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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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bctexas

Quote from: V63 on October 15, 2021, 01:57:12 PM
I just shopped for a unit that looked like this, the Cadillac clutch and belt spacing is unique and despite ordering one for a Cadillac I always get the Chevrolet . I do not believe they offer one for Cadillac. So the compressor mounting needs to be fabricated to align the belts. I sourced mine from a local auto parts chain.

Were you able to find one with a two groove pulley?  As little wrap as the belts have around the ac compressor, I didn't think a single belt would work.

Thanks!
1965 CDV
1970 SDV

V63

Other years used a single belt?  in fact all those after 1970? So long as you can get pully belt alignment.

For what it's worth, I do have a rebuilt double groove compressor that I could part with. Never installed but it passes my  'will it turn' test out of the box... that amazingly most will not pass that simple test. And I mean they will NOT turn with two hands and pulling a face will not turn!

Scot Minesinger

dual groove a/c clutch belts were used from 1968 thru 1972, and they worked great.  Someone brought me a 1969 Cadillac with a single groove on the power steering pulley and the belt would not stop slipping until I changed to a two grove.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

chrisntam

IIRC, the dual belt set up used narrower belts, 15/32"s, the single groove compressor may have used 17/32" wide(r) belt.
1970 Deville Convertible 
Dallas, Texas

35-709

My '73 Caribou had dual A/C belts, still does --- single belt may have been a mid-year change when they went to HEI.
The Pro6ten and S6 aftermarket compressors that replace the A6 do not draw as much horsepower as the A6 and seem to be fine with a single belt.  I like my S6 on Big Red's '71 472 which is converted to a single belt and HEI.
The S6 is available from Original Air and also from Classic Auto Air, the Pro6ten is available from Old Air Products.

Yes, the dual belt system used slightly narrower belts, but using an aftermarket replacement compressor as described above, the narrower belt in a single configuration works fine (for me here in FLA). 
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

V63

Quote from: 35-709 on October 15, 2021, 08:19:12 PM
My '73 Caribou had dual A/C belts, still does --- single belt may have been a mid-year change when they went to HEI.
The Pro6ten and S6 aftermarket compressors that replace the A6 do not draw as much horsepower as the A6 and seem to be fine with a single belt.  I like my S6 on Big Red's '71 472 which is converted to a single belt and HEI.
The S6 is available from Original Air and also from Classic Auto Air, the Pro6ten is available from Old Air Products.

Yes, the dual belt system used slightly narrower belts, but using an aftermarket replacement compressor as described above, the narrower belt in a single configuration works fine (for me here in FLA).

Amen!

The Tassie Devil(le)

On my '72, I have a different setup where the AC Pulley is a single groove, and I use front belt to drive the AC, Power Steering, and back to the crank, and a shorter belt to drive straight to the Power Steering.

Sometimes there is the slightest of slippage at start up, but then all good.   

The reason I haven't converted the AC to the double-groove pulley is that I don't want any interference on the side of the HEI Distributor cap, which sometimes happens with the dual belts.   It works, so why change it.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

V63


The Tassie Devil(le)

The main thing is to keep the single belt in good condition, as the single belt, from the matched pair duals is of a narrower cross section than the normal single belt.

This causes the narrower belt to sit lower in the pully "wedge", and too much wearing of the belt will result in the bottom of the belt riding on the bottom of the groove, thereby slipping as it loses friction of the sides.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

stushug

I removed the heater box, made sure the heater core and evaporator coil were clean. Then I re-foamed the purge door. There were NONE of the original seals left. The firewall gasket was in almost perfect shape so I re-used it when re-installing the heater box. Now that the purge door seals when closed, the temp out of the AC vents was about 52 while driving with an ambient temperature of 69 degrees. That's a gain of about -5 degrees from where it was before I re-did the heater box. Next I will order the parallel flow condenser that chrisntam said that Scot installed in his car.

chrisntam

Quote from: stushug on October 19, 2021, 03:50:13 PM
... Next I will order the parallel flow condenser that chrisntam said that Scot installed in his car.

Twern't me, I think it was BCTEXAS.

But congrats on getting the heater box out and back in.

chris.
1970 Deville Convertible 
Dallas, Texas

stushug

You're right, it was BCTEXAS. You had quoted him in a later post and I took my info from there.

Big Fins

On my '69, it has a replacement A-6 of the R-12 variety, the original POA and expansion valve, the original condenser and it has been converted to R134-a prior to my ownership. I evacuated the system, added 2oz of oil and installed 4, 12oz cans of R134-a refrigerant. It operates as it was intended from the factory with a 45o vent temperature on an 83o Florida day with 60% humidity.
Current:
1976 Eldorado Convertible in Crystal Blue FireMist with white interior and top. (Misty Blue)
1969 Fleetwood Brougham in Chalice Gold FireMist with matching interior and top. (The Old Man) SOLD!

Past and much missed:
1977 Brougham de Elegance
1976 Eldorado Convertible
1972 Fleetwood Brougham
1971 Sedan de Ville
1970 de Ville Convertible
1969 Sedan de Ville
1959 Sedan deVille

stushug

I took the car to the AC shop today to have them evacuate the system so I could install my new condenser. I sat down in the waiting area and within two minutes the tech came in and said we have a problem. Seems the car wouldn't start, the battery was dead. Well it's a new battery and a new alternator so I said IMPOSSIBLE! As it turned out, I have a replacement end on the positive cable that just clamps down on the old existing wire and when we opened it up it was full of corrosion. A little work with a wire brush and the wire wheel and all was good again. I ordered a new cable from Caddy Daddy as soon as I got home. While I was doing that, the tech was emptying the system. I told him I was going to install the new condenser as soon as I got home. He told me he won't be able to fit me in till Monday or Tuesday for a recharge so I'll have to wait until then. The swap was relatively painless, the only issue was the holes for the mounting tabs on the new condenser had to be elongated to fit the original mounts. Everything else was extremely easy. When disconnecting the old condenser, I found the o-ring for the upper hose was pretty misshapened. No wonder I  trust only myself to do my own work. The new condenser has 38 cooling tubes where the original had 18, so I'm expecting better performance, but I won't find out until next week. I'll post results. I'm putting up some pics for your visual enjoyment!

Note: These condensers come painted silver, I sprayed it black so it would'nt show so much through the grill.

"Cadillac Kid" Greg Surfas 15364

Just a note here.  The single tube "serpentine" condenser was determined to be far superior in the area of oil control/return, and was sized to handle ALL the hot gas refrigerant the compressor was capable of producing and provide the requisite amount of sub cooling.
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-

chrisntam

Quote from: "Cadillac Kid"  Greg Surfas 15364 on October 27, 2021, 08:23:22 PM
Just a note here.  The single tube "serpentine" condenser was determined to be far superior in the area of oil control/return, and was sized to handle ALL the hot gas refrigerant the compressor was capable of producing and provide the requisite amount of sub cooling.
Greg Surfas

All right Greg...dumb the above statement down about 4 notches so us regular folks can understand.  What will that mean for the system performance?

:)
1970 Deville Convertible 
Dallas, Texas

"Cadillac Kid" Greg Surfas 15364

I didn't want to get into too much detail unless someone asked and you did, thanks Chris. With one continuous tube any oil that is discharged from the compressor (normal operation) is carried along with the hot gas and then the condensing liquid refrigerant. It (the oil) has no place else to go and by keeping the velocity up oil entrainment (oil that is mixed with the refrigerant) is enhanced.  This is much more important when the load is light and refrigerant flow is reduced. Oil return in all types of refrigeration is dependent upon maintaining hot gas velocity.
Also, with the higher pressure drop, the compressor has to generate more pressure so that again at light loads especially, the discharge pressure will be high enough so that the refrigerant will condense at what ever ambient temperature the condenser sees. Yes, low (too low) head pressure will reduce the system capacity, just feeding a mixture of liquid and vapor to the expansion valve. Not good.
With the parallel flow condenser, there is no question that the hot discharge gas is slowed down and the heat transfer surface area is increased, but under many conditions for the reasons described above this is not an advantage.
It all has to do with the actual fluid flow and thermodynamic characteristics of a refrigeration system, many of which are in contradiction to what would seem appropriate in terms of combustion engine characteristics.
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

Hey Greg,
I just read your posts. I appreciate your input, thanks for the info. Does that mean that the new condenser I installed is a plus or a minus for my system?
Stu

"Cadillac Kid" Greg Surfas 15364

Mixed bag. PERHAPS a small increase in capacity AT FULL LOAD ON THE SUMMERTIME TRAFFIC but reduction of velocity will inhibit oil return at less than full load leading to premature wear due to lack of oil circulation. As fa as your car is concerned, what is the result of this change?
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 October 28, 2021, 03:59:08 PM
Mixed bag. PERHAPS a small increase in capacity AT FULL LOAD ON THE SUMMERTIME TRAFFIC but reduction of velocity will inhibit oil return at less than full load leading to premature wear due to lack of oil circulation. As fa as your car is concerned, what is the result of this change?
Greg Surfas
I won't know until next week when it gets recharged. I'm not sure what the weather is going to be like, but I think we'll probably have highs of 55 here in Pittsburgh. I probably won't know for sure until next spring.