hammmy

I have what appears to be a complete A/C system installed in my '80, but it hasn't ever worked in the year I've owned the car. I have no idea what condition it is in. I'd like to know how to start working on it, but I need some general help on what to do. I once loosened the hoses at the compressor to move them out of my way during a battery tray-area rust smack-down. I didn't do anything other than loosen the hose nuts enough to be able to turn the hose, so I'm unsure if that was enough to know whether the system is depressurized.

Assuming that the system is depressurized, and has been so for an indeterminate period, I would think vile nastiness has likely condensed inside the hoses and components. How should I go about cleaning the system? My first impulse is to disassemble the various components, and use compressed air to blow stuff out. How can I verify compressor serviceability?

I've read from Kevin's recent A/C thread (https://www.rx7club.com/forum/showthread.php?t=340442) that a new drier (the canister forward of the radiator?) and new O-rings for the hoses are mandatory service. However, I've also read that R-134a and newer refrigerants require hose upgrades, as the hoses are permeable. Where would I find "barrier" hose? I would assume I would need to fashion custom hoses, so I'd like to know what's necessary to make the high-pressure fittings. Obviously, I would like to avoid any answers that involve "take it to a shop" =). Also, where does one find the newer exotic refrigerants (non-R-134a)?

Any possibility of scanning Stu's '80 A/C manual, Kevin? I'm thinking a thread on this subject might be a good topic to add to the FAQ, especially for those looking to retrofit air conditioning onto 1st gens.

As an aside, I recently saw a thread regarding a how-to for installing a General Motors alternator into a 1st gen. Searching be "gm alternator" drops the critical "gm" (grr), so I didn't see anything close in the results. Anyone remember what I'm looking for? I have a bookmark I got from the thread (http://www.madelectrical.com/catalog/alt-1.shtml), in case that helps jog memories.

Oh, and lastly: please don't post any "just remove the A/C, windows are great free A/C" replies. If I wanted no A/C, I wouldn't trouble to restore it. Also, this "free A/C" in 90 degrees and hour-long stop-and-go traffic just doesn't cut it. And I'm talking WA state here, so I know it's murder most anyplace else.

Felgar

It's very likely that your hoses are leaking if it's never worked. There's an apparatus with pressure guages that is used to pressurize the system with refrigerant from a canister or whatever source... You'll need one of these to do work effectively.

My A/C experience stopped when I hooked up the guages and used my shop air compressor to pressurize the system - the hose leak was quick and simple to identify. I'd start there, to make sure nothing leaks. Beyond that add refrigerant and hope that your compressor still works.

Incidently the compressor won't even try turn on if the system doesn't have proper pressure...

That's about all I know - I'm sure others here are more familiar than I.

Pele

iTrader: (28)

Take it to an A/C shop and have then install a little bit of refrigerant and some UV sensitive dye for leak testing.

Hoses shouldn't be an issue with R134a, the oil used with it is...

That compressor needs lubricated, there's certain oil that atomizes in R12 and another type that works in R134a... The oils are not compatible.

I'd have the entire system flushed to clean out the old oil and contaminants, Vacuum leak tested again, and then charged...

Rx-7Doctor

iTrader: (13)

You are correct, you want to change out the filter drier. You are not going to know if you need any more parts until the system will hold pressure. Stay away from aftermarket freon like freeze 12 and such. R12 is very expensive and you cannot purchase it your self. Thers a chance that the old compressor is not strong enough
to handle the higher pressures of r134a. I recommend if your serious to change
out the compressor, receiver drier and expansion valve. Then take it into a shop and have them flush the system and retro to r134a, you will be much happier.
I recently did my mitsubishi eclipse to r134a and it blows ice cubes. rx7doctor
Ps, this was in 100 plus degree weather too.

hammmy

From what I've read today, I see that the receiver/drier/filter is a must for replacement with any refrigerant.

Lowest prices I've found:

http://www.ackits.com/merchant2/merc...t_Code=48693MD

http://www.partsamerica.com/PartDeta...pe=397&PTSet=A

Incidentally, this element appears interchangeable between all of the 12A A/C systems, as the first link is for an '84, while the second is for the '80. This follows intuition, as the thing is a simple passive filtering device.

Next, assuming I'm going to convert to R-134a, will I need a new expansion valve? Are these adjustable so that the existing R-12-compatible valve can be made to function with R-134a?

As some of you have pointed out, I'll need to flush and vacuum the system. The tools necessary for this are: a set of hoses with gauges, and a vacuum pump. I've seen R-12 hose and gauge sets on eBay for ~$30, but this presumably wouldn't help if I wanted to charge with R-134a. A suitable vacuum pump is apparently available through Harbor Freight for <$20.

None of this takes into account the condition of the compressor. For me, this is the critical factor, as I'm not eager to drop $350 for a replacement. So, I'd be willing to rebuild mine on the assumption that it is non-functional. I've seen a seal kit:

http://www.partsamerica.com/PartDeta...e=1227&PTSet=A

But this kit is for the factory A/C compressor. I have the dealer installed A/C, with the Sankyo Electric SD-508 compressor. PartsAmerica (Schucks, Kragen, Checker, Advance Auto Parts) lists a kit for the SD-508, but it is not currently available. NAPA does not list a kit online for either compressor. I'll have to check the dealer to see if they have one.

. . . and I'm spent. Will continue updating with whatever information I unearth. Thanks for the replies so far.

YapaKanichi

<wishing he had AC>

82SilverRX7

When I first bought my car I had a mazda dealer convert the ac to R-134a. Shortly after that it stopped working as in blowing cold. I figured the compressor just wasn't up to the task so I left it alone and drove it for like 8 months with windows down. Well this summer I got tired of it, and found an extra R-134a can and hose so I figured I'd play with it and see if I can hear a leak.

I got a can of R-134a with stop leak in it at autozone, and also a little bit of the original canister went into my compressor and ever since it's been blowing cold. I have no idea if the stop leak worked or not or even if I have a small leak somewhere, but it's been cold for 2 weeks now. I suppose I will but the dye to find any leaks if it stops again. At least I know the compressor works. The stop leak stuff also claims to "lubricate O-rings, and clean inside" so I dunno

Pele

iTrader: (28)

Ever see what Fix-A-Flat does to the inside of a tire... That's why I refuse to use it in anything with moving parts.

82SilverRX7

What does that have to do with it? I'm not putting fix-a-flat into my ac compressor ?

hammmy

Pele is saying stop leak of any kind operates on the same basic principle: insert goo into system that will hopefully gum up at the leak. In practice, stop leak gums up everywhere it settles, so you can expect restrictions in the system. Ever used radiator stop leak? It's a nice way to lose cooling capacity.

Pele

iTrader: (28)

Fix-A-Flat = Oil Stop Leak = Radiator Sealant = Tranny/PowerSteering/etc Stop Leak = A/C system sealant... All the same ****... Goo to be put in a system that shouldn't have goo in it. Fix the problems, mechanic in a bottle does not exist.

82SilverRX7

ok define goo..

on the can it says it's an oil added into the R-134a, which serves as a sealant to where there might be a leak. In my book, an oil is not going to "goo" up my AC system. doesn't matter all I know is I have ice cold a/c now so if it works it worked

hammmy

If it seals, it's a goo. It's that simple. The oil has an additive that's going to separate from the oil and coat everything, in a shotgun attempt to fix leaks. What, you think there's some kind of seeing-eye component in the oil that identifies leaks, and magically gives birth to a perfectly-sized patch?

hammmy

On the other hand, I'm with you on this much. If it works with no ill effects, then great. My A/C system is 24 years old. If I could add a stop leak to it to make it work, I would. I'm certainly not interested in replacing the A/C for more than what the car cost me.

hammmy

Ok, I have more research to divulge. I found out that Sankyo Electric--maker of the SD-508 compressor--rebranded in 1982 as Sanden, and continued to manufacture SD-508s.

Here's a service manual:

http://www.sanden.com/support/servicemanual/index.html

Here's a Parts page:

http://www.sanden.com/parts/index.html

The SD-508 parts are listed under the SD5 link on that page. There's also a link to a page that shows the oil required for the compressor.

However, these are just a listing of the parts that Sanden makes for repairing its compressors. They don't retail them from their site. So, I went all Hardy Boy again and found. . .

This: http://www.acsource.com/

On the lower left, you can see links to various compressor replacement part categories. Here's the major components I'm interested in:

Gasket kit: http://www.acsource.com/index.asp?Pa...ROD&ProdID=121

Seal kit: http://www.acsource.com/index.asp?Pa...ROD&ProdID=116

Clutch kit: http://www.acsource.com/index.asp?Pa...ROD&ProdID=339

Roughly, $125 would rebuild the compressor more or less completely. But wait, there's more. I stumbled on some other links while looking for a replacement parts source, and found this:

http://www.palshotrodparts.com/store.asp?ItemID=597

No mention of whether that's a new compressor, or remanufactured. At $189, I wouldn't much care, as that's ~$86 less than the remanufactured SD-508 (with clutch) that PartsAmerica.com offers. It's apparently pre-loaded with PAG oil, as the listing labels it as a R-134a compressor. There's also some nifty choices to be made, such as getting it with a serpentine pulley, or with rear exit hose attachments in order to lower the profile of the compressor in the engine bay. Not exactly a necessity in the 7's bay, but there ya go. You can also order several finishes, including polished at a $50 surcharge. That's actually expensive, as I saw another site (that I can't find at the moment) that listed the polished SD-508 at $220. Looked really nice =). Overall, the lowest price I've seen on the SD-508 (complete with a clutch) is $170. That site looked dodgy, however.

This link from Sanden shows the SD5H14, which is the R-134a successor to the SD-508:

http://www.sanden.com/products/piston5.html

This is apparently a swap-in replacement for the SD-508 that is upgraded and designed for R-134a. I've searched for a price, but have been unable to find one posted. I did send an email to these folks--http://acpartsnow.com/default.asp--asking for a quote, so I'll update if they get back to me. Speaking of them, I found these listed for the '80 RX-7:

http://acpartsnow.com/partslist.asp?...&oaaia=1192238

See the drier/filter/receivers for $6? Nice deal there, assuming S&H isn't insane.

Anyhoo, that's about all I've found so far. I'm leaning towards buying a new compressor now, instead of rebuilding mine. I'm going to be trying to ascertain whether my compressor works at all, and finding out how much the SD5H14 costs.

82SilverRX7

no but have you seen what blood does in an open wound? Magically coagulates and thats not even as thick as oil.. So I'm inclined to believe the oil in the stop leak could at least have the potential clean the O rings in the pressurized A/C system, not morph into a patch of weld over a gaping hole in my compressor. Maybe lubricate the hoses and provide a seal if a hose has a small leak.

I don't know, and I definitely don't have a phd in air condition technology, but as long as my a/c works I'll hold off believing others that state the oil goo will make it stop working.

hammmy

Believe what you like, just as long as you stop cluttering my thread with bull-headed retorts.

82SilverRX7

.

Stevan

iTrader: (17)

Here's some things that I've learned,

the vacuum thats neccisary if your system has been opened is to remove air, and moisture thats in the air. Water boils at 70degrees under near perfect vacuum (29.9Hg). A pump that is capable of this is around $200. The pump mentioned earlier for $20. is likely a venturi type that is powerd by compressed air,( you need a compressor) and will not come close to 29.9 inches of mercury. When moisture mixes with freon it forms acid that eats metal.
The receiver/drier has a dessicant in little bag/s that absorb moisture. I read a post on an AC forum by a lab worker, he said in the lab they would dry out dessicants by placing them under vacuum, and asked why do we need to replace it then? One of the pros on the forum replied, well its the only filter on most systems. I have also read that when the some dessicants absorb water it makes a chemical reaction that can't be reversed. I say all this about driers because the standard is to replace it if your system has been opened. Mine was $30. at Autozone, that one for $6. is a very good deal, make sure its the right one,(dealer air I think). Be sure to install the drier last and not to open it until then.
The different oils for different refrigerants also absorb moisture. Mineral and alkylbenzene oil willrelease it under vacuum, POE and PAG will not, PAG will also form clots when mixed with residual R-12 in your system. PAG is the oil provided in those Retrofit kits, these are known as death kits. The best oil for 134a is BVA100, POE is second.
Another thing about vacuum I forgot to mention, You have to charge the refrigerant directly into the vacuum, allowing no air to get in. Air is not condensible in the system and will cause high pressures.
I have more info, a good story about my adventure with reduced size barrier hose,but I type like a turtle, I will try later.

Please try not to knock the snot outta me if i've given any misinformation.

hammmy

The Harbor Freight pump I read about was supposedly capable of 26 inches of Hg. That's secondhand information, though. I'm probably not going to vacuum the system myself, unless an A/C shop wants ungodly amounts to vacuum and recharge the system.

I realized today, while putting on the Yoohoo belt, that my A/C was being run from the outside main pulley groove, instead of from the A/C pulley. So, I'm hunting down the correct belt (current one too short--A/C pulley much larger diameter).

hammmy

More nuggets:

$199 for a SD5H14: http://www.swacparts.com/Information/specials.htm

AcPartsNow.com quoted me $271.20 for a brand-new SD-508, and $296.51 for a new SD5H14. Oddly, the remanufactured SD-508 from them is $291, which is more in line with what the auto part chains offer.

AutoAirCompressors.com quotes $199 + $30 core charge for a SD5H14, so presumably $230. I hate when retailers list prices that way. Very deceptive.

Pele

iTrader: (28)

Ah.. I knew something was up... I have a clearly labeled Sanden SD-508 in my truck now. I knew it wasn't a Sankyo Electric and I knew it was a 508...

Nice... Now I know that I'll have a spare for the truck as I'm removing the A/C from the RX-7...

I'd get the A/C charged as that's the only way to spot leaks and test the compressor that way... So long as it wasn't run depressurized (Which is not likely as there's a pressure switch.) it should still be good.

Stevan

iTrader: (17)

That sounds like the way to go, they sell refrigerant with dye in it to find leaks.
On my system, I noticed black residue around the front of the compressor and clutch indicating a leak. Upon disassembly, draining the oil from each component (invert the compressor and turn by hand, also remove the fill plug on top, some may have a drain plug. To drain the drier, drill a hole in the bottom.) I got only 1/2 an ounce of oil, the system calls for 6.2 oz. So I replaced the front shaft seal, $20. from ACsource. Btw, my car sat for 5 years and the ac had no pressure in it.
To flush the compressor pour new oil in and turn by hand until the oil comes out clean, to flush the rest of the system, use brake cleaner in the hoses and laquer thinner in the condenser an evaporator coils, then blow out dry with compressed air. Note: you need to remove the expansion valve from the evap. coil to flush the coil, and replace the valve as mentioned by rx7Doctor if you are going with 134a, which I didn't learn until too late.
I will get to the reduced barrier hose(bad) story on my next post.

hammmy

Can someone give me a rundown on how the expansion valve works, and why it needs to be replaced? I've got a fuzzy picture of what it does. . .

Also, please illustrate why it needs to be replaced with R-134a.

Thanks.

Stevan

iTrader: (17)

I believe its because 134a has a different pressure/temperature than R-12, its higher.
The valve controls the flow of refrigerant into the evaporator coil. I have some pages from my haynes ac manual that I've scanned but they are too large to attach, I have to do somthing right now, I'll try to post them later.