Packard Forum Index » V-8 (1955-56)

Its not the expansion valve but the modulator valve that does temp control. Expansion valve is the larger valve with 3 caps or arms. When evaporator gets too cold the modulator valve opens to let the refrigerant go straight from pressure side of compressor to suction side. There is no flow thru evaporator so no more cooling. When the evaporator gets warm modulator valve closes and refrigerant has to go thru expansion valve and on to evaporator to get back to compressor.

Thank you for the clarification, Howard! Yes, I knew that but was writing with distractions so wasn't clear. I meant that I didn't realize that it attached near the expansion valve. That said, I'm not sure if I have it or the plate that these apparently attach to as the A/C unit I bought was piece-meal, and removed by a hired hacker to just threw all hardware aside without regard to its need. These is much I still need and while I am not going to get the A/C working just yet, I want to install it even before any restoration just to find what I need.

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A little more research indicates that apparently a longer vibration damper bolt is not needed after all. The parts book shows only the stock 3/4-16 X 1-3/8" long bolt, part number 440598, along with the 3/4" washer, part number 354301, but according to the installation manual, the washer is not used on A/C cars. Since it's probably a thick washer, not having it would compensate for the thickness of the extra pulley.

Also, rather than needing longer bolts for attaching the compressor to the head, instead it uses studs, lock washers and nuts to hold it on.

Studs are easier to position the compressor assy over for sure but be sure the length is correct. The nut at the rear of bracket is in the open and not bad to get to but the one under the compressor is a PIA and too long a stud will make it worse. Make sure the thermostat outlet is at the correct height too because the holes at the head have almost no slop and if the bracket is tilted more than a tiny bit things will bind.

The specification for the length of the studs is in the parts book but, of course, it makes no mention of how far they should protrude. Of course, using an educated guess, I would make them stick out only far enough for the thickness of the plate, the nut and the washer but no more than that!

I'll have to deal with the water outlet height when I come to it. I can't recall offhand how it's assembled but if it uses a crossover, perhaps leaving it slightly loose, then tightening if after the compressor is the way to go.

Maybe remove compressor, drill access hole for bolt, tap it an install a plug in the hole.

IT's only oil that could possibly leak if plug were loose or somethin???. NOT refrigerant? Still a PA to have to remove pump to remove bracket tho.

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I'm not sure what you mean.

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Not possible. On factory assys, the bracket is actually part of the compressor and forms the bottom of the crankcase. 10 bolts hold the compressor body to the bracket and those come in from underneath. Everything would have to be off to access the bolts so that kind of puts a kabosh on an access hole. The crankcase is open to everything inside so refrigerant would leak along with the oil.

IIRC, I used a universal socket and 12" extension to get to the nut. With the single carb there is a good angle but with duals it is a bit more work.

HH56. Thanks for the clarification on the compressor bolts.

Does anyone know if the two SAE bolts at the thermostat to A/C compressor bracket are grade-marked and if so, which grade? Do they have lock washers under them? The parts book does not show lock washers which was a surprise. How much of these bolts us threaded?

On the bracket to head studs, how long are the threads on each end?