[DML] A/C troubles

["Warren Wallingford" <warren@xxxxxxxxxx>]

The question about the orfice tube reminded me that air conditioning season has come to South Texas this year and will spread to the hibernating North soon.  The A/C problem we hear most about is that the refrigerant has leaked out.  The complaint takes the form of "it's not blowing cold" or "the compressor goes off and on" or "the compressor won't engage".  Without going into a detailed description of the low-side cylcling used to regulate the system, it will suffice to say that all of these symtoms are usually caused by a low refrigerant level.  In the happy days before global warming, we just pumped in another can of Freon, available everywhere for a dollar a pound.  Now R12 costs $50 or more per 12 oz. can and you need a degree and a federal certification to buy it.  Worse, it will run right out the leak we can no longer afford to ignore.  

Many A/C shops pressure owners to retrofit to R-134, the refrigerant that modern cars use.  This holds the promise of cheaper refills but often sidesteps the problem of the leak(s).  No matter which refrigerant is used, if the intake pressure is too low, the compressor will cycle or stay disingaged and the system won't cool.  At DMCH, we do not do the R-134 conversions and we encourage owners who call to stay with R12, despite the cost.  Freon is available and it works better than R-134 in the Delorean.  We emphasize closing the holes and maintaining the components of the system rather than pasting over the problem with constant recharging.

The most common places for the Delorean A/C to leak refrigerant is from the high side hose where it can come into contact with other parts of the car.  The top banjo bolt of the fuel filter has rubbed many a hole in hoses that rest on it unsecured.  Also, the cinch nut on the lower steering u-joint will quickly tear a hole in a hose that's not tied out of the way.  The lesson here is to tie the hose away from objects on the car that may dig or abrade it.  I have seen high side hoses develop pinhole leaks.  The clue was a light film of oil on the hose most of the length of the car.  There are plenty more places for leaks. A sneaky place is the Schraeder valves on the compressor.  The little o-ring that seals the valve will wear out and let the refrigerant out.  When the valves are capped by gauges, the detector won't sound the alarm, but the new charge will leak out when the gauges are removed   A good investment for a dedicated DIYer is an A/C sniffer.  It beeps along until it "smells" refrigerant, then the beep accelerates and raises in pitch.  Very handy. 

Here's a picture of that high side hose.  Part number 100748, $129.89.  http://www.usadmc.com/dmcstore/ViewPart.asp?PID=242&Qty=1&ShowCart=true
We have the Schraeder valve cores, too. 

Warren Wallingford
DeLorean Motor Company (Texas)
15023 Eddie Drive
Humble, Texas 77396 USA

http://www.delorean.com
800/USA-DMC1
281/441-2537
281/441-2813 Fax

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