?'s about getting A/C Working on 75 Duster

[shanker]

Now that my wife and I have a kiddo...the A/C is important

I'm trying to get the A/C working on my wife's car which is a 75 Duster 360

I was told by her FIL, that before the engine was pulled for an overhaul, the A/C worked (when she was 16, she's now 32). I recently had the lines redone (using new barrier line), I got a new drier and new Expansion Valve, and got the electronics on the inside working (needed a blower motor switch).

What do I do about the compressor? I jumped the pressure switch and it turned over and sounded like an air pump should (I only did this for a second to verify that the clutch worked and compressor didnt have a nasty knock), but I was warned by my FIL, that the RV2 compressor is known to leak.

I plan on going back with R12 (for efficiency) and want to make the A/C nice and ice cold again in the cabin .

What do ya'll think I should do with the Compressor? about every other component in the system is either refurb'd or new, but a compressor is a big chunk of change...

 

[RedFish]

Sad that I just threw a perfectly good RV2 away. Someone will have a good used one.
Post in parts wanted Good luck

 

[BWDart]

R 12 is really expensive if you can get it, some parts places do carry freeze 12 which is a supstitute, you might want to convert

 

[slantsixdan]

Your car would originally have had a V2 compressor (9.45 cubic inch displacement), not an RV2 (10.5 cubic inch).

Those compressors are not "known to leak". Some other compressor designs such as the GM R4 are known to leak, but not the V2/RV2. If you have the system open and empty, it's an opportune time to install a new shaft seal as a sensible precaution against leaks, but other than that, if it's in sound shape (and they usually are; they're very durable), go ahead and run with it. It's a common misconception that axial compressors (e.g. the Sanden, Seltec, or Nippondenso) are "more efficient" than the reciprocating V2. They're lighter weight, for sure, but internal friction in the axial compressors is much higher than in the V2 due to the greater piston/cylinder total surface area (5 or 6 or 7 pistons instead of 2) and the losses due to the swash plate. The V2 requires lower overall torque for a given head pressure, though its torque profile is very "peaky" (torque input required spikes sharply as each piston hits its compression stroke), so the mount brackets have to be set up correctly and belt setup and tension are more crucial than with an axial compressor. I like to use the clutch assemblies with an inertia ring (flywheel) built in; they smooth out the torque peaks.

Do make sure the EPR valve is working correctly. It's located in the rear (low side) port of the compressor. Once the system is charged up, you can follow service manual procedures to put an eye on it and see how it's doing. Or you can replace it on speculation if you like. They haven't given me much problem over the years.

R12 or R134a are the only refrigerants you should use. Do not use the hydrocarbon-based "replacement" or "substitute" refrigerants (OZ-12, HC-12, RedTek, etc.). They work, but they're dangerous and illegal. Do not use the non-hydrocarbon "replacement" or "drop-in" refrigerants, either (Freeze-12, etc.). They work poorly and cause problems. R12 really isn't expensive; there's not much demand for it any more and your system really doesn't need that much of it. Go look on eBay and see the steady parade of NOS R12 cans!

The best upgrade you can make is a parallel-flow condenser. This will make an enormous improvement in the efficiency and performance of your system regardless of which compressor and what refrigerant you use. Lower head pressure (and therefore lower torque load on the engine from the compressor) due to lower flow restriction.

Reference: parallel-flow condensers
and comparative refrigerant tests under standardized conditions -- look at the difference in performance between a serpentine condenser like you have now, and a parallel condenser...with ANY refrigerant.

The other big upgrade has nothing to do with the workings of the A/C system itself: insulate the car! Find and seal all the holes in the firewall and floor pan, take down the headliner and put insulation up there before reinstalling the headliner, insulate the door panels, and put some quality tint (Llumar, for example, not the cheesy dark purple junk) on all the glass. This will dramatically reduce the "solar oven" effect that defeats even the best-working A/C system.

 

[Skeeter]

You'll need to buddy up to a tech or get access to gauges and a vacuum pump. Pull a vacuum on the system to make shure there are no leaks (pull it down valve it off and see if it looses vacuum). If that checks out buy a 134a conversion kit (134a,oil,filler adapter) and gas it upwith the oil (shake the small can to get oil and refrigerant in). After you get some in, start the car and turn the AC on full. If the pressure switch is made the pump will pull in the mixture on its own. The conversion kits gauge has color zones on the dial to tell you when the pressure is right. Fill it up to the green zone and let it run for a while. Put the gauge back on and check it. Good to go. Check with your conversion gage periodically to make sure it good. 12 and 134a use different oils but since you had it apart it should be gone. Seals could be an issue down the road, and you will loose some capacity on the unit. Sorry thats as short as i can make it hope that helps.

 

[shanker]

thanks for the tips, I'm going to be using R12 for sure (as I've already got it).

Whats the story on these parallel flow condensers? Can I get one that's bolt-in and will match up to the factory lines?

 

[slantsixdan]

Whats the story on these parallel flow condensers?

Um…didn't I already tell it?

(using R12 is a fine choice. Using R134a is a fine choice. Using an "R134a conversion kit" from the parts store is an unwise move unless you are trying to kill your compressor.)

 

[shanker]

Um…didn't I already tell it?

(using R12 is a fine choice. Using R134a is a fine choice. Using an "R134a conversion kit" from the parts store is an unwise move unless you are trying to kill your compressor.)

yes you did...but no link to say whether or not there are parallel flow replacement condensers for our A-Bodies

 

[slantsixdan]

There's no exact direct-fit item, no -- you buy the one that has the right dimensions for the cutout in your radiator support, mount it, then you'll need some hookup work (should be easy with standard elbow fittings readily available to/from anyone who makes A/C hoses).