A/C related questions

[71CHEVYSHORTBED402]

71 C-10 402........................I know, a lot of questions. My former co-workers loved it...........


1. Has anyone seen a reproduction for the compressor decal pictured below? There are similar on-line, but they don't read the same. This is a nice original decal, but the compressor should be rebuilt. It's not cost effective to send out when you can buy a rebuild for $200, paint and throw on a new label. Word is you can remove it "very carefully". I may test that theory out, but I can't imagine a great success rate. A heat gun might be the ticket.

2. Speak of these decals, why the variance in charge rates? For whatever it's worth, I hear GM used the same "A6" compressor from something like 1961-1972, and perhaps beyond. Maybe it's a variance of evaporators, condensers, and/or cooling areas.

3. The POA valve must be calibrated for R12 Vs R134A. This sounds like something that occurs when the system is charged as opposed a modification. Can anyone confirm?

4. I read where a condenser fan is recommended for R134A. Is this for cooling purposes and/or for longevity of the parts? Personally, I won't use the A/C much either way.

5. Are there aftermarket hose lines like originals or should you just restore the old rubber to maintain the look?


During my A/C homework and if it's any value, this is what I understand so far using the "original" system for R12 Vs R134.........Any additions and corrections appreciated.

A. Replace all O-rings for R134A compliance. These operate with R12 as well.

B. Does an original R12 Evaporator work with R134A? Just curious, I need to replace the Evap. either way.

C. Replace the drier for R134A compliance. The drier will work with R12 as well.

D. Calibration of the POA valve differs for R12 vs R134A. You can modify the system to run without the valve.

E. One A/C guy says the original condenser will run using R134A, while another A/C guy says the components for R134A allow for R12, but not the other way around. I'm replacing the condenser anyway. Unless you're a straight-up purest or happen to have one that's mint, I don't see an upside using an original condenser, despite the "original" truck restoration.

F. For what it's worth, one of the A/C guys, who's been in the business 45 years says a Vintage Air conversion adds value as compared to original or an "original" conversion to R134A. He "blames" the younger crowd. Personally I'll run an "original" conversion. Having the brackets, the cost for a restored system appears some hundred less, even with someone else restoring the boxes.

G. Sure a lot of variance in the cost for a rebuilt compressor and replacement parts. The cheapest is 45 year experience dude, and he's half the cost the most expensive. Nice personable guy too. Doesn't strike me as someone who sells trash.

H. Replacement condensers and driers bolt on as original. At least per my research anyway. Not sure about evaporators, but I imagine they do.


Appreciate it.......Thanks

[B. W.]

1. no
2. different charge rates for systems with more (or less) volume
3. POA should be calibrated, (different pressure setting, some are not adjustable) done before charging
4. no need for condenser fan if system is properly designed (in extremely high load climates not a bad idea though)
5. IMO, replace the hoses, especially if using R134a

B. original evap will work
E. newer condensers remove heat better
F. IMO, original system has more value on a "stock-ish" truck. Original system is a good design, will recirculate air or use outside air, aftermarket designs do not. If you want a clean firewall go aftermarket
G. recommend repair shop that offers a warranty on parts & labor. Most reputable shops have at least a 1 year/ 12,000 mile warranty (whichever comes first)
H. replacement evaps are a direct fit

[71CHEVYSHORTBED402]

Originally Posted by B. W.

1. no
2. different charge rates for systems with more (or less) volume
3. POA should be calibrated, (different pressure setting, some are not adjustable) done before charging
4. no need for condenser fan if system is properly designed (in extremely high load climates not a bad idea though)
5. IMO, replace the hoses, especially if using R134a

B. original evap will work
E. newer condensers remove heat better
F. IMO, original system has more value on a "stock-ish" truck. Original system is a good design, will recirculate air or use outside air, aftermarket designs do not. If you want a clean firewall go aftermarket
G. recommend repair shop that offers a warranty on parts & labor. Most reputable shops have at least a 1 year/ 12,000 mile warranty (whichever comes first)
H. replacement evaps are a direct fit

Now that was an education. Thanks a bunch B.W.

F. IMO, original system has more value on a "stock-ish" truck. Original system is a good design, will recirculate air or use outside air, aftermarket designs do not. If you want a clean firewall go aftermarket Agree completely.

G. recommend repair shop that offers a warranty on parts & labor. Most reputable shops have at least a 1 year/ 12,000 mile warranty (whichever comes first). Meaning I should put off the compressor until it's running (ground up restore). Wouldn't normally do that for OEM, but there doesn't to be a shortage on A6 compressors.

[F.A.A.benny]

Ive met Rudy a couple times at swap meets and have toured his shop. Had everything from a 65 Impala getting VA(he is a VA dealer) to newer model daily drivers getting ac repaired. He even had big buses getting air conditioning installed. He showed me the compressor rebuild area and it was honestly better than the one we had when I worked at Classic Auto Air.

[71CHEVYSHORTBED402]

Originally Posted by F.A.A.benny

Ive met Rudy a couple times at swap meets and have toured his shop. Had everything from a 65 Impala getting VA(he is a VA dealer) to newer model daily drivers getting ac repaired. He even had big buses getting air conditioning installed. He showed me the compressor rebuild area and it was honestly better than the one we had when I worked at Classic Auto Air.

And I appreciate the reference Benny.

[B. W.]

G. recommend repair shop that offers a warranty on parts & labor. Most reputable shops have at least a 1 year/ 12,000 mile warranty (whichever comes first). Meaning I should put off the compressor until it's running (ground up restore). Wouldn't normally do that for OEM, but there doesn't to be a shortage on A6 compressors.

I assumed you were going to have someone do the work for you (that's what I get for thinking!) What I've done in the past is mock up the system with an old compressor, replacing all other parts needed, then replace the compressor near the end of the resto work when I can charge & run the system. I'm gambling that all the other parts replaced will be good (they are all non-moving parts & the compressor is the most expensive) If a new compressor (or rebuild) is bad it will usually show immediately - noise, lock-up, incorrect pressures.

[71CHEVYSHORTBED402]

Originally Posted by B. W.

G. recommend repair shop that offers a warranty on parts & labor. Most reputable shops have at least a 1 year/ 12,000 mile warranty (whichever comes first). Meaning I should put off the compressor until it's running (ground up restore). Wouldn't normally do that for OEM, but there doesn't to be a shortage on A6 compressors.

I assumed you were going to have someone do the work for you (that's what I get for thinking!) What I've done in the past is mock up the system with an old compressor, replacing all other parts needed, then replace the compressor near the end of the resto work when I can charge & run the system. I'm gambling that all the other parts replaced will be good (they are all non-moving parts & the compressor is the most expensive) If a new compressor (or rebuild) is bad it will usually show immediately - noise, lock-up, incorrect pressures.

A mock up with the old compressor is a great idea. I'll do just that with the block off the frame. The downside of this project is I removed the system forward the "manifold" in 1993, and of course wasn't keeping a good record. But that's what I bought my 72 for (kidding, but it helped), so I have a respectable reference.

Only area I'm a bit stumped is some of the retainers forward the manifold. I had a bunch of retainers with the Compressor etc, all the years figuring it was all A/C..... Looking at my 72 and from other info......Most of it was for other components, some ID'd, some not. Here are the retainers if interested http://67-72chevytrucks.com/vboard/s...d.php?t=717950

[B. W.]

I remember that thread, the only one I was sure about was #2 & deadheadNM had already answered.

[71CHEVYSHORTBED402]

Originally Posted by B. W.

I remember that thread, the only one I was sure about was #2 & deadheadNM had already answered.

Thanks for checking. I'm most stumped on #1 & 7. Think I can edjuicated guess the others. I remember seeing #1 on the truck, but don't remember where. It may be for the alternator.