Vintage Air SureFit Condenser Kit 21567, for 1967-72 C10 and C20 Chevy & GMC Trucks
 

I installed a Vintage Air SureFit Condenser Kit in my '71 Chevy C20 pickup.
https://vintageair.com/1967-72-chevr...r-kit-w-drier/
It fits all the original holes in the radiator core support and the lines screw into the OE liquid and vapor lines. The parallel flow condenser does a good job of keeping head pressures low even when the truck is sitting still at an idle. Decent upgrade in my opinion.

This video, https://www.youtube.com/watch?v=Z0_4IpBTlAk, shows how to vacuum and charge the system with R134a. Because the new condenser and drier are of smaller volume, the recharge only took about 26oz of R134a. That is two 12oz cans and just a tiny amount from a 3rd can. Pressures once stabilized were 26-28 psi on the low and about 250 psi on the high with ambient temps of 94-95F. Outlet temps were blowing about 58-60F. I was hoping for colder, but I've not checked my HVAC blend door to see if it opening/closing correctly.

Note that before charging I adjusted the POA valve relief pressure to 26 psi. This puts the evaporator temperature at 2 degrees below freezing. I'm hoping it doesn't develop ice on the evaporator coil. So far, so good. Probably would freeze up if I run the a/c in cooler temperatures, for instance when using defog.

Re: Vintage Air SureFit Condenser Kit 21567, for 1967-72 C10 and C20 Chevy & GMC Truc
 

It will develop ice with the defrost... but turning the heater on for a min or two should thaw out any ice build up. That's what commercial walking freezers and refrigerators do..
You're probably right about running it in cooler temps.

Re: Vintage Air SureFit Condenser Kit 21567, for 1967-72 C10 and C20 Chevy & GMC Truc
 

Will see...

A little disappointed in the outlet temps. I checked my temperature and direction HVAC doors and everything seems to be working. I'd guess the gaskets are toast after 53 years. So probably some leaks on the air intake and exhaust. Service manual says a 4 season GM system should get 40's Fahrenheit at 90-100f. Something isn't quite right.

I can say the condenser is working well at keeping pressures low. The evaporator is putting off a lot of condensation. That cold just isn't making it efficiently to the cabin. Leaks, right?

Re: Vintage Air SureFit Condenser Kit 21567, for 1967-72 C10 and C20 Chevy & GMC Truc
 

Low side sounds really low. I would expect 45-55 or so. Was that at idle or a higher RPM, and did you have a big-a$$ box fan blowing at the condenser?

My only A/C experiences have been with complete V/A systems, and just today a 99 Chevy pickup. At around 85 deg ambient at 2,000 RPM we got it blowing 45 at the center vent, and, as I recall, pressures were 45-55psi and 150-160psi.

I assume you pulled a vacuum on the system before charging, right?

Re: Vintage Air SureFit Condenser Kit 21567, for 1967-72 C10 and C20 Chevy & GMC Truc
 

Insufficient airflow across the the condenser will cause low suction pressure and higher head pressure. Why would you set POA under freezing? Should be at around 27.5 PSI. The stock mounting with condenser spaced away from radiator is not good for airflow unless driving at speed. Mount against rad, construct a shroud or add an auxiliary fan to improve performance at stops or low speeds.

Re: Vintage Air SureFit Condenser Kit 21567, for 1967-72 C10 and C20 Chevy & GMC Truc
 

As I recall, these trucks recirculate air through the kick panel vent and the air travels through the cowl. I followed the path and that sends the air through the outside of the vehicle and has the potential to warm the air. There is a cowl vacuum activated door that must be in working condition for recirculation to work. That being said, this path has always worked and guys on here say it should not matter and a good working system should freeze you out anyway. I went ahead and created a path that does not go outside for recirculation. I have not tested it yet. Another thing is that you might want temporarily disable your heater to see if there is heat affecting your cool air. I live in Florida so the heater is seldom used. Most newer cars have the condenser right up against the radiator and electric fans. I may have missed it but what compressor are you using and is it new?