I recently (mid-July 2021) had my A/C system evacuated of R134 on my '69 4-4-2 convertible so I could remove the compressor to get it rebuilt. I just now received my newly rebuilt compressor. Everything I read says I need to replace the dryer and the expansion valve before I hook everything up again and charge the system. Is that really necessary? Both items are about 5 years old and have been used for a total of no more than 2 hours during that period. When I had the system evacuated in July, I closed the two open ends with rubber plugs to keep contaminants from entering. If I still need to replace those two items, could someone explain why to me so I know the reason for changing out these items (yet again!).

Randy C.

 

I would say no on the valve, and yes on the dryer. The dryer absorbs the moisture in the system. The cost to buy one is pretty cheap if you look around. It's cheap insurance, but if it is as you say then you probably could run it as is. The thing is it's $30.00 vs the time to evac and purchase/install/recharge later.

 

I agree on the expansion valve - no need to replace that. The drier may be OK to reuse since you had the lines capped.

 

Why was the compressor rebuilt? That could change the expansion valve answer.

Yes to changing the dryer, they are not overly expensive and it is best to get and keep every bit of moisture out of the system.

Good luck!!!

 

I had the compressor rebuilt because either it or the clutch went out on me. I was driving home on the hottest day of the summer and everything was fine until I had to slow down and then stop at a light. I accelerated when the light turned green and I started hearing "squeeky" noises that I'm sure was from either the compressor or compressor clutch. It would come and go and after about 15 more minutes it locked up and burnt the belt off of the pulley. The noise sounded like a bearing or bushing going bad. I had the system evacuated of R134, then removed the compressor and had everything gone through with it. There's a place in Texas (Old Air Products) that will rebuild everything without destroying the Frigidaire sticker, which I wanted to keep to maintain the originality look under the hood. And now, I have the rebuilt unit on my shop bench ready to install before I take it to the A/C shop so they can flush the system and re-charge it. I have no issue with changing the dryer. The expansion valve looks..."difficult"... but I just scratched the surface on how to remove it if I need to do that.

Randy C.

 

If the system is being professionally flushed I would try the existing expansion valve if the system was blowing cold just before the compressor failed. The concern is whether or not debris is in the valve, consider discussing the valve replacement vs. flushing with the shop that will do the work. Again, I'd try the current valve.

Ask them if they would give extra time while evacuating the system. Evacuating causes the moisture in the system to literally boil out because of the lowered boiling point of the system under vacuum. Moisture in AC lines is BAD, that's why we are saying to replace the drier.

Good luck and kudos for going so far to keep it original. Those are the details that stand out.

 

Since the system was opened to the atmosphere the dryer HAS to be replaced, don't install the new one until you are ready to vacuum the system immediately. You should do the expansion valve as cheap insurance while the system is apart, remove the old one before you flush and use new green o-rings everywhere you disconnect.

 

If the compressor is what seized, it could have put some junk into the system. That why the rebuilder wants it replaced and may affect the warranty. Drier must be replace anytime the system is opened, moisture in the system will freeze at the expansion valve and cause the valve to not operate properly.

 

Well, another setback. I was examining the compressor closely and I discovered it got damaged in shipping. Somehow, the metal plate on the front of the clutch got bent and pushed back hard into the pulley. So, no matter what, the clutch is always engaged. Fortunately, I didn't have the whole thing installed before I discovered this problem. The compressor will be on its way back to Forth Worth tomorrow to get that problem fixed. I plan on changing the drier - not a problem although I had forgotten what a treat it was to get the passenger side grill off the car so you can get at the old drier. I'm going to leave the expansion valve alone; in looking at it closer the expansion valve appears to be original to the car. The compressor has always been the problem with this car and I'm pretty much at my last straw with it. This is round two with the compressor and if the darn thing goes belly-up again, I'll just find a replacement.

Randy C.

 

Correct. This is why a vacuum of 30" Hg or better for an hour or longer needs to be applied - the water will boil at low pressure and the vacuum pump pulls the water vapor out of the system.

 

We need to know the pressures.

 

10X replace the dryer.
I've had the dryer cut open desiccant replaced and welded back together. Comes back like new with zero hints of china.

 

FINAL UPDATE: Replaced the dryer, got the damage to the clutch on the compressor fixed courtesy of Cold Air Products in Texas (who rebuilt the compressor), assembled everything, got it charged with R134, and it lasted about a day before there was no charge left. Went back to the business that charged the system. They said they checked for leaks and found none but they would look again. What they found was the high and low pressure shrader valves were bad so both were replaced. Since then, the cold air has been working nicely!

One thing I've noticed is the vents for the A/C system really aren't that great, compared to newer cars. Yes, the system definitely blows cold air and, if you are the driver or the passenger in the front seat, it works good for you. But if you are in the back seat, it seems that not much cold air reaches back there.

Bottom line - it works, finally, after being "dead" for at least 38 years!

Randy C.

 

Is the condenser the original one installed in the car when new?
The reason I ask has to do with paralell v.s. axial flow condensers.
One type worked well with R-12, but with R-134, not so much.
Check with Old Air Products, They may have a condenser that works with R-134 and will give you all the cooling you need.

 

Yeah, I realized 20+ years ago the fan on newer vehicles moves a LOT more air than our old Oldsmobiles.