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R-12 auto A/C tech in chit chat

plym49.2 said:
I would normally do low side/liquid/motor running and a bit at a time.
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that's what I do

on your 'low vacuum' woes, the compressor might be leaking already, might wanna charge it with something cheap before you dump expensive 12 into it
those r4 compressors really like leaking where the shell wraps around the compressor body
 
Thinking of adding UV dye and leak stop with an ounce of oil to make up for a little that came out the loose fitting. At the same time as I am filling it up.
 
[486] said:
that's what I do

on your 'low vacuum' woes, the compressor might be leaking already, might wanna charge it with something cheap before you dump expensive 12 into it
those r4 compressors really like leaking where the shell wraps around the compressor body
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Meh, it's a new HF vacuum pump that someone gave me. I'm sure it's good enough. Also, my cheapo gauges might not be accurate. And it is a new rebuilt compressor.

I should have converted to a Sanden.

BTW the system did hold that vacuum for over an hour before I disconnected everything.
 
plym49.2 said:
Some forward progress today.

I noticed that one of the fittings on the condensor (the high pressure line) was not tightened

Do green o-rings work with R12/mineral oil?
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Yes. They work with anything but brake fluid.
 
[486] said:
poe (ester) oil is fine with 134, too
probably just an orifice tube

whatever, run what you brung and all that
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Not a lot of information on Japanese market rover air conditioning.
Jam some 152 in it, get cold air, be done.
 
Replaced the pressure switch (o-ring looked a little fugazy), mixed a cocktail of UV dye, stop leak, and mineral oil, pumped it down (still 24-25" - and still held it), and slowly added just under 2.5 lbs of refrigerant.

It is cooling. Return to the compressor is nice and cold.

Tomorrow have to reinstall the plastic housing around the evaporator and related duct work.

Thanks for all of the advice! Will let y'all know if it holds up.
 
Road trip over 1600 miles. Blew ice cold.

Never had time to reinstall the underdash enclosure panels around the evaporator and heater core. Omitted the heater core and blew air through the open evaporator kinda sorta like a window unit. A couple of USB fans to blow the cold air up and over. Rigged a mud pan with a drain to catch the condensate.

Worked fine - froze my butt off at times.

Thanks for all of your help, support, advice, and ball-busting. Still a little work to do but she works. :)
 
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Seals with p/n for future reference.
 
71PA_Highboy said:
Now get the rest of the enclosure put on so Colt doesn't freeze in the footwell.
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I hit an odd overheating problem on the way back. Engine was sometimes running hotter than it should for no apparent reason.

Then I had an idea. There is no heater core in it yet since it mounts to the enclosure. I bypassed the heater with hose direct from A to B. I thought 'what if the system wants to see the restriction of a heater core? maybe too much coolant is bypassing?'. I closed the valve on the rear of the manifold and the issue cleared up. Not sure I understand why as the hot water from the rear of the intake dumps right back into the top of the rad.
 
plym49.2 said:
I hit an odd overheating problem on the way back. Engine was sometimes running hotter than it should for no apparent reason.

Then I had an idea. There is no heater core in it yet since it mounts to the enclosure. I bypassed the heater with hose direct from A to B. I thought 'what if the system wants to see the restriction of a heater core? maybe too much coolant is bypassing?'. I closed the valve on the rear of the manifold and the issue cleared up. Not sure I understand why as the hot water from the rear of the intake dumps right back into the top of the rad.
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Back in the day, before thermostats like we have today they used to have, or you can make, different size washers to put in the return line to the radiator.

This would slow the flow enough that the antifreeze had time to cool down in the radiator before it was sucked back into the engine.

So if you had an engine running to hot. You try a washer with a smaller hole. If it gets hotter than you use a washer with a bigger hole. That type of thing.
Hole gets too big then the engine runs too hot, hole gets too small then the engine runs too hot. LOL It took some common sense.

But that was back when men were men and could actually read and understand and had a real temp gauge.
 
plym49.2 said:
I hit an odd overheating problem on the way back. Engine was sometimes running hotter than it should for no apparent reason.

Then I had an idea. There is no heater core in it yet since it mounts to the enclosure. I bypassed the heater with hose direct from A to B. I thought 'what if the system wants to see the restriction of a heater core? maybe too much coolant is bypassing?'. I closed the valve on the rear of the manifold and the issue cleared up. Not sure I understand why as the hot water from the rear of the intake dumps right back into the top of the rad.
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gen 1 SBC has really retarded water jacket routing
the water pump circulates everything through the rad and nothing through the engine, until the tstat is in there and closed, then it circulates through the engine.

this resulted in a whole generation with a disastrously wrong understanding of heat transfer
(faster flow transfers heat better as it strips boundary layers away, and you dump more heat outta the rad if the coolant's moving fast enough that the inlet and outlet are nearly the same temperature since if it is coming out colder, some portion of the fins are colder and therefore doing less heat transfer to the air)
 
[486] said:
gen 1 SBC has really retarded water jacket routing
the water pump circulates everything through the rad and nothing through the engine, until the tstat is in there and closed, then it circulates through the engine.

this resulted in a whole generation with a disastrously wrong understanding of heat transfer
(faster flow transfers heat better as it strips boundary layers away, and you dump more heat outta the rad if the coolant's moving fast enough that the inlet and outlet are nearly the same temperature since if it is coming out colder, some portion of the fins are colder and therefore doing less heat transfer to the air)
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Starting to make sense. So I would have been better off blocking the heater core circuit (as it is now with the valve closed) than running the bypass line. With the bypass, not as much flow because smaller ID. (???)

But if the motor was hot enough (as much as 230 degrees with a known good 180 'stat) for the 'stat to be open and the bypass line is there as well, wouldn't that be better? Or did that dump too much coolant into the rad for the coolant to flow quickly enough to cool as describer?
 
plym49.2 said:
But if the motor was hot enough (as much as 230 degrees with a known good 180 'stat) for the 'stat to be open and the bypass line is there as well, wouldn't that be better?
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Nope, the heater core is plumbed same as the radiator, with flow preference as compared to the engine.
Once the tstat opens then it's even more flow that doesn't go through to the back of the engine.
You do need some bypass flow though, in order to circulate coolant past the bottom of the tstat so that it opens. If yours has a separate bypass hose on it it'll usually have a restricted fitting with about a 1/2" hole through it.
 
[486] said:
Nope, the heater core is plumbed same as the radiator, with flow preference as compared to the engine.
Once the tstat opens then it's even more flow that doesn't go through to the back of the engine.
You do need some bypass flow though, in order to circulate coolant past the bottom of the tstat so that it opens. If yours has a separate bypass hose on it it'll usually have a restricted fitting with about a 1/2" hole through it.
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No bypass hose on this (350 TBI). Hot water out of the right rear of the intake and returns right into the rad by the upper hose.
 
I’ve got around 12 lbs of R-12 in a 30lb container if anyone needs it . Bought at an auction recently by mistake listed as R-22.
 
Man, I couldn't be happier with this thread. I've been needing to recharge the ac on my r12 rv system. 38ft of line (x2) plus condenser, compressor, and dryer. 24 ounces filled it up.
20240710_195756.jpg
pressure/temp chart for r134a was 45-55 low and 250-270 high for full charge. 60% is 35 and 165. Its right there.
20240710_195806.jpg
and blowing 13 degrees out of the vent at 95 degrees ambient. Absolutely stoked to get the dash air working on my pusher.At 4 bucks a can you just can't beat it.
20240710_195706.jpg
 
1Sinner said:
Man, I couldn't be happier with this thread. I've been needing to recharge the ac on my r12 rv system. 38ft of line (x2) plus condenser, compressor, and dryer. 24 ounces filled it up.
20240710_195756.jpg
pressure/temp chart for r134a was 45-55 low and 250-270 high for full charge. 60% is 35 and 165. Its right there.
20240710_195806.jpg
and blowing 13 degrees out of the vent at 95 degrees ambient. Absolutely stoked to get the dash air working on my pusher.At 4 bucks a can you just can't beat it.
20240710_195706.jpg
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R152A?

Be careful. You will likely ice up your evaporator at such low temperatures.
 
it says F
and 24oz in an old generic upfitter system with 40 ft of lineset is waaaay light on the charge, it probably had like 5lbs of r12 in it

low charge makes extra cold (but low capacity), since the low side goes into vacuum
 
No weight anywhere on the system. I was worried about icing, but happy with the results. I'd rather be undercharged than over charged. But willing to entertain adding another can. But pressures should have been correct based on the 60% rule.
 
1Sinner said:
No weight anywhere on the system. I was worried about icing, but happy with the results. I'd rather be undercharged than over charged. But willing to entertain adding another can. But pressures should have been correct based on the 60% rule.
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clutch cycling fast?
 
According to this, 30PSI low side in R152A should be about 40F, quite adequate for A/C.


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