A/C System Advice Please

[Greg S.]

I have a 75 Convertible L82 4 speed purchased with original compressor in a box. Condenser is missing and compressor hose is cut. I want to reinstall A/C to function as new. Evaporator and Dryer are present. How should I go about getting A/C to work. I probably should just take it to an A/C shop but I like to learn how things work. I know I can buy the needed parts and manage to put it back together.

Should compressor be rebuilt since I know nothing about its condition? Who rebuilds original compressors so you get original back? Should I switch from R12 to R134? Know there are a lot of opinions about this. Most suppliers offer a VIR eliminator kit. Is this a good idea? I restored the heater A/C controller in the console. It should work as new. Vacuum hoses appear to be good. Dash and center stack are currently out of car. Should I do or check anything while dash is opened up?

Once it is back together I plan to take it to a shop to be evacuated and charged.

Need advice from those who have more experience with A/C.

[Terry M.]

Re: A/C System Advice Please

I have a 75 Convertible L82 4 speed purchased with original compressor in a box. Condenser is missing and compressor hose is cut. I want to reinstall A/C to function as new. Evaporator and Dryer are present. How should I go about getting A/C to work. I probably should just take it to an A/C shop but I like to learn how things work. I know I can buy the needed parts and manage to put it back together.

Should compressor be rebuilt since I know nothing about its condition? Who rebuilds original compressors so you get original back? Should I switch from R12 to R134? Know there are a lot of opinions about this. Most suppliers offer a VIR eliminator kit. Is this a good idea? I restored the heater A/C controller in the console. It should work as new. Vacuum hoses appear to be good. Dash and center stack are currently out of car. Should I do or check anything while dash is opened up?

Once it is back together I plan to take it to a shop to be evacuated and charged.

Need advice from those who have more experience with A/C.

If the descant package is still available for your VIR, I would replace that package when you have the cut hose repaired/replaced. VIR is a good system and there is no need to change or modify it unless parts availability is an issue, and I have no idea about that.

Before you assemble and try to get a shop to evacuate and charge your system, contact that shop and see if they will work with you. Many will only work on systems they have repaired. Long story why; but environmental and legal reasons are the short explanation.

AC work requires some expensive tools and some training. There is more to making your AC system work than just assembling the parts. It is not a DIY operation if for no other reason than the evacuation/charging machine costs around $5K and a purchase like that is impractical for a one time use for most of us. I know you said you were going to leave this technical stuff to a shop, but see above paragraph.

If there is a Community College near you find out if they have an Automotive program with an AC course. These courses sometimes require a prerequisite along the lines of an electrical course, but look into it none the less. It will be the least expensive way to DIY, but the car will have to be together enough to get it to the school's shop. Such a course will save you the cost of the equipment and give you the knowledge to know what you are doing and the skills to troubleshoot the system. In some cases the instructor may be looking for 'project' systems to work on, and while VIR is no longer used sometimes an 'antique' is a learning experience for the more open minded instructor and student.

You will want to replace all the O-rings in the system. A kit to do this is inexpensive and available from any REAL parts store – I prefer NAPA as opposed to the chain stores that generally target the least expensive part option.

I take it you don't know why the compressor was removed from the car. If that is the case you have two choices:
1) Rotate the compressor (not just the clutch) by hand and see how it feels. Is it smooth for 360* of rotation? If so you can roll the dice (In my best Clint Eastwood voice: ‘Do you feel lucky?’) put the compressor on the car with the cut hose repaired and a new descant package in the VIR and see if your shop will suck the dickens out of the system (<30 inches of Hg for several hours is best but good luck with that idea. Shop space and time is money.), put a limited quantity of refrigerant of your choice in the system and check for leaks. Flushing the system thoroughly before assembly is a good idea as well as draining and replacing the oil (See FSM or the above AC course for oil type and quantity.)

2) Send the compressor out for checking and repair as needed. There is someone on this board who repairs/rebuilds compressors, but I cannot recall who. Perhaps they will come forward and offer their own advice.

As to R12 or conversion. Talk to the chosen shop. There is another newer refrigerant than R134a that you may wish to consider because R134a is going away just like R12. Most shops no longer have equipment to work on R12, so your choice may be made for you. Do you intend to have your car judged? If so there will be a minor deduction for the R134a adapters that are required with that product. Only you can decide if that matters to you. Again, there is more to AC work than assembling the pieces.

[David K.]

Re: A/C System Advice Please

The new refrigerant is HFO-1234yf, I don't know much about it. It is in some 2014 Chrysler cars.Dave

[Larry M.]

Re: A/C System Advice Please

I have a 75 Convertible L82 4 speed purchased with original compressor in a box. Condenser is missing and compressor hose is cut. I want to reinstall A/C to function as new. Evaporator and Dryer are present. How should I go about getting A/C to work. I probably should just take it to an A/C shop but I like to learn how things work. I know I can buy the needed parts and manage to put it back together.

Should compressor be rebuilt since I know nothing about its condition? Who rebuilds original compressors so you get original back? Should I switch from R12 to R134? Know there are a lot of opinions about this. Most suppliers offer a VIR eliminator kit. Is this a good idea? I restored the heater A/C controller in the console. It should work as new. Vacuum hoses appear to be good. Dash and center stack are currently out of car. Should I do or check anything while dash is opened up?

Once it is back together I plan to take it to a shop to be evacuated and charged.

Need advice from those who have more experience with A/C.

Greg:

This question (or very similar questions) come up about once a year or so. Based on that, there is a LOT of excellent info in the archives or from previous years. Since I have been a part of most of these discussions, you can choose to search under my name to help limit the time.

The guy on this forum that does excellent compressor rebuilds is Domenic Tallarita out in California. I would contact him and discuss a rebuild/overhaul of the compressor. Phone is (760) 778-4944……or send him an email thru this forum. There are also two other places that do decent compressor work. If you need this additional info, let me know. But I would start with Dom.

Recognize that getting these old AC systems operating is either $$$$ or a "labor of love". I prefer to do things myself, but there is a lot of work involved.

The Chevrolet Service/Shop Manual is probably your #1 and best tool. Make sure to buy one for 1975 and read the HVAC Section thoroughly.

Most folks who do this work on their cars purchase a manifold gage set, a vacuum pump, a small dial thermometer, and a few other speciality tools. Again, most of these tools are listed in the archives, but I can supply more info if needed.

I prefer to stay with R12, but you can go to R134a if you wish. In a few years, 1234yf will probably be the refrigerant of choice by commercial shops. You can still buy R12, and you can also "qualify" yourself so that you can purchase legally, over-the-counter. It requires a 3-4 hours tutorial and open-book test with a few/various on-line companies. I have done this years ago. I can supply their names if needed.

You need to find a good place to buy replacement/reproduction AC parts for your 1975 car. I am mostly familiar with C2 years, so I don't have a good recommendation for you at this time. Paragon, or Keen, or Zip may be your best choice. Hopefully others will provide more/better recommendations.

http://www.autoacforum.com is a great place for AC info. Also Classic Auto Air in Florida and Old Air Products in Texas. Just Google for the contact info.

FIRST, get the 1975 Chevrlet Service Manual and read/re-read the HVAC Section (if you have not done so already).

Larry

[Steven B.]

Re: A/C System Advice Please

Greg, these guys may be able to help. They do installs, restorations, repairs, etc. and have a great reputation. They are going to do my '77. Steve

Phone Number: 817-531-2665
Fax Number: 817-531-3257
E-mail Address: chill@oldairproducts.com
Old Air Products
1201 Forum Way South
Fort Worth, TX 76140

[Greg S.]

Re: A/C System Advice Please

Thanks for all the great advice. I feel like I have a lot to learn. I will read the service manual and call Dominic.

[Domenic T.]

Re: A/C System Advice Please

Larry,
Thanks for the good words. That tell# has been out of service for years. I have had this new one since the early 90's. (760) 831-2095.
Greg,
All the advice is good that you are getting, I think that you should first do some of the things that were posted and see if you are lucky, like turning the hub to see if it rotates. you can also hear it suck & blow, or feel it with your fingers. If it turns then look for oil leaks where the 9 1/6 nut holds the hub on in the front. That will give you a clue as to a seal leak.
I think the question is Why did they remove it?

DOM