AC question

[r8rs4lf]

1972 Factory AC truck/ NO heat hooked up
Sticker says 134 on compressor

Since I purchased the truck the AC was never really cold. PO said it worked and even added a switch controlled fan to the condenser, but the switch was broken when purchased which he advised me of. Replaced the switch with no results. I had issues with the fan switch as well that I got sorted out.

I went ahead and purchased a low side gauge and a bottle of 134 in case it needed a charge.

Screwed the bottle on the gauge (closed) assembly and hooked up to the low side (blue cap) of the AC. Turned truck on with AC on and fan on high. As I suspected the system was way overcharged. Went ahead and released some, needle moved, but now seems stuck a tad on the yellow just after green. I can get pressure settings later if needed. As I keep capturing the 134, the needle does not move anymore. Should I keep releasing more until I get the needle in the green area? I feel like I have released a significant amount already although when I look in the window of the drier, I still see refrigerant circling.

Not a pro by any stretch, just wanted to see if it could be something simple before taking it to a professional.

All 3 levers are pushed to the left. Like I said there is no heat hooked up as the lines under the hood were cut. I feel a significant amount of air being directed through the vents, just not cold.

Any help?

[Sheepdip]

You need to have a pro put some gauges on it.

[Steeveedee]

Do you know if the POA valve has been calibrated for 134?

Does the receiver/dryer appear new? It could be the old one.

You won't necessarily see proper action even with an electric fan moving the air through the radiator and condenser. If you have a thermometer that will fit in the center AC outlet, take the truck for a drive and see what the temp drops to when you're going at least 35 MPH.

[mrein3]

Two things need to be done for R134a to work in these old trucks. #1 you need to adjust the POA. #2, the condenser was made for R12 which is much more efficient then R134a. If your pressure is ok but you aren't moving, you might not be pulling enough heat out of the refrigerant. Before you capture any more, take it for a spin and see if the air moving through the radiator/condenser cools it down any.

[r8rs4lf]

All parts of the AC system look to be new(er). I don't have a reason to not believe what the PO told me, but I don't know for sure.

Can I adjust the POA myself?

[weq92f]

.

You're going to need a real manifold gauge set attached to both low and high ports in order to diagnose correctly. My advice would be completely empty the system, pull hard vacuum and then charge the system with the appropriate amount of 134a (based first on conversion charts for your OEM R12 system and secondarily on the pressure readings and ambient temperature).

DIY is possible with the AutoZone loan a tool program:

You cost to "borrow" the tools is zero...

$130: gauge set (manifold)
$200: Vacuum pump

To take the tools from store you have to pay full price + tax.

When you return them, you get refunded full price plus tax so the tools cost you nothing.

Hth,

-Kevin

[Steeveedee]

It has R134 adapters on it, so probably has all R134 in the system. Newer compressor, so probably has the correct oil. You can't rely on the sight glass in the receiver dryer, since R134 has a different boiling point than R12.

Did you try driving it and checking the temperature with the ram air effect?

Make sure of this before you adjust the POA valve (which is possible to do). I haven't done that as I've never converted a system.

[Rufas]

Maybe you might want to consider going back to the R12 Freon. I just purchased seven cans of R12, 14oz, Original GM Freon, for just over $21 a can on Facebook Market place. No adjustment needed to your POA valve. R12 is still available on the internet. But prices seem to be around $70+ a can on these websites. You don't need any AC certificate if you are purchasing 32oz or less. You'll get better cooling if you go back to R12.

I now have a total of 9 cans of R12, enough to last me for years. I last charged my factory system 5 years ago. The system still doesn't need servicing. My POA valve needed replacing, so I used one of those POA valve eliminators designed for R12. I'm not wild about the way the factory air now cycles, but the AC in my truck keeps me cool in Arizona summer temps of 110+ degrees.

Frosty-Freeze Refrigerant States:

Quality Products Since 1979. EPA Certified, Department of Transportation Inspected and Compliant. All the products we sell containing refrigerant, are for EPA Certified Technicians. Purchases for resale do not require any certification; However, you are required to keep accurate records of all purchases made. If you purchase any items from us containing refrigerant, you are affirming one or the other! *Small cans of refrigerant for MVA's, containing 32 oz. or less, "DO NOT" require any certification. Safety Data Sheets listed are for reference purpose only and relate to the ASHRAE "R" number only. All sales are final. We do not accept returns on any refrigerant due to change of possession concerns and hazardous materials shipping requirements. **All products listed are in stock and will ship the same day if ordered by 12:00PM Central Standard Time. If the item is not in stock it will say "sold out".

[leddzepp]

Originally Posted by Rufas

Maybe you might want to consider going back to the R12 Freon. I just purchased seven cans of R12, 14oz, Original GM Freon, for just over $21 a can on Facebook Market place. No adjustment needed to your POA valve. R12 is still available on the internet. But prices seem to be around $70+ a can on these websites. You don't need any AC certificate if you are purchasing 32oz or less. You'll get better cooling if you go back to R12.

I now have a total of 9 cans of R12, enough to last me for years. I last charged my factory system 5 years ago. The system still doesn't need servicing. My POA valve needed replacing, so I used one of those POA valve eliminators designed for R12. I'm not wild about the way the factory air now cycles, but the AC in my truck keeps me cool in Arizona summer temps of 110+ degrees.

Frosty-Freeze Refrigerant States:

Quality Products Since 1979. EPA Certified, Department of Transportation Inspected and Compliant. All the products we sell containing refrigerant, are for EPA Certified Technicians. Purchases for resale do not require any certification; However, you are required to keep accurate records of all purchases made. If you purchase any items from us containing refrigerant, you are affirming one or the other! *Small cans of refrigerant for MVA's, containing 32 oz. or less, "DO NOT" require any certification. Safety Data Sheets listed are for reference purpose only and relate to the ASHRAE "R" number only. All sales are final. We do not accept returns on any refrigerant due to change of possession concerns and hazardous materials shipping requirements. **All products listed are in stock and will ship the same day if ordered by 12:00PM Central Standard Time. If the item is not in stock it will say "sold out".

This ^^^ 100%

[r8rs4lf]

Originally Posted by Steeveedee

It has R134 adapters on it, so probably has all R134 in the system. Newer compressor, so probably has the correct oil. You can't rely on the sight glass in the receiver dryer, since R134 has a different boiling point than R12.

Did you try driving it and checking the temperature with the ram air effect?

Make sure of this before you adjust the POA valve (which is possible to do). I haven't done that as I've never converted a system.

I have driven it to see if it gets cold, but I have not used a thermostat. It does seem to get a bit cold when driving, but aging without a thermostat I cannot confirm for sure.

I got a homie coming to take a look at it. Hopefully it doesn't cost me an arm and a leg.

Not sure if anyone can see, but I'm missing that vacuum valve on the heater part of the firewall. Does not having something like that affect the AC? I would just assume it's to get the AC/heat directed to the correct vents?

Can anyone answer my question as to why the gauge arrow will not drop any further from yellow to green?