[DeTomaso] FW: A/C test results

Thu May 16 17:13:45 EDT 2013

Tom,

Thanks again for the link to the AC performance test process video. It is
really great to have some benchmark numbers for comparison.   I spent some
time creating a check list from the video and took temp readings today.
The ambient temp at the time of the test was 83, sunny and humidity of about
42 percent.   

I first started to do the test in the driveway with the windows down and on
a cold startup and warm up like in the video.  I was getting a 55 degree
delta between the condenser air inlet of 87 and the evaporator air outlet of
32, but for some odd reason the temp drop across the condenser was pretty
low.    

I decided to take the car for a short drive and then came back and parked in
the garage out of the sun.   At that point I had a 54 degree delta between
the condenser air inlet of 84 and the evaporator air outlet of 30.
Recommended: a minimum of 30 but 40 would be great.  The windows being
closed did not make much difference on the evaporator temp.  The condenser
inlet temp was 143 with an exit of 100 for a 43 delta.  Recommended: a
minimum of 20 to max of 50. 

I was not able to measure the evaporator efficiency because all of the metal
parts of my suction line the evaporator are wrapped with the black AC
insulation tape.  But, I could feel that the insulation and rubber hose was
pretty cold meaning that the system is charged well and the expansion valve
is doing its job.  

In the video they say a 2 degree delta between the condenser to evaporator
temp compared to the condenser temp drop is good efficacy, but as you can
see I'm way over that number with 12.  

I'll do some more testing later in the summer when it gets hotter, but from
their numbers, I've apparently achieved Pantera AC nirvana.  After all these
years of wrenching on the AC system and the never ending cost, the high
density condenser seems to be the key to it all.   

For those of you that are thinking about a new condenser I found out that
even though the parts book shows only one part number there are two
different sizes.  The 71 cars with the large plastic shroud uses smaller
size than the later cars with the flatter metal shroud.      

Mike         

From: Mike Dailey 
Sent: Wednesday, May 15, 2013 9:39 PM
To: 'Tom Shinrock'; 'detomaso at poca.com'
Subject: RE: [DeTomaso] A/C test results

Tom,

That is a great video.  I need to go through it and document the recommended
temps and then check them with my IR temp reader.  My condenser air inlet
temp ratio to evaporator air outlet was 55 degrees or better today and in
the video they are saying 40 is great.  My doors and windows were closed
though.  At 82 degrees today I had plenty of cooling that doesn't seem to
change at highway speed, but I don't have any highways close by where I can
drive over 70 for a prolonged time.  So far it looks like my new high
density condenser is removing a lot of heat.  The big question will be what
happens with our Atlanta high humidity 95 degree weather this summer.
Great info and it is a treasure hunt for sure!

Thanks,

Mike   

From: Tom Shinrock 
Sent: Wednesday, May 15, 2013 8:52 PM
To: 
Subject: Re: [DeTomaso] A/C test results

Mike,

Welcome to the A/C treasure hunt.   Sounds like we have similar experiences
in that vent air is not very cold at high way speeds and too cold at low
speeds.   I was googling on ideal A/C temps and found a youtube video that
explained how various parts of the system can be measured to verify
operating efficiency ( http://www.youtube.com/watch?v=uRbWx23Tgsw ).   I
don't have the fancy measuring equipment but I used my temperature probe to
measure the air temp entering the condenser (80 deg) and the air temp
exiting the vent (36 deg) at idle.   The difference of 47 deg exceeds their
stated minimum of 30 deg, but I still thinking it's too cold at idle making
me wonder if I have too much R-12 in the system.  I going to talk to some
A/C shops and see what they have to say.

Good luck in your quest.

Tom
#5186

-----Original Message-----
From: Mike Dailey <panteraplace at hotmail.com>
To: detomaso <detomaso at poca.com>
Sent: Wed, May 15, 2013 3:32 pm
Subject: [DeTomaso] A/C test results

Those of you that have been following my A/C blog on Pantera Place
http://www.panteraplace.com/page123.htm know that I've been working on my
A/C system for a few years now.  It always seems like I'm just another $300
away from total success and A/C nirvana.  This may be the most expensive
Pantera A/C system in history.  

In November of last year I thought I'd finally found a combination of stuff
that really worked.  But, I've been hesitant to publish anything on it until
I could test it in the Atlanta heat and humidity.  The problem I've had with
the testing, is the weather has been really mild here so far and when it has
been warmer the humidity has been fairly low.   

Today it was 82 with a low humidity of 37 percent and sunny.  I made a test
run of a combination of stop and go traffic and about five minutes on the
freeway at 65 to 70 MPH.  The evaporator exit air temp stayed pretty much
the same between the 65 -70 and the traffic, in fact a bit too cold, between
25 and 30 degrees before my deicing switch dropped out the compressor.  I'm
getting some frost on the evaporator coils.  The inside of the car was 65
when I took it out of the garage and even with the high solar heating the
A/C lowered that temp slightly throughout the drive of 20 min. 

I think the deicing switch would work a lot better if the temp sensing probe
on the Pantera was located further toward the exits in the evaporator box.
On my 71 it enters the box where the evaporator return line exits the box
and I think that is too close to the fan inlet/return air.  Or I may need to
add a new switch to my list of stuff!   

I'm running a new high density condenser with smaller aluminum tubes that
has 30 percent more of them compared to the original old bass tube unit.  My
old condenser was original with decades of exhaust fumes corroding it and
most likely built up cooked A/C oil inside the coils.  I'm still using
Freeze 12 with A/C mineral oil. 

The new condenser seems to make a huge difference even though it is in the
stock position with a stock fan.  Before I changed the condenser I tried new
1200 - 1450 CFM fan but oddly the stock fan seemed to work better.  I
removed the fan feedback diode to pick up an extra .6 volt of power.   This
is all tentative until we get some hot weather, so don't rush out and buy a
new condenser.

I'm not sure why I keep spending money on this dang system other than it
bugs me when something does not work correctly on my car.    

More later when we finally get some of our lovely Atlanta heat. 

Mike            

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