Help! 1981 AC problem

[Granpooba]

Hey Fellows,

Have an AC problem on my 1981. Took it for a ride yesterday and all the AC did was blow hot air. Started it up this morning, turned on the AC and out came beautiful cold air. That is, cold air for a minute or two, then you can hear the compressor kick out and out comes the hot air.

Not really familiar with all the components in the AC system, but something in the back of my head is telling me that I may have a bad AC compressor. Also at times, it makes a slight noise like its not lubricated or a rattling inside of it.

Looking for any and all opinions.

Thanks ..............

 

[n8dogg]

low on freon

 

[Granpooba]

low on freon

Low on freon ? But I just serviced it ! Wondering if I serviced it with enough ? What do you think ?

 

[Granpooba]

Just wanted to add that this problem keeps repeating itself. Start driving car, turn on the AC and it blows cold air, for a short time. Then the AC kicks off and naturally it then blows hot air.

Do you still think this problem could be related to low freon ?

 

[TimAT]

IF your compressor is rattling it may be on the way out. The R4 comressors usually sound off before and as they die. They do all tick a little bit but if it's rattling very bad- it's not good. You might be able to add some oil and have it checked to make sure it's full of freon.

YOu said it cycled out pretty quick- that's a good sign of low freon. When it's running, the suction side drops and if the low pressure passes the set point of the cycle switch it shuts it off.

 

[Granpooba]

Friend of mine just brought over a guage to check freon capacity. Will probably do that tomorrow. I am sure that it was low. Added one small can of freon, but now wondering if that was enough to completely service the system.

 

[Dunzvett81]

99% sure it is your compressor. Mine did same thing. put a new one on and cold air again (all the time)! good luck and welcome to CAC.

 

[bill81vette]

IF you need I can give you the name of a fellow in Saratoga who did mine last year!!!!
FYI These systems hold about 3 lbs....

 

[Granpooba]

IF you need I can give you the name of a fellow in Saratoga who did mine last year!!!!
FYI These systems hold about 3 lbs....

I'm going to try adding more freon over the next couple of days. If that does not solve the problem, I may very well ask you for the fellows name in Saratoga.

I know that I would not take it to the local Chevrolet dealer for this fix. The compressor failed on my TrailBlazer and they wanted $800.00 to replace it.
Had a local AC shop repair it with exactly the same parts that would come from GM, for $500.00. Big difference if you ask me and that is $300.00 in my pocket.

 

[Yoda]

When I bought RARE the air conditioner worked somewhat.

I found a shop that knew air conditioning and would still use the R12, not the Mexican or fake contaminated R12. Small explaination... the shop I took it too had a recovery device for the R12 and would only work on the air in RARE if they could test the freon and do a complete service on it.

The complete service was to evac all the old R12 then they pulled vacuum on the system for what seemed like for ever, probably an hour Checked for leaks found one small one on a hose fitting :eek then they filled the system with fresh R12 and added somekind of oil along with the filling process.

That was 1999 and RARE has been working great since.

The R12 is really hard to find, at least the REAL R12. I have been thinking about converting over to the new stuff, but so long as the air conditioning is working I ain't messing with it

Good Luck

Bud

 

[bill81vette]

Mine was converted last year.
it isn't R-12 but it is cooler than nothing!!!

 

[Granpooba]

Not low on freon !
Put a guage on it and it shows full. Actually slightly into the overfill zone.
Any more ideas ?

 

[73shark]

At what pressure on the low side was the compressor turning off? Same question for the high side.

 

[gmjunkie]

Not low on freon !
Put a guage on it and it shows full. Actually slightly into the overfill zone.
Any more ideas ?

Yeah,I have allot of Ideas! :L
But you probly won't like'em!!:L
I need more information!!
Are we using Real R-12??
Are we using Johnsen's Freeze-12??
And what kind of Pressures are we running,High Side /Low Side??
(When the compressor is running!)
What is the Humidity??
What is the Ambient Temp??
What is the Engine Coolant Temp??
Are all the Air Deflectors in place around the Radiator and Condenser??
Is your Radiator and Condenser free of deb're??
Is the Evaporator free of Lint,Leaves,Mouse Nests,or other obstructions??
What is the AC Discharge Air Temp when it runs before it go's Hot??
What is the Low Side pressure when the Compressor shuts down??
What is the High Side pressure when the compressor shuts down??

 

[geekinavette]

What is the Low Side pressure when the Compressor shuts down??
What is the High Side pressure when the compressor shuts down??

Those two are exactly what I'm wondering too...

Say for argument's sake the charge is low...obviously it is charged enough to trip the low pressure switch and allow the compressor to engage. If the system is undercharged, then the low side pressure drops below the switch threshold (somewhere around 20-30psi), compressor shuts off. Once the compressor shuts off, the low/high side pressures begin to equalize again, and since there was enough charge to turn the compressor on in the first place, the system should equalize to the point where the switch closes again (high side drops, low side rises), compressor turns on, high side pressure increases, low side pressure decreases...and the cycle repeats.

No, this is not just a simple matter of being undercharged. Maybe it is and a switch is sticking....hard to say. Maybe its overcharged and the high side switch is opening and sticking. Maybe the orifice tube is clogged and the high/low side pressure differential is not equalizing when the compressor turns off. There are so many possibilities. Really the high and low side pressures need to be known, otherwise it's just guessing and speculation.

 

[gmjunkie]

Yeah,I have allot of Ideas! :L
But you probly won't like'em!!:L

No, this is not just a simple matter of being undercharged. Maybe it is and a switch is sticking....hard to say. Maybe its overcharged and the high side switch is opening and sticking. Maybe the orifice tube is clogged and the high/low side pressure differential is not equalizing when the compressor turns off. There are so many possibilities. Really the high and low side pressures need to be known, otherwise it's just guessing and speculation.

Thats exactly what I'm thinking!!My guess is the Accumulator Drier has came apart,letting desiccant circulate and clogged up the works!!:W:W:W

I think I said something about he probly wouldn't like my Ideas!!:L:L:L

 

[geekinavette]

Thats exactly what I'm thinking!!My guess is the Accumulator Drier has came apart,letting desiccant circulate and clogged up the works!!:W:W:W

That would definitely clog up the orifice tube wouldn't it! A severe restriction could explain the compressor shutting off and staying off for a long time (eventually it would turn back on again, but it could take a LONG time)....as well as explain the noisy compressor by blocking the refrigerant/oil charge from reaching the compressor.

At the very least a gauge on the low side would show this...if the pressure does not climb when the compressor shuts off then there is definitely a restriction.

Hmmmm....

 

[73shark]

I was wondering what kind of gauge he was using that indicating the charge level.

 

[Mr. Chuck]

If you live SoCal, they passed a law that the cans of R12 are no longer legal and you are stuck with going to a A/C shop where you either conver to the new coolant, i.e. which means converting the system with compatable seals, etc. The shops here are also required to drain / capture system coolant as to not pollute the environment.
The heavier oil they add lubricates the compressor and doesn't mix with the freon which rides on the oil surface. Beware if the A/C plumbing becomes open to the atmosphere for an extend period of time, you can loose the freon / oil and the compressor runs dry, it starts making metal and/or the system gets contaminated and you have major service issues / cost.
I removed the drive belt from the compressor, no point in using horsepower to drive a dead horse, I also un-pluged the electrical connector at the compressor.

 

[gmjunkie]

That would definitely clog up the orifice tube wouldn't it! A severe restriction could explain the compressor shutting off and staying off for a long time (eventually it would turn back on again, but it could take a LONG time)....as well as explain the noisy compressor by blocking the refrigerant/oil charge from reaching the compressor.

At the very least a gauge on the low side would show this...if the pressure does not climb when the compressor shuts off then there is definitely a restriction.

Hmmmm....

Exactly!!The big boys down at the pool hall say 5-6 years life expectancy on a drier,after that your on borrowed time!!Some have made it 30 years though if the system is kept up properly,but realistically most don't make it but about 8-10 and a complete rebuild is due!!