Packard Forum Index » Post-War (1946-54)

It could be that there was an outside supplier of those that made them in different configurations. Looking at the 51-54 service manual, they show only the two wires coming from the motor and no heater element. The Parts Manual only list one part number.

I wouldn't wire it up with the front blower as I often use the front blower for forced fresh air, especially in traffic. Total load would be less than 10 amps with the motor and the heater element. Which I will power off of a relay and micro-switch trigger from the "defrost" setting on the dash vent control lever. So basically dash vent lever is in defrost position, it will turn on the rear defroster as well.

I have a gaggle of wiring I need to run from the dash to the trunk to support the A/C setup anyway, so I will run it with those wires. I just need to measure out the distance to calculate the wiring gauges I need at the various AMP loads the defroster will need and the right and left two-speed blower motors. Also the wiring for the thermostat for the compressor clutch.

The plan is to make it so the compressor will only cycle on if at least one of the A/C blowers is running. So that will use a relay and four diodes to accomplish that. Also, the thermostat has to agree, as well as the A/C safety switch, and of course the actual dash A/C switch.

Kev,
For what it's worth, I'll offer to check out the second motor and to lubricate the bearings as well if you end up needing it. The old motors seem to often fail as a result of the wiring where it enters the motor can.

As I said, if you need it. No charge.
Pat

I appreciate the offer. But, the second motor appears to be frozen. It was found in a shed that had an open door, so I think it had a bit of weather exposure to it.

Here is the 56 Novi schematic as used in the custom built unit Novi made for Stude. They didn't use pressure switches and the compressor ran all the time with temp control by a mechanical hot gas bypass valve. Unlike Packards factory trunk unit where temp was electrically adjustable, in the aftermarket trunk units just blowers were electrically controlled.

From the 56 Stude SM, here is a general description of how the unit operates. Obviously yours will be different but between the blower schematic and writeup maybe a starting point for yours. I believe all Studes were 12v in 56 so the wire gauge and fuse data should be good.

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Howard,

Thanks for that. Since I am using a Sanden compressor up front, with new lines, new condenser etc, I will add the safety switch as needed. Probably a trinary switch so I can add a fan later if needed if required. You know how the Calif summers and traffic go together.

I just need to have the evaporator checked for leaks, and then I'll probably replace the old dryer and expansion value with newer ones as I don't know the condition of those. I'll just add a thermostat to the mix which for compressor clutch that will be set to a preset temp. Figure if it gets too cold, then the blowers can be set to low, or just one blower can be left on. Basically, the thermostat is there to keep the evaporator from freezing up.

Is there anyway to test the evaporator for leaks at home? I am sure the most expensive piece in this endeavor is going to be getting those long A/C lines made up.

The rear defroster while probably never used that much except for an early morning car show run here in Calif in the winter months. But it would be useful if I end up relocating to the midwest next year.

Only way I know to test is by pulling a vacuum and closing the evaporator off to see if it holds. In addition to the pump and charging hose setup you would need custom plugs or fittings to connect to the evaporator.

Unless there are signs on the evaporator it could have corroded or some obvious damage it is probably in good condition. They made them a lot more robust in those days compared to the thin metal used today. If it has been open to air then at the least I think I would flush with one of the special flush kits before connecting to any other tubing.

Other than the flush I would just go ahead and hook everything up and let the AC place that does the charging etc do a vacuum test on the system. The fittings would be there and whoever did the charging would probably either have the means of fixing or else be in a position to figure out what modern could replace the evaporator if there was a leak.

I believe the original lines were probably copper but that would be the expensive option today. I did the 47 with ready made lengths of aluminum AC tubing but hoses are easier to work with and rear hose kits are available from several of the aftermarket AC places. IMO, hoses under the car are more subject to damage and heat than metal tubing. I would at the least keep them as far away from exhaust as possible and run them in as protected a location you can find.

The lines are pretty much going to have to run down the passenger side. But I think I can tuck them in the frame rail for most of the length. That should give some protection and some of that foil heat shielding wrap may be useful near the muffler.

I need to check the evaporator. I think it may just have barbed copper pipe connections, but I can't remember.

Could be barbed but flare fittings were more common. If you are going to use R134 I would avoid barb fittings as the molecule is so much smaller it can escape places that would hold R12.

So would new fitting have to be soldered on?

If it is actually a barb fitting and you changed it then yes. Can't recall ever seeing a barbed expansion valve. Flares were the norm and am almost positive any modern expansion valve will not easily be found in barbed. Flare and O ring are the most likely found today. The suction side is most likely flared too -- typically would be a # 10 size but since it is a rear unit with a long run it could be #12. If it is barbed then with your new plumbing it would be the only connection left like that. I would use the correct size barrier hose and make sure it is properly clamped -- maybe even double clamped and see how it held before worrying about changing it.