[DeTomaso] Pantera AC upgrade

[boyd casey]

After doing some research and asking for the help and opinions of our
brother hood I have found devised an updated AC system that does not require
moving the condenser to the the front of the car  and promises to improve to
some extent  the cooling capacity of the pantera with R134 and the common
conversion from the york compressor to the Sanden 508.
 My preliminary research into the problems with the accepted upgrade of the
York compressor to the Sanden 508 revealed several problems and faults with
both the original system and the upgraded system.
*1*.. Neither the York nor the Sandeen  came with a high / low pressure cut
off switch. This issue was further exasberated when the upgrade / conversion
included the switch from R12 to R 134. The R 134 operates at a much higher
pressure and and when  over pressure  situation occurs  ( which is
apparently not uncommon while using R 134) it causes the AC hoses to be
blown off at their weakest points which can necessitate the replacement of
the AC hoses running from the compressor to the heater core under the dash
board which on early cars (1972 and before) run through the rocker boxes and
are a major PIA to replace. The stock dryer does not have a port to install
the High / low cut off switch. You can purchase a dryer with a port that
allows the installation of the high /low pressure cutoff switch for $14.99
(or $40.00 if you want the bling of chrome plating) The switch is the wired
in series with the rotary switch on the dash board and will shut down the AC
compressor if either an over pressure or low pressure condition exist. The
Hi/ low switch is available for $9.99 and $5.99 for the plug and pigtail.
*2.* The next change to the normal upgrade process is the replacement of the
stock condenser fan with a high powered sucker fan. Procomp makes a variety
of fans that combine  high CFM with a low amp draw which when combined
increase the cooling capacity of the condenser. I found a 10" Pro comp fan
that is rated at 1000 CFM and is Chrome Plated ( is you are looking to dress
up your engine compartment  for only $29.99 plus $8.00 shipping.) I also
found one in black for $17.00 and $10.00 shipping. These are supposed be
made to fit with out to much difficulty.
*3.* If you really want to improve  the cooling capacity and overcome some
of the difficulties faced by operating the condenser at the back of the car
the best solution (without moving the condensor to the front of the car is
to go with a parallel flow condenser. They are available in a variety of
different sizes and configurations and prices. The one I found and have
decided to go with is available from Nostalgic Air. It is a unit that
combines a parallel flow condenser two 12" fans and a polished aluminum
shroud all for only $239.99 the two fans move 1900 CFM  (950 cfm each fan)
and the draw 8 amps per fan (16Amps total)
The basic info is as follows :

Condenser core size: 14" x 25"
Overall condenser size: 14-1/2" tall x 27" wide
Overall thickness: 3-1/8"
Fan CFM (per fan): 950 CFM
Total CFM: 1900 CFM (both fans mounted on condenser w/ shroud)
Amps: (per fan) 8.0 amp draw
Total amps: (16.0 amp draw (both fans mounted on condenser w/ shroud)

Condenser with shroud and dual fans
$239.99<http://condenser%20with%20shroud%20and%20dual%20fans%20$239.99/>

After considering the costs of condensers ,fans  , and the fact that  a self
fabricated set up would not include a shroud for $239.99 I felt this was the
way to go.

*4.* The single most important and expensive item is the condenser. After
researching the sanden web sight I wondered why no one had ever used a
compressor besides the  Sanden 508. I had written a post a few days ago
asking if anyone knew why the Sanden was referred to as a "Rotary"
compressor since it is piston operated and not rotary. No one supplied an
answer. After speaking to some air conditioning people I decided to go with
a sanden 709 instead of the 508.

The 508 has 5 pistons and 138cc ,8.39 C.I.D.  displacement ,the 709 has 7
pistons and 154cc ,9.36 C.I.D. t They both have the same external dimensions
and mounting dimensions.

The 508 has a max operating rpm of 5K and the 709 has a max rpm of 6K.

Having a compressor with a higher displacement,and or operating speed is not
in it's self enough to necessarily increase the cooling capacity. Since I am
also going with a more efficient as well as larger condenser that is also
incorporating two fans  these factors combined with the higher capacity
compressor should work together  to help over come the less efficient
cooling capacity of R134 and the handicap of a rear mounted condenser.



The condenser, dryer and compressor can all be used with R12 or R 134. I
have some R12 left. I have not decided whether to go with R12 or switch over
to R 134 If I charge the system with R12 and then decide to switch to R 134
I will have to completely flush and clean the system as well as change the
Dryer again.

I don't know if I am going to have to replace the expansion valve. I have
read that it is a good idea to replace it when you have the system
evacuated.

This is my plan for upgrading my ac system. If anyone notices an obvious
error or something I may have overlooked please let me know what it is. I am
no AC expert and this is my own plan for upgrading my AC system. If it works
well I will share the results with the list. If it doesn't I will chalk up
another one to learning the hard way.

Boyd