Tips on Recharging A/C

[k2choi]

Does anyone have instructions on how to charge freon? My car is a 00' C2 cab. A/c blows warm to cool [moist] air. Compressor clicks on, so I suspect charging freon may be first thing to do. Any other diagnostic tips would also be appreciated.

I've searched forums and wasn't able to come up with anything. Many thanks in advance.

[peter-pa31]

I am far from an expert, but I have charged some auto A/Cs recently. I think an expert would tell you that the only truly correct way to charge the system is to have a set of gages that will give you both the high and low pressure sides of the system simultaneously. These numbers can be compared with the specs for your system and the appropriate charge can be applied.

In practice, I have found that the cheap (~$20) low pressure side gages that are sold at most auto supply stores are good enough to get a reasonable charge. The gages that I have seen are usually marked in both PSI as well as yellow/green/red arcs. The goal is to charge the system from the low pressure side while the compressor is running and have the gage read somewhere in the green arc. One of the obvious drawbacks of this is that you can not read the charge while adding refrigerant, so you need to add it in small increments and then check the pressure. Note that the pressure reading is only meaningful if the compressor is running.

[wwest]

WAIT, STOP!

There is a low pressure cutout switch that if the "freon" is too low the compressor clutch is disabled.

Have you tried "max cooling"??

If you run the temperature setting to max cooling then the system ignores all the sensors and closes the reheat/remix path. If this works then you may have an open cabin atmosphere temperature sensor which would falsely indicate the cabin as COLD.

If it, the above, doesn't work then you may have a failed remix/reheat servomotor that's stuck in a position that causes a large portion of the system airflow to be reheated via flowing through the heater core.

[k2choi]

WAIT, STOP!

There is a low pressure cutout switch that if the "freon" is too low the compressor clutch is disabled.

Have you tried "max cooling"??

If you run the temperature setting to max cooling then the system ignores all the sensors and closes the reheat/remix path. If this works then you may have an open cabin atmosphere temperature sensor which would falsely indicate the cabin as COLD.

If it, the above, doesn't work then you may have a failed remix/reheat servomotor that's stuck in a position that causes a large portion of the system airflow to be reheated via flowing through the heater core.

<{POST_SNAPBACK}>

Thanks for the tip. I tried the max cooling method ['LO setting"] and only got warm-cool air from vents. How can I diagnose possible failed servo motor?

[djantlive]

I think you should go to a pro. They can detect leak and add the right amount of R134. Get recommendation on a AC specialist from a dealer. R134 isn't too expensive but you want to find out why your freon is low.

Also, run the AC once a week or so to keep the seals lubricated. It tends the life.