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1969 CAD LIMO REAR A/C

Started by 1969cadillac, October 11, 2016, 09:00:16 PM

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1969cadillac

Hello , I am wondering what to do about the rear A/C on my 75 series limo , which has probably not worked for years .

I am restoring the car chassis and mechanical

I wonder if it would be best to disconnect the rear A/C from the front unit , therefore not using the long A/C pipes that run to the rear unit.

I was thinking of using an electric compressor to run the rear unit only and mount a seperate condenser for the rear unit only , but where ?

Murray Mules 

cadillacmike68

The rear system has its own condenser and evaporator, it is only missing the compressor. However, fitting something in with auto temp control will be a serious PITA at best.

The existing system is not that much more complicated than the single system. There is a second control unit and some vacuum lines, but the rest of the system just piggybacks off the main system.
Regards,
"Cadillac" Mike

"Cadillac Kid" Greg Surfas 15364

Murray,
My suggestion would be to restore the complete system,
Front and rear. Both systems utilize the single compressor and condenser. The rear system consists of a blower/evaporator coil with the requisite refrigeration components including the refrigerant lines you mention.
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-

Dan LeBlanc

I thought of an electric compressor for the 1953, but, the main drawback is the huge power draw they require for very little BTU's they put out.  I'd just restore the system as others have said.
Dan LeBlanc
1977 Lincoln Continental Town Car

1969cadillac

hello ! thankyou for your comments .

Q how good was this dual system to start with ? When I bought the car , the front system had some gas left in it , but the rear system was clogged and has NOT worked for years....

Q I am upgrading to 134A gas ..... the orig GM compressor is old and not suited to the new gas . I have a Sanden SD7H15 heavy duty comp / 155cc - is this large enough for a dual system ??

thanks ,Murray Mules


"Cadillac Kid" Greg Surfas 15364

Murray
Unless someone has modified your car the refrigeration side of the AC is one system so if the front is holding gas so is the rear. You may have to do dome repairs and probably clean the evaporator coil. When new that system performed flawlessly but by switching to R 134a you should expect a substantial decrease in performance most noticable during low speed high temperature operation.  For capacity theA6 compressor still is the larger of the Sandens. If you want to go go to an electric compressor drive. System for the rear I would suggest that a capacity of 12000  BTUs is required and IF you can find one to operate on 12 volts you are going to need to do some serious electrical system mods.
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-

Scot Minesinger

I agree with the others restore the original and it should work fine.

However as Greg points out the r12 will be adequate capacity.  The 1970 and older Cadillacs converted to r134 just do not have enough capacity to meet hot day cooling requirements.  They take the sting out of a 90'F day and manage OK on an 80'F day.  The 1971 and newer seem to do much better with an r134 conversion, due to large condenser and higher airflow (I theorize).  I drove a 1975 r134 converted Cadillac on a 95'F day at 1pm and on low auto and it ran away with it.  This would not have happened on my 1970 Cadillac converted to r134.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

1969cadillac

Greg , thanks for your advice . - think I will still with standard !

The evap on the rear was blocked...

Do you think the sanden comp I have do the job..... or is borderline.....?? or should I just get a GM A6 and put it on ??

I have the same comp I my deville 69 .... but of course it is only a single system

your thoughts please

Murray Mules

"Cadillac Kid" Greg Surfas 15364

Murray
If this were mine I would use an A-6. If you have the original compressor be sure and re use your original clutch/pulley with a new bearing in the pulley.
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-

cadillacmike68

First the old gimormous A6 compressors are very durable.

Next, I must disagree on the bashing of R134a.

My 1968 cools as good as a new R12 system even here in Florida.

The key is having someone know what they are doing with the POA and receiver dryer. (both of which should be replaced in something as old as a 1969). Other than those two items the only other change needed are the r134a fittings. The compressor, condenser, evaporator, etc. can all remain.

The lines of course should be replaced, but the original ends can be re-used if you have a rubber and hose company nearby who can re-do them for you.
Regards,
"Cadillac" Mike

1969cadillac

THANKS MIKE!!

I think I will go with the A6 and hope it lasts

I am also going to use a POA uggrade kit on both ends...

I think I can get it to work

Murray Mules

cadillacmike68

You can't go wrong with a properly adjusted POA and R134a. The newer ones, yeah they are slightly different in appearance from the originals, can be adjusted for optimum efficiency, and the original condenser is so huge, that it will cool just as good as an original R12 system. I know because even today temps will hit 90+ on the asphalt and the car cools very nicely - when I use it - since most of the time the top is down.

It needs clean lines, a good flush, the proper oil and you should be fine.
Regards,
"Cadillac" Mike