A/c system full of 134 but has a mind of its own...ideas?

[TooManyAudis at aol.com]

From: "Obin Olson" <oolsen1 at ec.rr.com>
Subject: A/c system full of 134 but has a mind of its own...ideas?

hello all, I took my a/c system apart last year put in new seals new dryer 
new orface thingy and filled it up with 134 and new oil..worked great last year 
NO problems at all..now this year it works great WHEN it comes on...seems like 
the pattern is when it's cold in the morning and I first start it MAY come on 
and cool if it does it will stay cooling for say maybe 10-20min of driving 
then it will stop compression and NEVER come on again that day..next morning it 
may or may not come on but it never comes on in the same day after it shuts 
down....what in the world could this be? the A/C relay IS clicking when you push 
the A/C button ON inside but the compressor is NOT getting 12v..if I jump the 
compressor it will work and cool...what could cause the thing to shut down 
after a while and not start again till the next day??

thanks for any help on this weird issue

could it be a bad water temp sender in the engine? if so what one? 

___________________________________________

A few of things to consider when working on A/C:

1.  134-A will almost always leak out to some degree on a conversion.  This 
will probably happen even if you replace all the seals in the system.  134-A 
will leak through R-12 hoses.  So, I plan on charging up my system every spring. 
 1 Can almost always does it, although a few ounces may be needed in late 
august.

2.  Your main safety cutoffs are due to low-pressure and high pressure.  
Usually the low pressure is due to leakage and can be addressed with a re-charge.  
High pressure is usually due to some sort of blockage in the system.  On my 
200q 20V, this was due to my expansion valve / orifice tube being full of crud. 
 This valve also acts as a filter, so it is a regular replacement item.

3.  Temperature affects pressure within the system.  Your system may be 
slightly blocked and yet still work at lower morning temps, but after a few minutes 
of operation, the system has pressure high enough to trip the high pressure 
switch.  This is usually an intermittent thing, i.e., cuts out in stop and go 
traffic, but ok with sufficient air flow over condensor on the highway.

4.  Your guages are usually the best indication of what is happening 
internally in the A/C system.  If you don't have a set of A/C guages, stop by a pawn 
shop or buy a set on E-Bay.  Any conditions of low or high pressure will be 
evident at this point.  You can also see the pressures adjust as the system kicks 
in or cycles.

5.  The Bentley is a great source for troubleshooting A/C problems.  On my 
200q, I followed the symptons via a flowchart and came to the correct diagnosis 
within a few minutes.

6.  Good luck, even with all the proper equipment and diagnostic tools, A/C 
repairs can be preplexing and frustrating.

-- Tom  

91 200q 20v