DPD air conditioning questions, service ports? dropping engine? Options

[iankarr]

Hi Guys,

My '74 came with the DPD A/C unit and it appears that the PO has already updated the compressor. I'm trying to determine the charge status and the service ports aren't anywhere obvious. Could they be the bolt-looking things on the compressor in the pic below? Are they hiding under the conical cover?

Also...

When dropping the motor, do most people unbolt the compressor from the engine? Or have the system evacuated and unhook the hoses?

Not even sure I'll use the A/C...but it's in great condition, so I figured it might as well work.

Thanks!

[jcd914]

Yes those are the services ports on top of the compressor.

There are caps that screw on over the port to keep the clean and protect the valve inside.

The receiver/drier should have a sight glass on it that you can use to tell if you are low on Freon.

It is normal to unbolt the compressor from the engine to avoid the cost of discharging and recharging the AC.

Unless it has been upgraded to R134A, it will have R12 in it and most states (maybe all) require certified/licenses technicians only service the system and require a recovery system to capture all the old Freon.

Jim

[72hardtop]

Yes those are the services ports on top of the compressor.

There are caps that screw on over the port to keep the clean and protect the valve inside.

The receiver/drier should have a sight glass on it that you can use to tell if you are low on Freon.

It is normal to unbolt the compressor from the engine to avoid the cost of discharging and recharging the AC.

Unless it has been upgraded to R134A, it will have R12 in it and most states (maybe all) require certified/licenses technicians only service the system and require a recovery system to capture all the old Freon.

Jim

Sanden compressor

[iankarr]

Thanks. Any way to tell if that compressor is a R134 unit? Or could it also be freon?

[ejm]

Hoses for freon screw onto external threads on the fitting. R-134 fittings are quick release like air hose fittings. Older compressors can be adapted to R-134 with a special fitting that should have been left installed. Updating refrigerant also requires changing the oil in the system. New R-134 systems don't have a sight glass since it's useless to determine charge level but one may be found in updated installs.

[Amphicar770]

As noted, R134 are quick connect. Those look like R12 caps.

You do not need to drop engine to service the AC. I redid my entire AC system with engine in car. When you do drop engine you likely need to unbolt the compressor just for clearance when lowering engine.

If you are going to restore the AC you may as well do it right (especially if you are going to convert to R134). Replace all the hoses with modern barrier hose, drop the AC unit inside the car so you can do those hoses as well and a new expansion valve. Flush the evaporator and condenser then use lots of dry air and ideally nitrogen. Change the oil to appropriate type. You certainly want a new receiver drier.

I did all this about two years ago and will say that the AC will freeze you quickly and the rotary compressor does not rob power like the old York. I kept mine R12 but I have a bunch of it stockpiled and the equipment / certification to deal with it.