1966 Dodge Monaco Wagon A/C Resurrection

[TexRiv_63]

12 hours ago, Bill Stoneberg said:

Buick’s from the 60s also use two belts to prevent squealing and slipping.

 

Don, have you put a thermometer in your vent to see what the temp is ? 

The thermometer I have doesn't really work but I know the cooling output is probably half what it was before. Really need some expert help here as I don't want to tear this thing down unless I have to.

[TexRiv_63]

4 months have gone by and I am no closer to solving my A/C problem, I need some real expert assistance here. My problem continues to be 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. Everything else works fine, heater is not bleeding into the cooling vents, etc. Today I hooked up the gauges again for a second try 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, similar to my last try. 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.

[Ben Bruce aka First Born]

I think the compressor has taken a dump.  

 

  Ben

[TexRiv_63]

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.

[avgwarhawk]

Nice job on the installation.  Looks great and part of engine(not a add on) 

[Oldtech]

On 9/28/2021 at 3:04 PM, TexRiv_63 said:

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.

It's called live and learn. I thought a compressor was dead once. finally discovered valves on gage set were all open. . 🤔