Any years 1976 AC questions

[shadetree39]

After several  hours of run time after a 30 year rest the AC compressor seized.  A bypass belt was tried but a 48 inch squalled on start up and when the steering wheel got near lock. I couldn't get a 47 inch on. I had thought that I would skip getting the AC working til a later date but decided to replace the A6 compressor. Doing this at home with no way of capturing the R12 of course I unhooked the hoses slowly and nothing came out. Good, I didn't destroy the ozone layer.
Draining the unit also produced nothing but a very small amount of rusty looking oil.
Rock Auto supplied a rebuilt unit already charged with 3 oz of oil and R134 ready.
The clocking of the 2 tab connector was about 180 deg. off but the pulley ID is 5.12 as opposed to takeoff of 5.5inch.
Question 1, should that unit be returned for one with 5.5 inch pulley?
Question 2, how does one determine the amount of oil in rest of the system ? the manual says  10 oz.
Question 3, will the precharged amount sustain the system even if its not recharged with R134 and unused?
What else in the system needs to changed to accept R134?
I assume the system would need a professional drying out before charging.   
My goal is have the AC system preserved enough for next owner of this terrific car to fix if desired.


 

 


 
 

[Big Fins]

Power connector should be in the 10:00-11:00 o'clock position when looking directly at the unit from the front.

The 10oz of oil should be distributed throughout the system adding to each component. Compressor, VIR, evaporator and condenser.

If you don't plan on using it, why the big bucks to replace it? Unless I were out for a completely original system, I would have replaced it with a compressor capable of compressing R134-a to the proper pressures. An A-6 won't be efficient.

You're going to need to replace the hoses, flush and pressure check the condenser and evaporator, have the VIR rebuilt or use Old Air Products' VIR replacement system. You also need to be sure the programmer and head unit are operating properly.

[TJ Hopland]

When you were trying the shorter belt were you trying to tension the belt by moving the power steering pump?  That's how its supposed to work.  Its kinda a pain to access the bolts, I think there are 3? and its really a multi person job since someone has to hold the belt tension (without damaging the pump) while the other person tries to tighten the bolts.  If you were just trying to walk the belt on with no adjustment that was likely your issue.


Let me make sure I got this straight.  This car sat for 30 years?  Then was revived and on the road again.  AC didn't cool at that time which is no surprise after sitting for 30 years but you didn't care or try real hard to get it going.  Started driving the car and started getting bad noises and belt slipping/destruction issues?

If that is the correct sequence I have questions.  At any time of the revival process did anyone note if the clutch was engaged?  The pulley is always turning with the engine but that hub part that is in front of the pulley is attached to the drive shaft of the compressor so that is how you can tell if its engaged.

These have a low pressure switch but it runs through a time delay of sorts called a thermal fuse. It doesn't look like a fuse its just a black blob with 3 terminals on it.  I have run into a lot of these where at some point in their lives the fuse blew likely due to low refrigerant.  For one reason or another instead of replacing the fuse someone just bypassed it which means there is no longer any sort of low pressure cutout so no pressure which also means no oil clutch is going to try and stay engaged and run unless you are in OFF or ECON.

When I do a revival especially on these before I start it up I pull the electrical plug off the clutch to be sure it doesn't try to run till I have the time to properly explore the AC system to make sure it is in working order and doesn't have things like the pressure switch and fuses bypassed.  I wish I could say I read that or was taught that but no.  I learned that the hard way and had a small fire as the belt burnt up and then tried to drive one of these boats without the power steering.  Not something you want to attempt at lower speeds.

If the clutch was engaged then what likely happened was the compressor did seize up so then it was a combination of belt slipping and clutch slipping heating things up making each one worse and fail faster.  If it wasn't electrically engaged the condition of the compressor doesn't matter all you need is the bearing in the pulley to be fine and they usually are,  its a decent sized bearing. 

The way the setup works is the compressor has a hollow snout on it.  The pulley has a bearing in it that fits over the snout. At this point you just have an idler pulley.  The compressor drive shaft comes out the hollow snout and has that drive hub clutch plate thing you see in the middle of the pulley.  They stick an electro magnet behind the pulley and when its energized it sucks the clutch plate hub thing into the spinning pulley and you are now driving the compressor. Magnet off springs let it release and the pulley is just spinning on its bearing.

IF the clutch and or the belt was slipping in addition to possible physical damage to things it tends to get hot and cook the grease out of the pulley bearing so even if you did find at this point that it was electrically engaged and unplug it it may not be reliable just as an idler because the bearing is shot.           

[dplotkin]

... I would have replaced it with a compressor capable of compressing R134-a to the proper pressures. An A-6 won't be efficient...

Who taught you that? Not true at all. I run 134A in a 62 Bonneville, completely stock system with A6. Delivers 42 degree air no problem for the last 12 years without even a topoff. . I have several or more friends doing likewise.

Dan