1971 Chevy pickup

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72gmc4x4
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1971 Chevy pickup

Post by 72gmc4x4 »

How do I find out how much refrigerant is needed in my system?

It looks like an aftermarket under dash unit.
Dougflas
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Re: 1971 Chevy pickup

Post by Dougflas »

Have to know which refrigerant you are using. Maker of unit? Is there a sight glass on the drier?
72gmc4x4
Posts: 41
Joined: Wed May 04, 2016 11:19 pm

Re: 1971 Chevy pickup

Post by 72gmc4x4 »

Thank you for your reply. I've had a hard time finding the name of the forum which is why I've taken so long to get back to you.

I still don't know if I should use r12 or r134a. I'm in Phoenix and this saturday is expected to be 118*. I want whatever is going to work best in my beast.

One thing I did find out is that the compressor is an sd508. I have to double check. My pops is driving the truck for the next few days.
72gmc4x4
Posts: 41
Joined: Wed May 04, 2016 11:19 pm

Re: 1971 Chevy pickup

Post by 72gmc4x4 »

Any idea how I would find out who made this unit?
72gmc4x4
Posts: 41
Joined: Wed May 04, 2016 11:19 pm

Re: 1971 Chevy pickup

Post by 72gmc4x4 »

Would you recommend staying r12 or going to r134a. I have 2-12 oz cans of r12 but I don't thinks it's enough for this system.

A mechanic friend advised r134a because of cost and he also said that with r134a, the outcome will be the same if done correctly. I just need to add an electric fan to increase airflow on the condenser at lower speed.

There is a sight glass on th drier.
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Jsmitty
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Re: 1971 Chevy pickup

Post by Jsmitty »

Stick with R12. Those under dash systems blow ice cubes when everything is right.

I had one in my '72 El Camino when I lived in Phoenix - it was great! I ran Freeze 12 (80% 134a) in mine using a larger, parallel-flow condenser.
Finally got ahold of some R12 many years later back in the Northeast - the difference was very noticeable. It would fog the back glass up.

The name of the unit should be on the under-dash evaporator case somewhere. If you look real close, you can see mine was an AMA unit.

If I remember right, I think mine was around 36 oz. or so, maybe less (this was Freeze-12, so YMMV). I would just charge until the unit starts cooling well, using that amount as a guideline.

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