AC help, what's up?

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Alright guys,

I replaced every O-ring in the system with brand new o-rings.

used a AC system flush, flushed the compressor, condensor, and Evaporator.

Brand new Dryer installed.

Replaced the Mineral oil (R12 specific stuff)

Vac and pressure tested the system,

Filled it with REAL R12. got about 2.5ish cans in the system.

Highside and low side are holding at ~70 psi or so.. (ill have to check the pics i took of the gauges)

Compressor kicks on, ac blue button lights up,


Ac blows Warm air.


i've tried turning the blue knob on the AC controler under the dash.. no change


at this point im a bit stumped.

need something else?

any ideas?

thx
 
What are the pressures when the compressor is engaged? How long does it stay on before cycling off?
 
What are the pressures when the compressor is engaged? How long does it stay on before cycling off?

Thanks for the reply. I just checked the pictures i took of the gauges.

so with the compressor running, i see pressures of 105psi.

when it turns off the hi and lo side equalize at 75psi.

the compessor does not shut off or cycle off. the clutch is engaged, and it just keeps turning.

(unsure if this matters, but in the sightglass of the dryer i can see liquid moving. )
 
Did you replace the expansion valve? I'd say it's either the expansion valve (most likely) or the compressor isn't pumping very well.
 
My A/C isn't as cold as I think it should be...Tell me more about the "blue knob on the AC controler under the dash" please.
 
105 on the high side is way low.. and on the low side it's way too high.

do you have the gauges hooked up right? Separate from each other right?
 
My A/C isn't as cold as I think it should be...Tell me more about the "blue knob on the AC controler under the dash" please.

FAQ can be your friend. You just have to visit, once and awhile.

The A/C Amp Thread
 
On a hot day, the high side should be somewhere between 150-200 psi and low side should be around 35ish psi or lower, but not too low or it will freeze up the system. How much did you actually put in (i.e. pounds, kgs, etc.)? It just sounds like it's either too low on refrigerant or the compressor isn't doing what it should. Static pressures will be around 75ish psi when the compressor is off. What happens to the pressures when the compressor shuts off? Do they slowly go back to static or do they go back fairly quickly? If they go back quickly, that's normal, if they are slow to go back to static pressures, you've got a blockage somewhere. Could be expansion valve, condenser, in one of the lines...but like I said, sounds like it might be a compressor not "compressing".
 
Alright. from the sounds of it I think i likely need a new compressor.

My compressor sat idle for ~ 15 to 20 years and never turned over. Like i said, i flushed it, changed out all the seals, and then refilled with oil. the clutch engages and it spins without noise or any drama.


I did NOT change out the expansion valve because i couldnt figure out how the hell to get to it. i did get the evap cover about 1/2 way off.. im sure there was just one screw or something holding me up.


either way, sounds like im gonna have to sacrifice that spendy R12 i put in, unless someone in the area can reclaim it or recapture it.
 
A shop can reclaim it easily.
 
On a hot day, the high side should be somewhere between 150-200 psi and low side should be around 35ish psi or lower, but not too low or it will freeze up the system. How much did you actually put in (i.e. pounds, kgs, etc.)? It just sounds like it's either too low on refrigerant or the compressor isn't doing what it should. Static pressures will be around 75ish psi when the compressor is off. What happens to the pressures when the compressor shuts off? Do they slowly go back to static or do they go back fairly quickly? If they go back quickly, that's normal, if they are slow to go back to static pressures, you've got a blockage somewhere. Could be expansion valve, condenser, in one of the lines...but like I said, sounds like it might be a compressor not "compressing".


to answer your question, the cans are 12 oz cans, so i put in 2 as best as i could, but it didnt accept all of the second can, so i attached a 3rd and it took about 1/4 to 1/3 of that can. I did my best to get 24oz of R12 in the system.

when things are off, i see 75psi static. when it runs the red gauge goes to zero (high side i believe. upper most attach port on the compressor) and the blue goes to 105.
 
absolutely. That is what the machines are for.
 
right but we're talkin the outlaw R12 here. just to be sure. not 134a
 
And just to be sane here.. should I replace the expansion valve 1st, then fill and test. or compressor first, or..... both?
 
R12 is not really illegal, just expensive.

A shop can do the work for you.

BTW, commonly when the compressors go kaboom, they throw all sorts of particulates into the system. Sometimes you have to replace a lot of things..
 
I would reread post #4 ands go directly to your expansion valve. 1972FJ55 is the absolute authority on a/c's.

John
 
It's illegal to manufacture R12, not to use it or sell it. There isn't anymore being made so that's why it is so expensive now. Get ready for r134a to start to get expensive since they've started implementing the new R-1234yf. It's supposed to take less amount to do the same and also run a much higher pressure. R-134a is supposed to be phased out by 2021.

Anyway, by what you've said about how your pressures are while running, I'll have to agree that it sounds like an expansion valve (or blockage somewhere). Usually if one side is high and one side is real low, there's a blockage in the system. And the smallest point in the system is at the expansion valve. I would check that first.
 
Low pressure on the high side = blockage?
 
I would say expansion valve too just from what you described. How much oil did you put in the system? Too much oil ?
 

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