[DeTomaso] A/C test results

[Tom Shinrock]

 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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