to 50lbs. High side 200 lbs normal. Just what I’ve read.

 

The coldest I've ever seen 134 is 41*
The coldest I've seen 12 is 34*

1. The last truck I drove has a bad low pressure switch. It runs at 5 psi. And never freezes.

The current truck shuts off at 8 psi.

If evaporators froze up from low refrigerant. They'd be freezing up during the charging process. Your system is empty to begin with.

The 134 cans barely get cold as they're drained empty. The 12 cans would freeze up AS they're drained.

I've seen 12 evaporators freeze as they get close to full then thaw out.. 134 evaporators get wet only then dry.

You guys on the east coast accumulate so much humidity that your box fills up faster then it can drain. Florida with it's very high humidity. Is the worst. When I was down there. I literally had steam blowing out my vents.

 

So I can use 134a in my 87 357? It has r12 in it now but that stuff has gone sky-high. Get 134a 30 lb kegs for $86 lol. It doesn't have crimp on fittings it has the barbed fittings with the worm clamps

 

Pet's that came with R12 work well converted to R134A. The last R12 I knew of on the market was $800 a jug. The last deal on R134A to me was $280 a jug for 3 or more. You are probably looking at some knock off crap.

 

I used one of these kits on my 92 WS. It worked great. Murray’s had it on sale for $5 add 4 or 5 cans at another $5. Whole job was about $10. Dealers were doing conversions, charging by the hour. Fully flushing the system. Changing compressor, silicone o rings to viton o rings, changing regular hoses to silicone hoses. They claimed the 134a would destroy the silicone o rings, and seep through and destroy the rubber hoses. Never understood why it didn’t destroy the new silicone hoses. Big bunch of BS, conversion job in 1998 at Dealer was $1000.I already had everything new, hoses, condenser, when my compressor locked up. New 134a compressors don’t have fittings. Fittings are inline. Looked like I needed new lines along with the new style compressor. I was explaining all this to my brother in law. He was a Manager at Murrays (now O Reilly’s) . He tells me BS, we have the kit on sale right now, Lol. I had no idea. Ended up putting a new old style R12 compressor (w/fittings) it was $30 cheaper than the new 134a compressor. Same part, different head, kept my same hoses and o rings. It worked great. The key is the oil. Its compatible with both refrigerants. They claim mixing the original oils plugs things up. Here’s the exact kit. 25 years later. It has everything you need along with instructions.

 

I don't know where you'd buy r12. It was discontinued in 99.

You might find some on ebay but it's probably all air by now. There's 3rd world stuff. But it's flammable.

In the beginning. A complete conversion was needed as 134 wasn't compatible with the hoses and seals. It also ran at higher pressure and therefore a new compressor was needed.

These days it only runs slightly higher then 12. I think the kits these days only contain fitting adapters. But manufacturers had different fittings in the r12 days. Most had the same as gm and Chrysler. Ford had it's own fittings.

As for buying 30 lbs for $87. My last cylinder was about $200 a few years back. Don't know what the price is these days.

You also need a certificate to buy quantities over 2 lbs. Unless you have a connection.