Who's Good With The Old GM Cars-A/C Realted Problem!

[Ghettoboom767]

Hi guys-I'm having some problems getting my compressor to stay on on my Z-28.
I just converted it to the new Freeze 12 and I can't get the compressor to stay on or go on by itself!
I did manage to get both 12oz. can in-on the 2nd. can I ran a hot positive wire to the a/c wires going into the compressor then it stays on.
Here's the deal-there is 12 volts going to the switch but when I connect it to the compressor-nothing! There is no voltage and the compressor doesn't kick in.
I'm thinking it might be a bad relay or something-it's blowing pretty cold air now but again I have to hook up a positive lead to the compressor.It has 2 12oz cans in it right now-only probably about a 1/2 can low now but is blowing cold when the compressor is on!
Any ideas guys-I don't want to take this in as I'm short on $ right now and I thinki t's something I may be able to fix.
Fuses look good to as again there is power going to the compressor-hook it up-no voltage!
Where to look next-is there a relay and I wonder I may have to bring it in if I can't figure it out in a week.
BTW-It's a 1981' Camaro Z-28 with the Frigidaire system.Holding freon to!
Any help would be greatly appreciated-GB.

 

[oldskool69]

It sounds like the relay. Have you tried replacing it yet?

 

[Ghettoboom767]

It sounds like the relay. Have you tried replacing it yet?

Hi Freddie-I have to remember where it is!
I think it's on the a/c housing where all the wires go into the big plastic thing where the big evaporater is.
Thanks and I'll be working on this some more tomorrow-It's so damn hot and humid out today-wow!
It does blow prety cold air when the compressor is going and that's good!!
Thanks-GB.

 

[Fatdog]

Does your Camaro have a low-pressure cut-off switch? It should be located on the accumulator or the low-pressure line close to the accumulator.

If you have one, unplug the electrical connector. Jump across the two terminals and try the A/C. If it works the switch is bad.

It could also be a ground problem.

 

[turbomustang84]

is the AC clutch coming on ? if not that could be your issue

 

[Ghettoboom767]

The clutch works but only when you run a hot positive lead to it.
Otherwise It doesn't come on like it used to(by itself) and then it was going on & off all the time! even earlier this spring.
That could be it if the clutch is burned out(it's internal).the wiring at least.
I'll have to look into this further.
Thanks guys-GB.

 

[monchito]

make sure you have the correct amount of freon or the low pressure switch will not let the compressor stay on ,, it needs the right amount

 

[Ghettoboom767]

make sure you have the correct amount of freon or the low pressure switch will not let the compressor stay on ,, it needs the right amount

Good point and I do know this but after 2 -12oz cans and the fact that it's blowing fairly cold air means that it must be something else.That's 22-24 oz. and i believe the thing holds 3 1/2 lbs.42 oz.-I'll look again-Should kick in by now though.
I also don't think it would be the clutch becasue the fact is if you wire the positive from the battery directly to the wires going into the compressor it goes on and stays on.
So the clutch works but it may be the relay that turns it on?
It's again funny because like I say there is 12 volts at the wiring clip that goes onto the compressor but as soon as you hook it up there is no voltage.
There is a little resistor that goes across the 2 leads but this I'm not sure is working.
If I jump across that still nothing-No voltage as soon as I connect it-wierd.
I'm thinking a relay or the little resistor or both.
I'll take photos tomorrow and talk to 2 mechanics.
Thanks guys-GB.

 

[monchito]

ok make sure you check the switch in the dash by the looks you may have a broken wire somewhere relay or a fusible link you have to trace all that

 

[Ghettoboom767]

ok make sure you check the switch in the dash by the looks you may have a broken wire somewhere relay or a fusible link you have to trace all that

Hi Ramon-Yes I know that switch works because the fast idle dashpot acctuator engages for high-idle when in a/c position also the air does blow cold when you wire directly to the compressor and it kicks in alittle higher(fan speed) when you go to the max position.
That's all ok.
I'll let you know more tomorrow night.
Thanks again-Jeff.

 

[Superduper]

make sure you have the correct amount of freon or the low pressure switch will not let the compressor stay on ,, it needs the right amount

The amount of freon is extremely important. Too little and the compressor will not run. Too much and you could be setting yourself up for problems. Just because it blows cold when you hot wire it doens't mean it was done correctly. The correct way of doing this is the evacuate the system first with a vacuum pump, then slowly fill in the correct amount of freon. After evacuation, you'll know that there is nothing there. When you fill, you can fill the exact prescribed amount for your particular car. Also, putting in freon without measuring pressure is WRONG. You need a guage set to hook into the low and high side. The A/C system has many safety devices to ensure proper operation. Hooking up the wire directly merely bypasses them all.

Finally, there is nothing wrong with the A/C clutch if you hot wire the clutch and it blows cold air. If the clutch was slipping or inoperative, you won't be able to get it to work just by hard wiring it. Sorry I can't offer you a simple answer but there is only 1 right way to diagnose this and the first step is to make sure that you have the proper amount of freon and (2) make sure that the operating pressures are within specifications.

 

[Ghettoboom767]

Hi SD-I agree with you there-I'll put the exact amount in with a gauge.
It was all empty because I had to replace the fitting and thus remove the air valve.I don't have anything to evacuate but it was empty and again is blowing somewhat cold air-I can tell it's not full,2 full 12 oz. cans for 24 oz so far that I know.
I'll be doing this later this week-I have to buy another can.
Thanks again-GB.

 

[Superduper]

Hi SD-I agree with you there-I'll put the exact amount in with a gauge.
It was all empty because I had to replace the fitting and thus remove the air valve.I don't have anything to evacuate but it was empty and again is blowing somewhat cold air-I can tell it's not full,2 full 12 oz. cans for 24 oz so far that I know.
I'll be doing this later this week-I have to buy another can.
Thanks again-GB.

Well, you probably already know this but the reason you evacuate the system is because:

(1) you want to start with nothing in the system and the only way to get rid of everything is to evacuate. By replacing a fitting, you've ensured that the system is no longer pressurized but there is still something in the system including oxygen. What you want is pure freon only.
(2) moisture is a terrible enemy of the A/C system. The only way to get rid of all the moisture is to evacuate the system. The tiniest spec of foreign material or moisture in the system could cause problems later on due to corrossion and cloggin of the expansion valve.

Question: Since you've replaced a fitting, are you retrofitting the system to the newer refrigerants? They aren't really compatible and isn't R-12 no longer available due to it's supposedly damaging effects on the ozone layer? If you are using the newer refrigerants, they really aren't compatible and you really should evacuate the system. Perhaps you could rent a vacuum pump at your local auto parts store.

 

[Ghettoboom767]

There's a new thing out called Freeze 12 for R-12 systems.Got it NAPA
It has better cooling charachteristic properties than the R-134.
If I had a vacumn or could evacuate I would.
It still works just need to put 1 more can in and check the level and then check the relay for current.
I'm doing this by this coming weekend.
I've been filling cars a/c systems for decades-I know this but $ is a factor sometimes.
Have a good one-GB.

 

[monchito]

gb did you replace at least the drier everytime you open up a system or fix a leak its always good to replace that drier

 

[Superduper]

Hey GB, can you show us a picture of your Z? I used to have one, loved it to death, totally rebuilt it including installing the hottest engine at the time -- GM ZZZ HO crate engine. Unfortunately, the insurance company totaled the car when it was stripped of T-Tops and other parts. They said the T-Tops were worth more than the car. :'-(

So, I bought the car back for sentimental reasons and kept my engine (200 miles on it) and still have a set of those orig rims -- so pretty.

 

[Ghettoboom767]

HI SD-It's on this forum-just go to like page 2 or 3.
It still needs some body work and a paint-job but it really runs great!
I could take it anywhere right now.Mechanically everthing is rebuilt except the rear pumpkin.Tons of new stuff in her(front-end parts-ball joints,rebuilt tranny & motor with only approx 62,000 on both.
Just want to get the a/c finished and put in a cap-rotor.Did everything else last fall-haven't driven but a 100 miles this year.
Got to get some work done this fall later.
All new pumps and belts an all that last fall to.Did it all myself.
Thanks-GB.

 

[majestic]

GB......The best thing to do is head to you local library. There they have some Chilton manuals that you look in for most years. It should give you the Spec's for the total system capacity. You can pick up a Chilton for around $20.00 new

SD is a 100% right in that you really do not want to guess at how much you have in the system . You wont get too far. If you overcharge the system then your best bet is that the pressure relief valve works as intended and you only crap your pants when it "Farts" real loud. Then you will truly know it's overcharged.

Too add to what SD stated on vacuuming the system, the biggest factor is that you will boil out the moisture within a negative pressure.

Worst case scenario. You blow a line off. The you will have incurred more cost's than originally intended. At this point if your were to bring in to me to look at it the only way to properly diagnose and repair it would be to put the manifold gauge set on it and see if it related to improper charge amounts or truly electrical based.

If your using a DVOM to measure the 12v at the clutch connector and it goes away when plugged in then the circuit consumed all of the 12V when the clutch applied. This is usually a sign of a failed connection or failed switch at the supplied circuit or somewhere in the wiring harness. If you do not have a wiring diagram then you have to manually trace out the circuit. You confirmed this when you applied 12v straight to the A/C clutch.

What you see at the A/C compressor connector is a one way diode. No resistor.

Now given you stated it takes about 42.oz then the cycle switch most likely will not come on at half a charge.
In 81 the low cycle switches were not that great. So it needed almost a full charge before it would come on. Now if you had a full charge then I would blame the low Cycle switch. As a matter of fact the loss of the voltage when the clutch is plugged in is a sure sign that the switch has failed to carry the load (12V).

 

[Ghettoboom767]

GB......The best thing to do is head to you local library. There they have some Chilton manuals that you look in for most years. It should give you the Spec's for the total system capacity. You can pick up a Chilton for around $20.00 new

SD is a 100% right in that you really do not want to guess at how much you have in the system . You wont get too far. If you overcharge the system then your best bet is that the pressure relief valve works as intended and you only crap your pants when it "Farts" real loud. Then you will truly know it's overcharged.

Too add to what SD stated on vacuuming the system, the biggest factor is that you will boil out the moisture within a negative pressure.

Worst case scenario. You blow a line off. The you will have incurred more cost's than originally intended. At this point if your were to bring in to me to look at it the only way to properly diagnose and repair it would be to put the manifold gauge set on it and see if it related to improper charge amounts or truly electrical based.

If your using a DVOM to measure the 12v at the clutch connector and it goes away when plugged in then the circuit consumed all of the 12V when the clutch applied. This is usually a sign of a failed connection or failed switch at the supplied circuit or somewhere in the wiring harness. If you do not have a wiring diagram then you have to manually trace out the circuit. You confirmed this when you applied 12v straight to the A/C clutch.

What you see at the A/C compressor connector is a one way diode. No resistor.

Now given you stated it takes about 42.oz then the cycle switch most likely will not come on at half a charge.
In 81 the low cycle switches were not that great. So it needed almost a full charge before it would come on. Now if you had a full charge then I would blame the low Cycle switch. As a matter of fact the loss of the voltage when the clutch is plugged in is a sure sign that the switch has failed to carry the load (12V).

Thank-You Majestic-I think you've confirmed a couple of things I was thinking.
I have a friend that's a mechanic and I'm going to have him put his gauges on it and fill it all the way up and I'm going to evacuate it to.
I'll let you know when it get's done.
I appreciate your help-GB.