Back in 2012 I converted Old Brickie's Factory A/C to 134A. What I did:

• Flushed system
• New condenser
• New compressor
• New accumulator
• New orifice tube (blue)
• Appropriate PAG oil

I had a vacuum and gauges from HF. I only have Yellow Jacket R12 Gauges.

A/C ran extremely cold (40F 'ish). Ran well for 6 years (low miles annually) but last 2 has not been cold and frankly I did not put gauges on it. So after completing a lot of mechanical work (still lower intake and 3G + Mark VIII fan to do) I need to fix the A/C. It's hot in SC so its jumped to the head of the line.

Today I took a quick look. Gauges read zero so I put the vacuum on for 30 mins. Went to 30Hg vacuum. I stopped the vacuum and it did not hold fully for 5 mins (about 50 pct loss), so I decided to put in 1 can of 134A and a squirt of leak detector.

I did that and started up the truck. The compressor came right on and stayed on. The low side was 90 and the high side 150. I put a squirrel cage fan in front of the radiator. I ran it for 5 mins and saw no change. When I turned it off the low pressure went off the gauge high and the high pressure dropped to about 125. It did not equalize after 15 minutes.

The compressor definitely is noisy & VERY HOT and the accumulator was warm/hot.

So.................what more testing should I do, if any, to pinpoint the issue(s) before concluding I need a rebuild?
If I need a rebuild it seems I should flush, change the compressor, evaporator, accumulator, orifice tube (blue or red?) - anything else? I want cold air and don't want to do it half way.

 

I'd start with a good UV leak detector since it didn't hold. My bet would be the evaporator since we all replace everything else first. I am knee deep in fixing mine too. You are ahead of me.

 

I left the system overnight. After about 20 hours it shows 70 on both gauges. 1 can in system.


Pressures after sitting off overnight



Pressures with 1 can and truck idling. 90 degrees outside. Compressor running continuously.

Input? Also what is involved in changing the evaporator? Still looking for any feedback on Orifice tube blue versus red after conversion.

 

Just tested my gauges. High side won't hold a vacuum when not on the car. Must be an internal leak at the gauge or On/OFF ****. I think I'll go for Yellow Jacket.

 

Obviously, you have a leak. I would shoot in the UV dye and go to town. Look particularly for loose valve cores or fittings. Shaft seal leaks are common as well.

 

there is an HVAC forum on this site. The people there were super helpful on diagnosing and fixing my issue.

 

Thanks - I am getting my gauge situation sorted then I will have a correct baseline & I'll check the A/C Forum. I have shot a dose of leak detector in there but its been a few days. I will be back on it tomorrow.

 

I picked up a set of HF gauges a few weeks back along with a vacuum pump and both worked really good on my 81 F100.

Till you get a set of good gauges its hard to tell anything but if the low side went to 90 from 0 something has to be wrong some place?
I knew my system was empty as it had been open for 4 years, new condenser, dryer, blue orifice valve and 2 new hoses. I am running a junk yard compressor.

I was able to pull a vacuum right a way down to 25 and it held for and hour I them pulled it for another hour+ down to 30HG.
The first 12oz can was added motor off as the vacuum pulled it in. Started the motor to add the next 2 cans and my low side only came up to about 48 if that.
Temp was 100* in the garage, blower fan on high and setting for AC on MAX. I could not get a high side reading as I did not have the adaptor for that side.

It was blowing cool but not cold. After checking charts my low side at that temp should be 50 - 55.
I had to add another 2 cans to get it to 58 psi on the low side, it now blows cold.
Today OAT of 90* I had 51* out of the vent on the right side of the column vent and that was at 45 MPH @ 1300 RPM.

I would say you have a plug some where on the low side but after the low pressure switch as it is keeping the compressor running.
I would have to look over my system to see just how it flows but your a low on high side and a high on low side.
So out of pump > condenser > orifice valve > evap > dryer > pump (red high side / blue low side IIRC)
Dave ----
So what is between the 2 sides? Compressor maybe?

 

The HF gauges and vacuum have served me fine for 8 years. I did 2 R12-R134a conversions. The other is still going fine. I have ordered a set of Yellow Jacket 42006 w/hoses and I already have YJ quick connects. That will put me in good shape going forwards. The HF vacuum is still good.
Yesterday I used a YJ R12 set I have to pull a vacuum and determined that I do have a significant leak. There was no pressure at all to begin with so it was clear I did. But I lost 30Hg quickly. Might be anywhere. Not obvious
I have decided that I am going to do a complete rebuild and am going to wait until October. I can grind through till then.

I suspect you are also right about a blockage. My suspicion is the compressor has gone bad too.

I would like to get comments on compressors for sure. The one I used in 2012 was a Four Seasons 58120

 

Four Seasons was always a good name in AC parts.
I just could not swing the $$ from the banker (wife) for a new compressor so went with the JY one and so far so good.

I don't know AC systems all that well but I would say the compressor is bad also.
If you pull the orifice valve it should tell you if the system has junk floating around in it.
If it does have junk I would replace everything to be safe as I don't think you could flush it all out.
Good luck and keep us posted what you do.
Dave ----

 

I am going to pull the orifice tube. Either way I've decided to do a complete rebuild as my truck will likely be here when I've gone