Classic auto air questions

[Pete in NH]

Bob,

I know digging into the assembled evaporator case is not going to be fun. It is the preferred way to accurately sense the evaporator temperature. I think the CAA guys were trying to do a shortcut. If you look in the FSM for the A body cars that cycle the compressor on evaporator temperature you will see the correct set up. You might try the adjustable thermostat switch and set it to a slightly higher temperature. For example the evaporator might be at 35 degrees and close to freezing and at the same time the suction line might be at 40 degrees. If you set the switch to trip at 40 degrees and turn off the compressor that might work. I'm a bit concerned that other variables might get in the way but it might be worth a try.

Dino, I see your problem now with the stock 69 expansion valve and two capillary tubes. Trying to mix and match stock system parts and CAA parts is the issue. You will likely need a single capillary expansion valve from CAA to match their suction line set up.

Your right it's a series electrical circuit so wire it up in any order that works best as far as layout. That thermostat switch you referenced sure looks adjustable to me, so it should work. Are you all squared away with the low pressure cut off switch mounting on the receiver/drier? There should be a small o ring under the switch and all o rings should be installed with a bit of refrigerant oil on them.

The model number of the compressor would help to tell us what weight PAG oil you need to get and figure out how much oil to put in the system. Too little oil and the compressor dies and too much oil and cooling performance is effected. Are the compressor ports sealed up now? Dirt and moisture are the enemy of A/C systems so system components should be capped or sealed whenever they are stored or before the whole system is connected up.

To flush out the compressor with oil first empty out whatever oil is in there. Then pour 2 to 3 ozs. into the suction port. Do this with the ports facing upward. Then turn the inner compressor hub by hand to circulate the oil. Then hold the compressor with the hub and clutch facing up in a vertical position and allow the oil to drain out. If the compressor has sat open uncapped I would repeat this at least twice before the final oil fill. All the system oil can be put into the compressor as it will quickly circulate through the system when the system is charged.

[green69rt]

Excellent thread on how these systems work.  I can maintain a system (freon fills, oil, parts swap) but never fully understood how these systems went together.  This thread goes on my bookmark list!!

[Dino]

Pete I did get the pressure switch issue resolved.  I had heard to use mineral oil on the green O-rings.  I bought a whole bunch of them a while back but don't have any oil yet.  Can I use PAG for that as well?

I have the expansion valve that came with all this stuff and it's all gently used.  It has only one capillary tube.  Can I reuse it?  It looks clean in and out.

I'll get a model number on that compressor tomorrow.

I tried to find a way to drill a small hole in the top of the A/C box.  The only way I can see this happening without taking half the car apart is removing the bulkhead connector (again) and try to drill a hole in the box through the revealed opening in the firewall.  IF it means the hole will be above the evaporator then It's worth a try.  I'll have to be real careful not to drill too deep though. 

I took two pics out of the A/C box restore sticky and circled the box bolt that can be seen in my pic under the bulkhead connector hole.  The part of the box that is visible has a narrow flat ridge and in incline.  I circled them in green on the other pics.  One shot is from the inside of the box so I just need to know where the hole goes, stick the thermostat's capillary tube in and screw the thermostat against the box or the car's frame.  Thoughts?

[Pete in NH]

Dino,

525 A/C mineral oil is better to use on the O rings. There is some thought that PAG can be slightly corrosive when exposed to moisture and air. I've always used mineral oil.

A used expansion valve is always a risk, if it is clean and the capillary tube is okay, it might be worth trying. Again when this stuff was removed from the original system it should have been capped off to keep out dirt. The risk you run is that if dirt did get into it, you may have problems with it in the system. If it turns out to be bad you will have to recover the R134 charge in the system and replace the valve and recharge the system. I'll leave you to judge whether you want to gamble on it. The other way out of this is to find an original Chrysler suction line rebuild it with new barrier hose and fittings to match the compressor and use the factory stock expansion valve you have. 

On the evaporator core and access to it, I couldn't find a good picture of the inside of a B body heater/ A/C unit. You want the capillary tube to run through the evaporator fins for at least several inches. I don't know what you'll get just drilling a hole and inserting the tube. I suspect CAA did it the way they did to avoid having to take the evaporator unit apart. But, as you know short cuts often don't work all that well. 

[Dino]

Hi Pete,

I would buy a new expansion valve but all the ones I find are the dual capillary type like the one I have.  Would it not work by cutting the one cap off?
I looked at the other valve that came with this system and it looks brand new.  The threaded ends were tightly wrapped in aluminum foil.  The capillary is not kinked and the curly end is untouched.  I wonder if the A/C place can do a flush before filling just to get everything out.  In any case, if I find a new single cap valve I'll buy it.

I always wondered what the evaporator looked like, the previous owner capped the ends but I have no idea how long it was disconnected before this was done.  Can I vacuum it out somehow?  Literally by capping one end and sticking the shop vac in the other?   

I removed the compressor and for some reason I thought it sat uncapped for a while, but it wasn't.  I think my old RV2 sat uncapped.  I removed the drain bolt, spun the hub and nice, clean oil came out.   
The drain bolt has a black rubber o ring, do I need to replace it?  Is it A/C specific?
There is not much info on this thing.  On the bottom of the body it says :7803 A04

I am divided on what to do with the thermostat switch.  I am a bit hesitant to drill into my A/C box blindly.  I was thinking about it this morning, what are the odds that I can drill a hole that would allow me to feed the capillary through the firewall, into the hole, and straight down between the fins of the evaporator IF that's where it is.  That does not sound likely to me.  It seems several people run it with the capillary wrapped around the liquid line's metal end without issues.  I guess it's better than not having one at all and maybe getting an adjustable switch will make the difference. 
Works case scenario that forces me to remove the whole box is that the lines and evaporator freeze, resulting in insufficient flow correct?  I may have to take the chance.  There just is no simple solution to this.  I still have a good amount of work to do on the car and I have not heard it's sound of music rattling out of the tailpipes since 8/18.  I wanna drive!   
Even after all this there will still be plenty work to do, but I can't do it all at once.  I will finally have some time off from school, after more than 3 years, and I want to enjoy the car for a bit before I tear into it again. 

I will keep looking for a way to get that cap in the box, but I don't see it yet.

[WHITE AND RED 69]

Thanks gentlemen, it's starting to make a bit more sense now.  Good idea using the fan bolt, I'll have to do something like that.   

Yesterday I decided to unscrew that brass thingy, I probably shouldn't have as it went psshhhhh.   

W&R that is the same spot on your drier where your switch is, but the fitting on my switch is smaller than the drier fitting.  Did you get an adapter?

Nope, no adapter. The switch came with the drier ($30 ebay purchase, the one CAA supplied was too small and didn't fit the stock bracket) so it was matched to fit.

Drilling blindly into the a/c box is a little too risky for my blood. You could be opening up a whole new set of problems if you damage the evaporator core. If you are not going to remove the box, then I would just run the tubes around the line. It might not be the best way but it does work fine.   

[Dino]

Thanks gentlemen, it's starting to make a bit more sense now.  Good idea using the fan bolt, I'll have to do something like that.   

Yesterday I decided to unscrew that brass thingy, I probably shouldn't have as it went psshhhhh.   

W&R that is the same spot on your drier where your switch is, but the fitting on my switch is smaller than the drier fitting.  Did you get an adapter?

Nope, no adapter. The switch came with the drier ($30 ebay purchase, the one CAA supplied was too small and didn't fit the stock bracket) so it was matched to fit.

Drilling blindly into the a/c box is a little too risky for my blood. You could be opening up a whole new set of problems if you damage the evaporator core. If you are not going to remove the box, then I would just run the tubes around the line. It might not be the best way but it does work fine.   

No, not pulling the box, not now.  The car would be on stands forever.

I'll get an adjustable thermostat and wrap the wire around the hose.  That's the hose coming from the expansion valve right?  Same spot as where you wrap the expansion valve capillary?  What is the tape called you wrap it up with?  Insulator tape?  I've seen a few tapes and I'm not sure which one to get.  Isn't this plain dum dum?

[WHITE AND RED 69]

Yep, all the tubes get wrapped around the line going to the evaporator and covered with the tape like in the pic ODZKing posted.

The tape used is called refrigerant tape or cork tape.

http://www.restomodair.com/view-all-products/small-parts/

You can also get a kit with the oil, o-rings, and tape from CAA for about 15 bucks.

[Pete in NH]

The 7803 translates to a Sanden SD7H15 series for a GM/Chevy application. It uses a PAG 100 oil. In an expansion valve system the compressor calls for 4.6 Oz's of oil. Oil circulating around the system gets trapped in various components about 2 Oz's in the evaporator, 1 in the condenser and .5 to 1 in the receiver/drier. So, I would use 8 to 8.5 Oz's as the compressor oil fill. The factory ships these compressors with 270 CC of oil which is about the 8.5 Oz's. Since you really don't know how much oil is in the compressor it is best to start fresh, do the oil flush routine and then fill with the final amount. The final fill goes in that oil drain/fill plug you removed and yes always use new  O rings whenever you remove one in an A/C system. You should be able to match one up from your O ring assortment.

There are two types of PAG oil around the older is a single end capped molecule the newer is double end capped. Find double end capped if you can it is less prone to absorbing moisture. You might also be able to find it with Ultra Violet dye added which would help in future leak detection. If not you can add the U/V dye later.

Expansion valves don't really flush out well because the orifice in them is so small.  You can try the single tube valve you have if you think it is really clean. I would not cut the second tube off the stock valve.

Flushing the evaporator with a small auto parts flush can kit really doesn't work well as you can't get enough flush solvent or pressure behind it. You don't flush compressors, expansion valves or most newer condensers.

The expansion valve capillary tube and if you choose to, the thermostat switch tube wrap around the suction line from the evaporator to the compressor. The line with the expansion valve is the liquid line from the receiver/drier.

[Dino]

Thanks guys!

I don't know why I keep mixing up liquid and suction lines, good thing I can't install them wrong!

I think I'm going with this switch as I can mount it on the firewall and still adjust the temp.
http://www.ebay.com/itm/261456058618?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
EDIT:  I see that is supposed to be for cable operation.  I don't plan on doing that as I could just as easily pop the hood and adjust it if needed, but is this the kind of switch I want?  It still cycles the compressor clutch does it not?

I can't seem to find 525 weight mineral oil, is there anything else I can use?

Can I use a green o-ring for the drain plug on the compressor?  I thought I couldn't.

[Pete in NH]

Dino,

You can use the green HNBR O ring on that compressor plug. I get almost all my Automotive A/C stuff from Arizona Mobile Air at ackits.com. They will have all the oils you need and I would give them a call and ask about what they have in the way of thermostat switches. I looked on their site the other day and they had several adjustable switches.I'd ask them about the expansion valve also if you want a new one. They should have double capped PAG 100 with U/V dye.

If you order your oil and supplies from these guys get some Nylog O ring assembly lubricant rather than mineral oil.
A small bottle of Nylog is better than getting a quart of mineral oil and the Nylog really works well on preventing leaks. Nylog for R-134 systems used to come on a blue bottle.

[Dino]

That Nylog looks pretty amazing.  I'm going to give that a shot.  Are expansion valves universal?  I did find some with only one cap so if they fit I'll get one of those instead of using the other one.  The switches are the same as the ones I found elsewhere.  I still want to use the last one I linked that is the slider type IF it works for my application.  Sure looks like it would work.

Is there a right way to attach the capillaries to the hose?  Does it wrap around it before taping it up or simply clamping it on there before taping?

[Pete in NH]

I would think all those thermostat switches you've looked at are intended to measure evaporator temperature and keep the evaporator from freezing but, it sure would be nice if they gave an approximate temperature range they covered.

The way the factory system placed the capillary tube from the expansion valve was to insert it in a special well in the suction line for about 4 to 5 inches. This gave a really good amount of contact area. From the photos that Bob posted of the CAA set up The metal suction line section is quite short so I don't think you have any other option but to wrap the capillary tube or tubes around as best you can.

Expansion valves are not truly universal, some are calibrated for R12 like your factory stock type and some of course are today calibrated for R-134. As far as inlet and outlet fittings I'm sure they have also changed over the past 40 years and it's likely there are metric pieces out there today. I would measure the diameter and thread count on your stock evaporator fitting and do the same for the liquid line CAA supplied. Almost everything round today is R-134 so that will likely not be an issue. The valve you want surely exists as Bob seems to have one on his car.

[Dino]

Yeah I'll find a new valve, I'll measure up the threads and go shopping.

What is a good temp range I should be looking for with the thermostat switch?

[Dino]

I took a gamble and ordered the lever slider thermostat switch.  For $15 it's worth a shot.  I also found and bought a new expansion valve, 32 oz of Supercool double end capped pag 100 with uv dye, which should be plenty to flush and fill the compressor, cork tape, and a bottle of blue nylog.

While I was shopping I found an old set of corbin pliers for $5 so I grabbed that as well.  I tried to put one of those heater hose clamps on with channel locks and spent a few minutes looking for the darn thing after it flew across the garage.   

[Pete in NH]

I've never seen temperature ranges specified on those switches even though it would be handy to know. I've had  asset of those hose clamp pliers for many years, it's amazing how far those clamps can fly when you try to use plain pliers.

It looks like you are well on your way supply wise. Are you planning on assembling the A/C system as soon as everything arrives? Also, Have you given any thought to vacuuming down the system and charging it with R-134?

[Dino]

I think the little corbin clamp almost reached 20 feet in the air so I'm glad it was going away from my face!

I should have everything here by next weekend.  I am unsure on how to proceed.  It will be filled with R134a so my thought was to assemble everything and when the car is operational again, take it to the mom & pop A/C place in town to have the system vacuumed, tested and filled.  If there's a better way to do it then I will revise my plans.  I can keep all the A/C parts off until the rest of the car is ready.  After assembling the A/C system and installing the new heater hoses, the rad and condenser, the under hood stuff will be pretty much done.  I still have plenty to do to the interior and I need to replace the trans pan and filter among other things.

[ODZKing]

I think the little corbin clamp almost reached 20 feet in the air so I'm glad it was going away from my face!

They are tough little buggers to deal with if you don't have the correct plyers for them.
These are like the ones I have. And even at that, they go flying sometimes.

[Dino]

I think the little corbin clamp almost reached 20 feet in the air so I'm glad it was going away from my face!

They are tough little buggers to deal with if you don't have the correct plyers for them.
These are like the ones I have. And even at that, they go flying sometimes.

Those look like the ones I just bought although they may not have the slider option, I'm not sure.  I'm not running the big rad corbin clamps yet so it'll work.

I think we can do some sweet corbin clamp distance flying competition with regular pliers!  Bring goggles.   

[Pete in NH]

Dino,

I think you could assemble the A/C system now and seal it up to be charged later. Remember to keep things sealed up and capped as you work and install the compressor second to last and the receiver/drier last. When you get it all installed and sealed up rotate the inner compressor hub clockwise 20 turns to purge any stray oil out of the compressor cylinders just before taking it to be charged. A good shop will know to do this but, I would feel better knowing it was done.

On charging the system, if you can rent or borrow a set of A/C gauges and a vacuum pump you could easily do it your self. You might want to check around with local auto parts places and see if they rent or loan out these items.

[Dino]

Dino,

I think you could assemble the A/C system now and seal it up to be charged later. Remember to keep things sealed up and capped as you work and install the compressor second to last and the receiver/drier last. When you get it all installed and sealed up rotate the inner compressor hub clockwise 20 turns to purge any stray oil out of the compressor cylinders just before taking it to be charged. A good shop will know to do this but, I would feel better knowing it was done.

On charging the system, if you can rent or borrow a set of A/C gauges and a vacuum pump you could easily do it your self. You might want to check around with local auto parts places and see if they rent or loan out these items.

Hey great idea!  I'll ask if they rent that stuff and if not I'll try the local tool rental place, they have everything.

Regarding the compressor, when I have flushed it and refilled with ~ 8oz, can I mount it with the ports to the side without oil running out when I remove the caps?  That is how the po had it mounted and it looked real nice as the big hose follows the heater hoses.

[Pete in NH]

I just looked at the picture you posted of the compressor mounted on the engine. Those compressor ports are almost horizontal on the bottom. I suspect the oil will run out positioned like that. I would attach the lines before mounting the compressor. leave the nuts on the line fitting slightly loose until you get everything in the final mounted position and the tighten them up. That will keep the oil in.

I bought a small vacuum pump and gauge set many years ago and I can't tell you how many times over they have paid for them selves. Renting would work fine and you might decide later you would like to have the tools. One thing I like about having the tools is I can take the time to really do things in  away a commercial shop really can't. I usually leave the vacuum pump on for at least two hours. The longer it runs the more water molecules I get out. Also, I like to let the vacuumed down system set over night. If the system is tight it will hold its vacuum reading over night and then I really know I don't have any leaks. A commercial shop just can't spend this kind of time on a job or at least you wouldn't want to pay for it.

[Dino]

I have a compressor and a brake bleeder vacuum pump but nothing for a/c.

I guess I can get these:

http://www.harborfreight.com/air-vacuum-pump-with-r134a-and-r12-connectors-96677.html

http://www.harborfreight.com/ac-r134a-manifold-gauge-set-60806.html

I picked the cheap vacuum pump because it is a simple device and should do the trick.  I don't want to spend +$100 on a pump right now.  $60 for the gauges is pretty decent I think.

Do I need anything else to do the whole thing besides R134a?  How much would I need and which coolant is recommended.

If mounting the compressor sideways is a bad thing then I will put it on with the ports up, but if it's okay as is then I'll do what you say and get the hose on loosely first.

[Pete in NH]

There's nothing wrong with mounting the compressor on the side like your photo shows, you just want to get it on without dumping oil out of a port.

The gauge set looks okay for casual work, that's all I have is an inexpensive set. That so called vacuum pump however, won't do the job in spite of what Harbor Freight advertises. Many people get fooled by that type of pump only to find out it won't pull a good enough vacuum. They wind up using a huge volume of air and still don't pull a good vacuum. you need to get down below 29 inches of vacuum. Only an electric motor driven pump can do that. I would rent one for now if you have to.

The only other thing you will need is some R-134A. Get only plain R-134A no sealers or other magic in a can. There is also no such thing as high mileage system R-134A, although they sell it, it likely has sealers in it.. You have U/V dye in your oil so you don't need that either. I can't stress enough how bad, bad, bad, sealers can be. CAA says there systems hold 24 Oz's of R-134A and I would start there. That's two 12 Oz cans, you'll need a R-134 can tap as well. I would get an extra can in case you have to add a few more oz's . If anyone reading this is curious about sealers I'll post why they are bad.

[Dino]

Good info Pete!   

I will look for a pump to rent, I just don't want to spend that much on a pump right now.  The gauge set is on sale for $100 so I'll definitely grab that.

I looked for refrigerant and had no idea so many had leak sealer in them.  Found this at Walmart which is conveniently located next to Harbor Freight!   

Looks pretty plain and not a bad price either.

http://www.walmart.com/ip/Speed-Steed-R-134a-Auto-Air-Conditioning-Refrigerant-12-oz/20440563