Automotive Air Conditioning Information Forum

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

It looks like an aftermarket under dash unit.

Have to know which refrigerant you are using. Maker of unit? Is there a sight glass on the drier?

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.

Any idea how I would find out who made this unit?

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.

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.