I've got A/C again! At least for now. I can't recall for sure if any of it actually worked or not when I bought it, but for sure none of it worked a week ago. I was just going to buy some cans of 134a, an R12 conversion kit, and wing it, but since I didn't have a real clue as to how the dual ambo system worked I figured I should go bit bigger. I went to autozone and bought a fairly decent set of hoses and gauges, cans of fill, the adapter kit, a UV light to check for leaks, and a bunch of replacement o-rings. Next stop was the local Harbor Freight to pick up the vacuum pump everybody uses, and I was pretty much set with everything I figured I'd need to do a first class job of totally screwing up my A/C system.
First thing to do was get the gauges and hoses assembled, and then see about installing the conversion kit. Good News Everyone! The conversion to 134a had already been done at some point so I was ahead of the game there.
Here the gauges are already hooked up and I'm actually at the tail end of everything, but you can pretend I'm at the beginning. First thing I did after getting plugged in to the high and low side was pull vacuum for about 45 minutes, shut it down, and close it all off so I could do a leak down test. For about 30 seconds or so after turning on the pump I could see vapor from the moisture in the system boiling off. It didn't last long so I don't think there was much in there. I let it sit for about another 45 minutes and the gauges didn't budge, which surprised the snot out of me. I thought for sure I'd be chasing down leaks someplace. I'm not entirely sure why the system was empty. I know there was at least a bit of residual pressure in there because when I plugged in and cracked the valves I could hear air hissing out. According to what I read this was a good sign that everything was still sealed.
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Here's the vacuum pump I used. I think it cost me around $80 after using one of their 20% coupons. I can't really imagine needing this for anything else, but what the heck, can't hurt to have another tool in the shed. It wasn't as loud as I figured it would be, and didn't vibrate at all. I have a small compressor like this and that bugger vibrates like crazy. I kind of figured a vacuum pump is just a compressor in reverse and expected similar performance.
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Here's a shot of the lines hooked up. The high pressure side was obviously easy. The low pressure side that disappears back there into the darkness was not nearly so easy. I had to do it by feel one handed, and there were some other kinds of lines and hoses back in there that were really interfering with getting the connector on. The one handed part was what made it so difficult.
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I'm going from memory now but as I recall I put in 1 3oz can of oil, I -12oz can 134a w/UV additive, and 1 -14oz can of 134a, for a total of 29oz. Ambient temperature was about 73 deg. With the A/C in the cab running and the thermostat on the box system set at about 60 degs. my low side pressure was running at 44 psi and the high side was just shy of 200 psi.
Now if I shut down the system in the box, my low side drops about 5 psi and the high side drops about 15 psi. Since this post pretty much contains the sum-total of my knowledge of A/C systems, I have no idea why this is. The temps I'm getting at outlets are about 50 degs. I'm not sure how accurate this is since I couldn't find a proper thermometer and was using one of those handheld infrared temp checkers. I use these at my shop for spot checking the temp of the parts we're repairing, but since those run anywhere from 700-900 degrees, a 5 or 10 deg variation is negligible. I'm not sure these handheld units are that incredibly accurate at these low temps, but I will say that although it blows way colder than it did last week, my tried and true "palm in front of the vent" test didn't make me go "daaayum, colder than a witches tit".
I have no idea what it would have cost me at an A/C shop to get to this point. I did a leak down test, did a UV leak test, added about 29oz of fill, and spent about $200 or so on the pump, gauges, an adapter for hooking up the 134a cans to the system, and the handheld UV light.
Hopefully this is going to hold and I'm done with the A/C for now. I'm slowly chasing down and getting rid of the "little things" that seem to plague units of this age. Windshield leak, dash lights gone, MIA cruise control, non-functioning idle control, etc etc. All those have been taken care of. The last "major" little thing I need to address is the leaking power steering pump. I'm not 100% certain but I think the pump housing itself has a crack or puncture or something on it's side about halfway down from the top. It will leak to a point and then stop leaking. If I add more fluid it starts leaking again.
A potentially major thing I might be staring at is a transmission issue. It has this intermittent thing where the torque converter seems to be locking/unlocking erratically. I've read, and I hope it's my case, that there is a somewhat problematic electrical connector on the tranny pan that can cause all kinds of funkiness if it isn't up to par. I'm hoping if I sacrifice a young virgin chicken to the Mercon god I might get lucky. I pretty much figured on a tranny rebuild when I convert with ujoints 4x4 kit, but I wanted to be able to do it when "I" was ready, not when it decided to go south on me. Crossing my fingers.
