I've got a 63 cadillac and I'm trying to make the factory AC blow nice and cold. I've replaced every component with new - evaporator, rubber lines, all the o-rings, parallel flow condenser, new S6 compressor. I'm also using the Vintage Air STV upgrade kit that uses a cycling-clutch switch with the probe wrapped around the upper tube of the evaporator. After having my shop fill it for the 5th time (love chasing leaks) I can still only get it to blow warm. I'm hoping it's just my compressor belt being a little loose - I popped the hood when I got home and saw it dancing around a little bit. Any wisdom from folks who have done similar, before I throw in the towel and go to Vintage Air? I'd like to retain the factory look inside if possible.
You say it's blowing warm. That's the air coming out of the vents, right? What is the temperature of the evaporator, or the suction line coming from it back to the compressor? If the hose is cold, then you have an air distribution problem, such as a bad vacuum door actuator? it's been a long long time, but I remember struggling to get cold air out of a 60 Caddy after getting the refrigeration system working properly.
Tell us what your suction and discharge pressures are reading on your gauges. What is the supply air temperature that you are getting from your dash outlets. What is the ambient temperature where you are. As mentioned above the big line should be cold and the small line should be fairly warm but not really really hot. Fairly warm means you have some subcooling that is, liquid being delivered to the expansion valve. If it feels fairly hot it's probably short of refrigerant. However you pointed out that Your drive belt was struggling to operate your compressor. was it actually just loose or would you say it was struggling and the belt was reasonably tight ? Did you evacuate the system and purge with refrigerant and then evacuate again before charging? But then you said that your shop refilled for the 5th time? And it's still leaking? Don't go back to that shop. Buy yourself an electronic leak detector and find the leak and fix it. I'm ***uming procedures were followed to properly install your system. Without pressures and temperatures everything is a guess. So since we're guessing, I'm going to guess your expansion valve is defective and not opening. Either that or your system went dry by the time you got home and your low pressure switch did not shut down the clutch on your compressor.
I got my dealer fit AC in my 62 Merc working, it uses the single piston York Compressor. It’s icy cold. They’re a really good system. The one thing I’m surprised about is your mention of o-rings, back then AC were usually compression fittings or quite often hose clamps.
Flare fittings were used on really old systems, but also on aftermarket systems well into the 70s or 80s(?) but O rings were being used on OEM stuff by the 60s.
The knee knocker someone put in my 56 Olds was ***embled with hose clamps. It has held a charge for three decades. No ********.
^ Pressure numbers at what ambient temp are needed. Can't give any worthwhile diagnostic tips without any hard numbers.
Here's a link to a video of the belt doing the stanky leg: https://youtube.com/shorts/S2LEvcHr3Ts?feature=share
Replacing the vacuum lines is a start. If it's like my Riviera, it has at least two vacuum diaphragm actuators that open and close to direct fresh air in and to direct hot and cold air to the proper vents, as I recall. The diaphragms of both of mine were toast, so I bought and installed new ones from Old Air. Then you have old hoses, that weren't barrier hoses like is required for R134. It's a challenge.
I am using 134a. Everything has been replaced - however I am using a new, albeit "old-style" expansion valve. This also needs to be investigated. The diaphragms appear new and in good condition. The air HAS blown ice cold in the past before it leaked out. Gauge readings to come.
Can you report your residual pressures and ambient temperature before you start the engine ? Set the temperature as low as you can and fan on high and outside air set to open and the doors open on the car. Then tell us how long it takes for the sample pressure readings to stabilize without doing anything more. If you have a laser handheld thermometer give us the readings of the big pipe and the little pipe. If you don't have one touch them and tell us what you think the temperature of each of those is. A video of your gauge behavior would be best.
WAIT! I just noticed that you are in Austin. So am I. I'll be glad to drop by and take a look at your situation. Send me a private message.
I'm using An old mark 4 under dash AC unit with the old type expansion valve with 134 and it works great
Finally got around to testing it. Why is it always the obvious problems? Ain't got no gas in it. Confirmed via 2 different gauges reading 0/0. Confirmed compressor was receiving power. Using a UV light, the only leaks I found were around the STV valve (including STV delete kit from OldAir). Unfortunately, I couldn't tell what was new and what was from the previous leak. However I'm still suspect because everything else has been replaced. OldAir sold me this kit: https://www.oldairproducts.com/prod...1x0BBCfrIsqOtOQ_OkG9tqDnm1KLgXC1HSMYRYQaBezN_ There's a gasketed block-off plate that goes in the STV housing. This seems to be problematic, like it can't hold the 134a. I wish they sold me this style which eliminates the OEM housing and replaces it with a nice new pipe: https://www.oldairproducts.com/product/50-2503-stv-eliminator-kit Maybe I can talk them in to letting me order just that pipe. Here's a picture of my STV housing: https://imgur.com/a/XHhfOwZ
Did you miss my private message I sent you? Since you haven't responded to my private message I'll just say it here. I'm in Austin and I have a leak detector .. I would be glad to come over and see exactly what's leaking.
In conclusion: big thanks to '49 Ford Coupe for taking time out of his day to come over to mine and help out. If you're chasing a leak, BUY A LEAK DETECTOR - hopefully I've filled mine for the last time. 5&M
On the first p*** with the leak detector we found that the o-ring fitting on the entering side of the expansion valve at a small leak, and alarmingly I got it indication of evaporator leak when I tested on the outlet grill inside the car. But later after evacuating and purging and recharging we could not duplicate that reading. However, It may take a while for the evaporator leak to be indicated at the grill.
The Jalopy Journal
