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My 1970 Sedan DeVille. I can't get my AC to cool the car.

Started by stushug, October 11, 2021, 03:38:16 PM

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"Cadillac Kid" Greg Surfas 15364

Short of refrigerant. What is the outdoor temp?
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

stushug

Approx 83 ambient temp. Did you notice the tiny bit of moisture on the edge of the sight glass? Is it my imagination or something to watch? I didn't see it live, but noticed it at the very beginning of the video I uploaded.

Cadman-iac

  Greg, correct me if I'm wrong, but doesn't an R134A compatible synthetic oil work much better than regular pag oil, especially in a retrofitted system?
 This has been my experience anyway. I've had 2 different compressors go out not long after the conversion, but when I switched to the synthetic oil I haven't had any further problems with either one, or any of the ones I've done since.
 Since you have been involved with air conditioning for years, I figured you might know why.
  Thanks, Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

stushug

I added more 134, stopped at about 36psi. Temp out of the vents is now 58, still not enough to cool the car, but better.

"Cadillac Kid" Greg Surfas 15364

Take it out on the road at a steady 60 for a few miles and see what it does. With 134a and slow engine speed the performance is by far inferior to R-12
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

stushug

Took the car out today. When I started, the ambient temp was about 64. The temp out of the vents was 48. Drove on the highway to a friend's house. By the time I arrived, the ambient was still only about 66 but the temp out of the vents had risen to 70. About an hour later, I left to return home. Ambient about 72, temp out of the vents was back down to about 48. It stayed there until I got home.  It only went to mid 40's once before, that was when the shop first charged the system last year. It only stayed there for a few minutes that day, and never got that cold again until today. I don't know what to make of this, so I'll just drive the car around a few days and see what happens.

stushug

Used the car yesterday, air out of the vents was a "frigid" 92 degrees. Extremely disappointing. Today I checked with my gauges and I have 19lbs on the low side and 38lbs on the high side, and I can see almost no flow through the sight glass. Even with my limited knowledge, I'm thinking I have a leak. When the system was charged, the tech did whatever process he does to verify there were no leaks after he installed the new hoses I had made for the car. It checked ok or he wouldn't have charged the system, at least that what he told me. He's been doing this for over 30 years and assured me he is very familiar with the system on my car. I've thrown a ton of questions at him to test his knowledge and he was able to answer them.
What would be the next logical step?

V63

It's simply going to need more leak investigation , one place often overlooked  is the charging ports! After you remove gauge set wet your finger and hold over the port for a few minutes and see if it pressurizes under your finger. Or drip refrigeration oil and fill the port...then look for a bubble

"Cadillac Kid" Greg Surfas 15364

Another issue aside from the low refrigerant might very well be residual mineral oil left in the system when R-134a was added turning to sludge and clogging up the system
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

stushug

Quote from: "Cadillac Kid" Greg Surfas 15364 on May 23, 2023, 02:02:43 PMAnother issue aside from the low refrigerant might very well be residual mineral oil left in the system when R-134a was added turning to sludge and clogging up the system
Greg Surfas
If that's the case, what is the remedy? I've ordered a sniffer and some dye to check for leaks first. The part that puzzles me is everything that carries refrigerant is brand new, so there shouldn't be any leaks. The only item not replaced or rebuilt is the evaporator. I'm starting to think the problem may be there.

"Cadillac Kid" Greg Surfas 15364

First step:find the leak and fix it. 
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

stushug

I put my manifold gauges and there was virtually no reading, so I assumed all the 134 was out. I vacuumed down the system to 30Hg. It held for about 15 minutes so I know there is a leak. I added some dye and some refrigerant to circulate it. Ran the car for about 15 minutes and noticed that the lower half of the POA valve was frosted over and so was the end of the hose connected to the back of the compressor. They didn't stay that way very long. Went off to take care of some other things, came back about 90 minutes later and ran the car again. This time, the lower tube from the evaporator that connects to the bottom of the expansion valve was iced up (pictures below), but that was the only cold spot. Air out of the vents was about 80 degrees, ambient was also about 78. I'm going to wait till it gets dark to see if any dye shows up so hopefully I can find the leak(s).

stushug

I waited for it to get dark, and I just checked the car. There is no dye visible anywhere. I can see it flowing through the sight glass so I know it's making its way through the system. I know it didn't hold vacuum so there must be a leak. The only thing I can't check readily is the evaporator because it's inside the case on the firewall. What is the simplest way to access the evaporator to see if it is leaking?

"Cadillac Kid" Greg Surfas 15364

With an electronic (or Halide) leak detector.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

stushug

Is this one a good one? I just received it yesterday. I think I have to open the evaporator case to insert the working end of the detector, right?

Pghcc2006


stushug

No. Judging from the last testing I did, I think the evaporator is the problem and I haven't had the desire to take the whole firewall apart to get to it.

"Cadillac Kid" Greg Surfas 15364

If there is refrigerant in the system and there is a refrigerant leak in the evaporator the leak detector will pick it up by putting the probe into the right side dash vent
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

stushug

Quote from: "Cadillac Kid" Greg Surfas 15364 on August 01, 2023, 10:27:38 PMIf there is refrigerant in the system and there is a refrigerant leak in the evaporator the leak detector will pick it up by putting the probe into the right side dash vent
Greg Surfas
Thanks, Greg. Unfortunately, the last thing I did was vacuum down the system, so there's no 134 in there now. I guess I could add some and run the test you suggested though.