66 Monaco Wagon A/C Resurrection

Ok, I checked all the mode buttons on high blower, all the servos move correctly and the air flow matches the button selection and is same velocity at all settings. I also checked the heater hoses and can feel one hose hotter than the other although the difference is not dramatic under the hood with a hot engine idling.
Dave, thanks for your help on this. I will also be starting a new thread in the heat / cool / ac forum to see if I get more interest, should be others with similar problems this time of year.
 
I will also be starting a new thread in the heat / cool / ac forum to see if I get more interest, should be others with similar problems this time of year.

Well, silly me, this thread is already in the heat/cool/ac forum!! Has anyone else had similar issues and if so how did you fix them?
 
Well, silly me, this thread is already in the heat/cool/ac forum!! Has anyone else had similar issues and if so how did you fix them?
It sounds to me like the expansion valve could be stuck. Though, I don't know what you could do to test it besides replacement.
 
4 months have gone by and I am no closer to solving my A/C problem, I need some real expert assistance. If you go back to post #72 here you can read about my problem which is that my converted A/C system which worked perfectly for 2 years all of a sudden lost more than half it's cooling power last May. I checked the pressures and tried to add refrigerant with no luck. Everything else works fine, heater is not bleeding into the cooling vents, etc. Today I hooked up the gauges again at an ambient temp of 80 degrees. With the system running the low side read 60psi and the high side was 58. I hooked up a can of R134 and opened the valve, the low side jumped to 90 and the high to 125. I let it run for about 20 minutes, the low went up to 100 and the high did not change, I don't think any refrigerant went in. The chart for 80 degrees ambient says it should read 40-50 low and 175-210 high so it is way off. Has anyone had a similar problem? If so please let me know how you solved it.
 
Have you tried replacing the expansion valve yet? I dealt with A/C this summer as well. The compressor creates the pressure, but the expansion valve causes the drop that separates the two sides. Try taking a temperature gun and measure right before and right after the expansion valve. There should be a temperature drop. Any small particles can get in there and clog it. If you have to replace it anyhow, you might as well give it a few whacks Fonzie style and see if anything changes.
 
Have you tried replacing the expansion valve yet? I dealt with A/C this summer as well. The compressor creates the pressure, but the expansion valve causes the drop that separates the two sides. Try taking a temperature gun and measure right before and right after the expansion valve. There should be a temperature drop. Any small particles can get in there and clog it. If you have to replace it anyhow, you might as well give it a few whacks Fonzie style and see if anything changes.
I haven't replaced anything yet although the expansion valve has been mentioned a few times. I did tap on it gently a few times while I was attempting the charge with no effect. I actually have two expansion valves since I have two evaporators, the front was replaced with the conversion but the rear was not.
 
OK - after many months of lukewarm A/C, multiple hose manifold hookups, requests for help and frustrated confusion - I have apparently solved the problem! As is the case often with me and cars the solution hit me in the face and involved stupidity - and even though the practical results are great the technical results are still confusing.

Cut to the chase - the main reason for the too-high low and too-low high pressures and the failure to accept refrigerant was - wait for it - I forgot that the charge valves at the charge ports loosen and tighten THE OPPOSITE of the manifold valves. So when I thought I was opening a valve I was actually closing it, and vice-versa! A few nights ago I watched about 8 YouTube videos on A/C problem diagnosis and one of them - only one - mentioned this little fact. I pulled out my gauge set and looked, then hit myself in the forehead a number of times.

So today I hooked everything up again, turned the valves the right way and everything was different. Low side started at 10 and high at 125 with system on. Opened the R134 can and it actually went in, can got cold and the vent temps started to drop. It took over an hour but I put in nearly 2 full cans so it must have been quite low on charge. I pulled all the hoses off and took it for a ride - WOW! On a 90 degree day with just the front unit operating I drove for about 20 minutes, starting on max AC and high blower. I quickly froze me up so I dropped down to regular AC and medium blower, still too cold so down to low blower. Even at that setting it was plenty cold, I am pretty sure it cools better now than when I first did the conversion.

So here are the confusing technical results. At a 90 degree ambient temp like I had today, the low pressure should be 45-55 psi and the high should be 250-270. The actual readings on my gauges today were 35 low and 140 high when I stopped the charge. I can't explain it and as long as the system works I don't really care. Thanks to all who commented, I really appreciate it.
 
OK - after many months of lukewarm A/C, multiple hose manifold hookups, requests for help and frustrated confusion - I have apparently solved the problem! As is the case often with me and cars the solution hit me in the face and involved stupidity - and even though the practical results are great the technical results are still confusing.

Cut to the chase - the main reason for the too-high low and too-low high pressures and the failure to accept refrigerant was - wait for it - I forgot that the charge valves at the charge ports loosen and tighten THE OPPOSITE of the manifold valves. So when I thought I was opening a valve I was actually closing it, and vice-versa! A few nights ago I watched about 8 YouTube videos on A/C problem diagnosis and one of them - only one - mentioned this little fact. I pulled out my gauge set and looked, then hit myself in the forehead a number of times.

So today I hooked everything up again, turned the valves the right way and everything was different. Low side started at 10 and high at 125 with system on. Opened the R134 can and it actually went in, can got cold and the vent temps started to drop. It took over an hour but I put in nearly 2 full cans so it must have been quite low on charge. I pulled all the hoses off and took it for a ride - WOW! On a 90 degree day with just the front unit operating I drove for about 20 minutes, starting on max AC and high blower. I quickly froze me up so I dropped down to regular AC and medium blower, still too cold so down to low blower. Even at that setting it was plenty cold, I am pretty sure it cools better now than when I first did the conversion.

So here are the confusing technical results. At a 90 degree ambient temp like I had today, the low pressure should be 45-55 psi and the high should be 250-270. The actual readings on my gauges today were 35 low and 140 high when I stopped the charge. I can't explain it and as long as the system works I don't really care. Thanks to all who commented, I really appreciate it.
Nice recovery!
You had the determination to work through and identify how to charge the system.
Good work!
 
Wow, I didn't look at what my phone thought I wanted to type.

Would the r134 have different pressures than the r12, or should they be the same? Different molecule size, different pressure?
 
Wow, I didn't look at what my phone thought I wanted to type.

Would the r134 have different pressures than the r12, or should they be the same? Different molecule size, different pressure?
I'm sure they would but I have never dealt with R12 on this car. When I got it with the stock system installed it had already been switched to R134. When I did my underhood conversion I used mostly modern parts designed for 134.
 
Thanks, I'll check the hoses, I'm also going to verify all the mode doors are working properly. The rear unit on these cars is always on when the front unit is activated, the only control is fan speed, but yes I had it on full blast. I did replace the filter dryer keeping it in the stock location and adding a pressure switch that was not stock. The sight glass is painted over. There is no obstruction for airflow to the condenser.

View attachment 463550

View attachment 463551
is there a part number or website link for the dryer and sensor?? my original sensor does not match the threads for the new dryer.
 
is there a part number or website link for the dryer and sensor?? my original sensor does not match the threads for the new dryer.
I bought the dryer on ebay, Four seasons 33317. Pretty sure the switch came with it.
 
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