Hello,
I have an 86 with the 305. The A/C has been converted to 134 by the previous owner. Today I was driving and it got warm, so I decided to run the air. I turned it on and nothing happened. In my car, I can always tell when it's on. I got back, and sure enough, the compressor was not engaging. Previous to this, it has worked fine. Last August, I topped it off with refrigerant, but it was not that low. It worked fine all throughout the rest of the summer and the fall. Now it won't turn on. I was searching around and I came across http://www.elcaminocentral.com/showthread.php?t=24480
which seemed to suggest that the cycling switch was bad. Could this be it? Or do I need a new compressor? Could it be the switch in the passenger compartment? Or could the refrigerant have leaked out this quickly? I'm a bit skeptical about this last theory because my grandparents had the car before I did, and after the air was changed to 134 in 2001, it always had cool air. The only time it got topped off was last summer.
Thanks,
David

Try appling 12 volts to the compressor clutch to see if it's operational. Don't forget to ground the other terminal. ou should see and hear the clutch engage when 12 volts are applied.


Danny :cali:

Your freon level is probably low again. When it gets low enough, the low pressure switch will keep the compressor from running. You may want to recharge with a dyed freon this time to help locate the leak. You can jump out the low pressure switch momentarily to see if the compressor starts. If it does, you are probably low. Bad switch would next.

Try appling 12 volts to the compressor clutch to see if it's operational. Don't forget to ground the other terminal. ou should see and hear the clutch engage when 12 volts are applied.


Danny :cali:

Could I please have specifics on how to do this? Thanks!

I looked for a picture to post but could not find one. Look for a two wire switch mounted in the accumulator (aluminum tank @ right firewall). A/C on, unplug the wires going to the switch and jump them together with a short wire etc.. If the compressor starts, there is where the problem lies.

Great, I'll try that and post the results.

So I jumped the wire and the compressor started. So either all the refrigerant leaked out or the switch is bad (I think the switch is the problem). So what I'm wondering now is which switch to buy. Autozone, Advance auto parts only listed one switch, but Oreilly auto listed a R12 switch and a R134 switch. I have R134. Is there actually a difference? Second, how do I replace this switch? Will I lose refrigerant? Is it under pressure and if so will taking the switch off cause explosions? Thanks again!

Yes, you will lose refrigerant and have to evacuate and recharge the system. I am an A/C tech and I'd be really surprised if it was the switch rather than the refrigerant level. If you don't have a gauge set for it, you can buy a fill hose with a gauge built into it. Hook it up and jumper the switch to run the compressor. If it is less than 40 PSI running, add refrigerant.. Once it is running at over 40, disconnect the jumper. I'll bet the compressor continues to run.

Ditto, would be surprised if it was the switch. Just put that on as a possibility, have not seen one go bad.

My 84 has a schrader under the cycling switch which allows it to be unscrewed without loosing any refrigerant. The only difference between the r12 and the r134 switches is the pressure setting that it cycles at. r12 about 30 lbs and r134 about 20 - the best I remember and you know how that goes so correct me if I'm wrong.

Time for Robert to check in.

I probably won't get around to it until this weekend again, but I'll add some refrigerant and see if that works. IF it doesn't and the switch is the problem, would I need to have a shop replace it since they could deal with the pressures? I'll definitely try the refrigerant first though.

Better check all Crimped hoses they where Bad about leaking and Gm had hose clamps to replace the Crimps The hose clams Had a metal tang that cliped onto the end of the Hose realy its just a hose clamp But the original Crimps Leaked,xGM master Tech info changed mine now no leaks Just my 2 Cents :texas:

Colorado needs A/C in February........New Mexico has -40 degree windchills......Did I move too far south when I left Wyoming 24 years ago? I need a hug and a cookie.....I'm nervous
Craig (Juarez here I come)

Colorado needs A/C in February........New Mexico has -40 degree windchills......Did I move too far south when I left Wyoming 24 years ago? I need a hug and a cookie.....I'm nervous
Craig (Juarez here I come)

Well, I'm at the University of Colorado at Colorado Springs. Two weeks ago it was -30. Yesterday was 70 and I just wanted to see if it worked. I always heard it was good to run it periodically to keep things lubed up. I guess I don't NEED it...:nanawrench: but I will need it when I go back to Grand Junction in May.

Tires have more pressure that a lot of a/C systems, so the pressure is not an issue. If the switch has a valve below it, you can swap it without losing any refrigerant or even getting your hands dirty. I'm still betting the switch is fine. If i does not have a valve under it and you get to here the hiss of the refrigerant venting, you will have to have the system evacuated and recharged. So loosen the switch and see if it leaks. If it does, have it swapped by a shop so they can recover and re-use the refrigerant.

I probably won't get around to it until this weekend again, but I'll add some refrigerant and see if that works. IF it doesn't and the switch is the problem, would I need to have a shop replace it since they could deal with the pressures? I'll definitely try the refrigerant first though.

Thanks for all the information. I probably won't get around to it until this weekend. I'll post what I find out.

FYI, the molecules of R134 are smaller than R12. New hoses are made with a barrier that will hold in the R134 molecules. The older hoses will tend to bleed out the R134 over time, just due to the spaces inside the hoses that allow the R134 through.

FYI, the molecules of R134 are smaller than R12. New hoses are made with a barrier that will hold in the R134 molecules. The older hoses will tend to bleed out the R134 over time, just due to the spaces inside the hoses that allow the R134 through.

While that was true in theory, it's proven not to be an issue over the years.
All old AC hoses had what was called ambient leakage, regardless of the refrigerant. It turned out to actually be no worse with R134a.
Barrier hose was developed (mandated) to reduce ambient leakage, as were the green HBNR orings.

Okay, I just got a DIY can with a gauge at Walmart. With the compressor off, it was reading 25ish pounds. With the compressor jumped (and thus engaged) it read 0. So I added some refrigerant. I then plugged the wires back in and the compressor worked, but it turned off and then on, one second for each. So then I checked the pressures again, and with the compressor engaged it was just above 0, but with it not engaged, the switch went way up to 45(?). So do I need to continue adding more refrigerant?

The short answer is Yes, you're still way low on refrigerant. At 25 psi the system is basically empty and you have a leak. It's also possible that 25psi was mostly air.

What you really need to do is:
-Throw that Wal Mart can in the trash where it belongs.
It likely contains a bunch of snake oil that has no place in an AC system. The gauges are notoriously inaccurate too.

-Rent a proper set of gauges and a vacuum pump.
Many chain parts stores have them for a refundable deposit.

-Find and repair the leak.
You can reseal all of the connections for about $10 in orings.

-Pull a hard vacuum on the system to remove any air and boil off any moisture.

-Charge the correct amount of virgin refrigerant in by weight.

So I don't know how to do this, so how much would this cost for a shop to do?

There's too many variables to guess. Location, local labor rate, what is actually leaking, etc. AC work can get expensive quick when you hire it out.
There's also the age of the car to consider. On a newer car, you can usually fix a leak and the system will be ok for a few years. On a 25 year old car, it's a roll of the dice. Like many other systems on an old car, a simple AC repair can snowball quickly.

If it's only 1 oring fitting leaking, you may be looking at a $100-125 repair. That's not bad but there are still several more 25 year old orings in the system. There's also 25yo hoses and a compressor shaft seal of the same vintage. Any one of these things could fail from age soon after paying for a single leak repair.
Looking further, the desiccant in the accumulator is 25yo and should always be replaced if the system is opened for major repair. The oil in the system is also 25yo and in need of replacement. This requires flushing.

It's quite possible that it could get into the $5-600 range to do the job correctly and make the system reliable again.

Doing the physical replacement of the parts your self is the best way to go if you're mechanically inclined. You can then have a shop evacuate and charge the system.
If you can't do the work yourself, then find a competent AC shop and talk to them. Have them check the system over and get an estimate, then decide from there.

Alright, thanks. It was converted to R134a about ten years ago. I do know the compressor is that old. I don't know if that makes a difference on which other parts have been replaced or not. I wouldn't mind doing this myself, but I've never delved much farther than figuring out what parts are which and adding refrigerant in the low side service port. Thanks to everyone for the info and keep it coming!:You_Rock:

If you want to try and tackle the job (mostly) yourself, it's not hard at all. Your car uses what's called a Cycling Clutch/Orifice Tube refrigerant loop. Except for the compressor there are no moving parts, like the POA valves, suction throttling valves and expansion valves used on older systems. That makes the system almost "newbie proof".
You can easily do the job on a weekend if you get the parts ahead of time. You will need access to a good supply of compressed air for flushing, though.

The first thing you need to do is try and locate any existing leaks. You can often find them with a visual inspection alone. When the refrigerant leaks out, it takes some of the system oil with it. This oil collects at the leak site and grabs underhood dust and dirt like a magnet. Although you will be resealing all of the connections, the idea here is to find out if there are leaks in any major components.

Follow the lines and look at all of the oring fittings, crimped hose connections, etc. and see if there is any oil/dirt accumulated.
Look closely around the compressor clutch and body for oil/dirt. Shaft seal leaks can be elusive. (also pay attention to the compressor manifold connection and the pressure relief valve on the rear of the compressor).
Look closely at the condenser for oil staining. My 78 had a leak in the condenser that only showed up on the back side facing the radiator.
Note: There's no good way to visually check the evaporator without removing the top half of the evaporator case and pulling it out. It's pretty easy but it requires some disassembly. The good part of doing it is that you can clean the 25+ years of dirt, dust, and debris out of the box. It's unbelievable how much crud gets plastered on the evaporator. Pulling the evap. to check it is a judgment call.

Take a good look see at it and post back what you find.

I forgot,
When the conversion was done, do you know:
-was the compressor replaced? (you seemed to indicate that).
-was the old R12 oil flushed out?
-was the accumulator replaced?
-What type of oil is in the system?

If the conversion was done "properly", the system would have been flushed and the accumulator would have been replaced along with the orifice tube.
However, many "conversions" are done by just screwing on the adapter fittings, adding Ester oil to the old oil, pulling a vacuuum and gassing it up.

The compressor was replaced in the late 90s or early 2000s. It was converted to R134a at that time, which is what is in it now. I have not idea if the accumulator was replaced. It does have a high and low side service port on it...
I do know that it has R134a in it now.

The compressor was replaced in the late 90s or early 2000s. It was converted to R134a at that time, which is what is in it now. I have not idea if the accumulator was replaced. It does have a high and low side service port on it...
I do know that it has R134a in it now.

Ok, cool.
Look that compressor over really good for signs of oily dirt or oil "staining" like I mentioned.
10 years is a fairly long time but it may still be ok. Swipe a business card in between the clutch and pulley as far as you can get it. Dust from the clutch face is ok, but if it's oily then the shaft seal is probably leaking.
If the compressor is ok, that takes an expensive part out of the equation.

Does anybody know how many pounds of refrigerant these systems hold?

Web....I want you to know that I just braved the cold night in my Superman pajamas to go out to the shop to look up the capacities.
1986 Official GM Shop Manual: not a clue....safety tips everywhere...but no figures
1980 Official GM Shop Manual: nice little box with 3 lbs 12 oz listed as A and B body capacities...ours are the same as A bodies....before we became G bodies.....but that's not what you asked so forget I wrote all that.....however those are R12 capacities so your mileage may vary
Craig (was knowing about my Superman pajamas too much information?)

Web....I want you to know that I just braved the cold night in my Superman pajamas to go out to the shop to look up the capacities.
1986 Official GM Shop Manual: not a clue....safety tips everywhere...but no figures
1980 Official GM Shop Manual: nice little box with 3 lbs 12 oz listed as A and B body capacities...ours are the same as A bodies....before we became G bodies.....but that's not what you asked so forget I wrote all that.....however those are R12 capacities so your mileage may vary
Craig (was knowing about my Superman pajamas too much information?)

Hey, thanks for braving the cold for me! I appreciate it:You_Rock:
This was just figuring out how much refrigerant will cost. This gives me a ballpark on how much I'll expect to pay for refrigerant. Don't worry about the superman pajamas. I have Charlie Brown lounge pants, and I knew someone who had Monty Python and the Holy Grail Pajama lounge Pants.

I'm going to take my shop because I don't quite know what I'm doing, and being in college, I don't really have time to do too much myself. Thanks to everyone for all the help, and I'll post more questions if they come up.

Does anybody know how many pounds of refrigerant these systems hold?

52 oz. R12, subtract 20% for HFC134a = 41.6 oz.

This is a good starting point, but may require some finesse to nail the charge.
Charge with no more than 46.8 oz.

I give you the amounts only as a guide so you know how much you need to pay for.

If you do not have a full set of gauges and do not know how to read and interpret both the high, and the low side pressures, you should not attempt charging on your own.

Do not use Walmart or or other "suicide" kits.

52 oz. R12, subtract 20% for HFC134a = 41.6 oz.

This is a good starting point, but may require some finesse to nail the charge.
Charge with no more than 46.8 oz.

I give you the amounts only as a guide so you know how much you need to pay for.

If you do not have a full set of gauges and do not know how to read and interpret both the high, and the low side pressures, you should not attempt charging on your own.

Do not use Walmart or or other "suicide" kits.

I kind of figured that I shouldn't try doing too much. I'll be taking it to a shop probably early next weeks. Thanks for the info. Now I know how much I'll have to pay at $25 per pound of refrigerant...

Put T-bone steak in it......lots cheaper per pound and steak
won't harm the environment.
Craig (close to dinner time)

Put T-bone steak in it......lots cheaper per pound and steak
won't harm the environment.
Craig (close to dinner time)

Ha ha that sounds good right now. Sure would beat this cafeteria food!

Ok, cool.
Look that compressor over really good for signs of oily dirt or oil "staining" like I mentioned.
10 years is a fairly long time but it may still be ok. Swipe a business card in between the clutch and pulley as far as you can get it. Dust from the clutch face is ok, but if it's oily then the shaft seal is probably leaking.
If the compressor is ok, that takes an expensive part out of the equation.

So I took a close look at the compressor between the pulley and the actual compressor part and I noticed what looked like a dried oil stain on the compressor part between it and the pulley. I'm beginning to wonder if that is where the leak is...

I should also mention that the compressor was always noisy when first started, back when the a/c worked.

So I took a close look at the compressor between the pulley and the actual compressor part and I noticed what looked like a dried oil stain on the compressor part between it and the pulley. I'm beginning to wonder if that is where the leak is...

I should also mention that the compressor was always noisy when first started, back when the a/c worked.

Yep, it sounds like the shaft seal is leaking. Coupled with the noise, I'd say it's done for.
I would suggest a NEW compressor. I know they're pricy but the core stock of R4 compressors is getting pretty ragged these days and the R4 wasn't GMs best effort to begin with. There are some quality remans out there but the price is close to a new unit.
Lower priced Reman R4s are plagued with quality and longevity issues even when the repair is done "right".
Unfortunately, there isn't an easy replacement for an R4 like the Sanden based units made to replace the A6.
Good Luck!

If you are stuck with low funds, you can replace just the seal. For that, it takes a special tool and some knowledge so you might ask your A/C repair shop for a cost. You can also roll the dice and go to a salvage yard and buy an R4 with the plug "Clocked" in the right spot. They will usually guarantee the unit for 30 days and if its going to leak/trash then that is enough time to grenade. However, if it grenades and sends pieces into your system, then you end up replacing the orfice tube, accumulator and flushing the system and all they will do is give you another R4 unit.
Craig

LSRX.....on the subject of A6 versus R4.....I used to look at the A6 (complete with sump) and think "this will cool an Impala in Arizona and they put it on my 2 seat El Camino?" That axial beast was like Prentiss vise......huge...heavy.....and man did they last. However, in the world of style, it was a wonderful thing when the small R4 came out and I could use a CCOT system and not use the POA system like my 1968 truck. I may buy 3 radials to your axial.....but my engine compartment is the "shiznits" and that's what matters down at the A&W.
Craig (too much cold medicine....just ignore me)

Hey thanks for all the help! I'll try to get in there this month and see what the shop says as for cost. I think I'd rather just fix it right the first time and not have to deal with it for a while. I've also read that if I get a new compressor it's good to get a new accumulator(?) It looks like it would be about $225 or so in parts. I'm going to get a new compressor and just spend the extra money when I have it done. Is it unreasonable to buy my own compressor, accumulator (if I need one) and ask the shop to put it in?

Sounds like a plan. Don't forget to have the orifice tube replaced as well.

Depends on the the shop. All of us prefer not to install customer supplied parts, but myself and many others will. I know, especially in this economy, people are pinching pennies just like me. Of course, when I do agree to replace customer supplied parts, I make it very clear that I do not offer any warranty whatsoever.

One more question. Would this be likely to have an expansion valve or an orifice tube?

Orifice tube.

Sweet. Thanks a lot everyone. I'll post back the results when I get time to get the car in and out!

Well I took it in and now it works! The shop charged $300 for refrigerant and installation of a compressor, accumulator, and orfice tube. Unfortunately, a "new" compressor wouldn't fit with the bracket, so I had to use a "remanufactured" compressor. But oh well. I ran it today and it got cold and seemed to cycle regularly. It's hard to tell how it will do in 95 degree heat, but at 60 outside, it froze me out of the cabin. I had jeans and a T Shirt on. The compressor is quieter than my old one. Just out of curiosity, I checked the pressure on the low side service port with the gauge from Wal Mart (I didn't add anything, I just checked it with the gauge) and it read 25 with the compressor engaged. Thanks for all the help everyone, I appreciate it.:You_Rock:

Grats on the freeze!
Do it now and then you don't have to stand in line in July.
I am headed to a friend's shop tomorrow to check my R134. My
gauges are R12 so I need to use his.....and of course he has 240 pounds
of R134 ready for the summer rush. Let's see if lunch at Mickey D's will
get some of that gas in my system......not the gas from McDonalds....the...never mind.
Craig

Yeah, I didn't want to wait for it in the summer. It's a good thing too! It's supposed to be 77 and windy here in Colorado Springs on Thursday. It's a perfect opportunity to see how it does in gentle heat!

I'm glad you're chillin for the summer. Congrats! :beer:
I'm curious as to why the new compressor wouldn't bolt up. As long as the shop used a quality reman though, you should be just fine.

Hey Craig, I hope you got over your cold. :poke: Did you get your AC juiced up?

I drove for many years with no AC and never missed it. As I've gotten older though, AC has moved to the top of my "must have and must work" option list. I must be getting soft.