Automotive Air Conditioning Information Forum

I have a 73 Nova where previous owner had everything replaced and went with r12 7 years ago. Noticed that the POA valve looks "exactly" like the upgraded ones (eliminator). It has 4 ports just like they do however where the switch usually mounts its just capped off. The compressor is a newer clutch style compressor if that matters. Can one of the upgraded POA valves be used on r12 and if so since my compressor is a newer r134a style (ACDelco 4849) should I have a cut off switch wired in to be more efficient? HAha it took the pic when it edit mode...go figure!

as far as posting a pic, it should be easy.
I would be sure the file format is .jpg
The site may have trouble with other file types.

Evidently apple has a new pic file format (namely HEIF and HEVC) that is not compatible with anything, a guy on another forum couldn't make it work until we told him to switch back to the tried and true .jpg format.

That is a piece of pipe. Sold as an upgrade for a precision control valve.

Depending on what compressor you have it may or may not turn the evaporator in to a block of ice on a long drive.

Your compressor number comes up as a fan clutch for me. Which compressor do you have?

bohica2xo wrote: ↑Sun Jul 18, 2021 4:18 pm That is a piece of pipe. Sold as an upgrade for a precision control valve.

Depending on what compressor you have it may or may not turn the evaporator in to a block of ice on a long drive.

Your compressor number comes up as a fan clutch for me. Which compressor do you have?

its a ACDelco 4849 here is a pic of it.

That is an R4. The actual part numbers are in the top part of the picture.

You can run that compressor without a POA valve, but you will need either an evaporator temperature sensor or a cycling switch on the low side.

Not clear where the TXV sensing bulb is located in that picture. Hopefully it is clamped to the evaporator discharge line and insulated.

With an R4 running 100% of the time you will push the evaporator well below freezing if the rest of the system is working properly.

bohica2xo wrote: ↑Sun Jul 18, 2021 4:56 pm That is an R4. The actual part numbers are in the top part of the picture.

You can run that compressor without a POA valve, but you will need either an evaporator temperature sensor or a cycling switch on the low side.

Not clear where the TXV sensing bulb is located in that picture. Hopefully it is clamped to the evaporator discharge line and insulated.

With an R4 running 100% of the time you will push the evaporator well below freezing if the rest of the system is working properly.

Thanks for the info.I have not seen a temp sensor and of course no cycling switch on the POA....should I install a cycling switch on the POA and set it around 25psi (or is it 30 psi for r12)? The compressor is cycling on and off but more off than on. Almost forgot it does have a clutch cycling thermostatic switch

The TXV bulb I'm hoping is clamped to the evap discharge line as its inside the box and sealed up with the black tape sealer stuff.

As far as freezing ...well the temps isn't all that cold was getting ready to look into but figured I would find out what exactly I have as the POA was confusing me....again thanks for your reply!

tbirdtbird wrote: ↑Sun Jul 18, 2021 3:05 pm as far as posting a pic, it should be easy.
I would be sure the file format is .jpg
The site may have trouble with other file types.

Evidently apple has a new pic file format (namely HEIF and HEVC) that is not compatible with anything, a guy on another forum couldn't make it work until we told him to switch back to the tried and true .jpg format.

Many miss that all you have to do to post a pic. is click the attachments tab. Add file and select Place line.

Yep. If you have never been on a forum posting pix doesn't necessarily come naturally
He said he got an error message that there was a compatibility issue

So I have a updated POA and using a clutch cycling thermostatic switch in place of the electrical switch that is usually mounted on the POA. Now that I know what I have guess its about time to start troubleshooting. Now I wonder since I already have most things in place for it if I just convert to r12?

EDIT *SORRY, I meant to change it to r134a.*

I would just stay with 134a in that hybrid system