1970 ac system

[Steve G.]

Looking for advice - I recently bought '70 Vette (and subsequently joined NCRS club) with LS5, and ac. Trouble is, previous owner removed all ac parts in engine compartment except for the ac box. Even the evaporator lines were cut off at the ac box. I am looking to replace all these pieces. I see various aftermarket pieces (condenser, drier, lines, etc) online. Am I better off buying these used or new repro? I'd much prefer to keep the car factory correct, but am concerned buying used parts might spell trouble for ac system down the road because most have been left open to atmosphere. Any thoughts or advice (or sources for parts or restoration books) would be much appreciated!

[Dick W.]

Re: 1970 ac system

You are going to be a lot better off buying new pieces. Evap cores and condensers corrode internally, the compressor is available either new or rebuilt, the expansion valve is functionally correct but differs somewhat from original, and the hoses differ somewhat from original. If you expect it to operate reliably, the only way is new.

[Larry M.]

Re: 1970 ac system

Steve:

Agree with Dick....best to buy new or rebuilt original. Also recommend staying with R12 refrigerant. Prices are coming down and are almost "reasonable". It will cool/perform better, and you will be happier in the long run.

For information, go to www.autoacforum.com. Look under the "Automotive Air Conditioning Procedures, Tips, and Frequently Asked Questions" section. Lots of excellent info.

For tools, recommend www.ctd4ac.com

For parts including new, NOS, or rebuilt original recommend www.classicautoair.com and www.oldairproducts.com

Another good site for parts, info, schematics, parts lists etc is www.acdelco.com/html/pi_ac_catalog.htm. Check the "Application Catalog" and "Pictures/Illustration Guide".

"thepartsladi" sells AC Delco parts (for air conditioning and other) for reasonable prices and has an excellent reputation. Would consider her for AC DELCO evaporator and receiver/drier. She has an E-bay store and also sells on E-bay. Just "google" the name. I am not sure about the condenser. There may be more original looking ones from other sources.

Of course there are also a lot of excellent parts available from our NCRS Supporting Vendors. A listing is available at the top of this FORUM page. Check them out.

Also recommend the Chevrolet Service Manual for 1970 Corvette, NCRS Judging Manual, and a copy of the 1970 AIM. The Service Manual has an excellent AC section.

AC is expensive, just like the rest of the car. Let us know if additional help is needed.

Larry

[Dick W.]

Re: 1970 ac system

There has not been a 100% correct condenser made in over 20 years. Maybe longer

[Steve G.]

Re: 1970 ac system

Thanks. That was all helpfull information. Sounds like I should go repro for condenser and evaporator and the hoses. I did buy a used expansion valve that looks to be in very good condition, and a used compressor that I believe came off a '74 (again, my car is a 70). Would the used expansion valve be ok to re-use as it looks clean? Same question for a POA valve - ok to buy that used or should I go aftermarket? I have seen some used for sale for sale on Ebay. Also looking for misc parts - clips, brackets, and the inner fender sheild that protects the lines that go to the condenser as they pass around the radiator. Has anyone ever seen these come up for sale?

[Larry M.]

Re: 1970 ac system

Steve:

I would test the expansion valve before installing using an ice water bath for the temperature lead. Valve should begin closing as the lead gets colder. The expansion valve also requires a small debris screen with o-ring to keep it from plugging during service. Make certain the one you have has this screen.

POA valves can be obtained NOS if you are patient. But cost is pretty high ($200-300). Classic Auto Air sells rebuilt AND TESTED POA valves for about half this cost. There is also an NCRS member who sells used POA valves on E-bay. I would consider buying from him. (I have in the past.) He tests his valves before selling....which is a must. Do not just buy a used POA valve from anybody. They probably won't work correctly. Even the new/rebuilt ones can have sticking problems after awhile. EDIT: Also, there are three different models of POA valves, each with a different orientation for the small side connections. Be sure you get the correct one for your car.

If the contacts I previously gave you don't have the miscellaneous stuff you need, then try THE PART GUY at www.thepartguy.com. He sells used ac parts and can probably fix you up. I have not used him or bought from him...so suggest caution regarding what you buy.

Your used compressor will probably require a new seal...so plan to do it now.

Larry

[Steve G.]

Re: 1970 ac system

Thanks Larry. The Partguy link looks interesting. I may be able to buy the entire ac box / evaporator / valves from there if it is correct for 70. I am a novice when it comes to AC parts. When I do get all these parts, I am not sure I'd be able to get it running properly. After looking at some of the links, looks like lots can go wrong with these systems down the road. Does anyone know of a reputable business that restores AC systems for these cars in Massachusetts area?

[Jim T.]

Re: 1970 ac system

With the recommendatin for obtaining the service manual for your 1970 Corvette, if you buy one from the NCRS Store scroll on down their listing and you will see a March 1970 Chevrolet Service News (22 pages). The is a printing specificaly for the 1970 Corvette. If you buy the 1970 service manual you will find that on the cover it will say 1970 Chassis Service Manual Chevrolet Chevelle Monte Carlo Nova and 1969 Corvette.
I was surprised when I bought the 1970 service manual after buying my new 1970 Corvette. I later also bought the 1971 service manual because Helm did not send me the 22 page March 1970 Chevrolet Service News. Years later (about 20) after finding out about the 1970 supplement I contacted Helm and they sent it. The service news has a good bit of information concerning the 460 HP 454 (RPO LS7) that never made it to production.
Anyway the 1970 Chassis Service Manual has air conditioning information you can use. Has the wiring and vacuum hose diagrams. The left thumbwheel control unit in your console has 7 vacuum hoses connected to it. It also has a picture of the expansion valve and plainly shows the cone shaped screen filter that Larry mentioned.
I was away from home in 1988 when my wife contacted me about our 1970 Corvette daily driver's air conditioning not working. I told her to take it to the local Chevy dealer. They were going to replace the evaporator but could not get a big connecting nut loose so she took the car home. When I returned I read my service manual. Removed the line to the expansion valve and found the cone shaped screen completley clogged with disiccant from the dryer. I replaced the dryer and cleaned the condensor and line going to the expansion valve and cleaned the screen. Had the system vacuumed down, oil added, and new R12. It still works.

[Steve G.]

Re: 1970 ac system

Thanks for all the info. I will be buying the these guides and doing some reading. In meantime, if anyone knows of a good ac shop in or around Massachusetts, please let me know. Steve