When I see a POA system with 29psi low & 155 psi high, all I see is an evaporator with no airflow. Is the suction side cold? Do you have a low side port on the compressor side of the POA? Not all systems have this, but some do. If you raise the engine RPM to 1500+ does the evaporator stay at 29p...

Pushers are always a handful with A/C. Is this the dash A/C you are working on? The long lines & odd configurations that are manufacturer specific can lead to some odd pressure readings. Are the service ports both back at the compressor? Sometimes you will find a low side port near the evaporato...

Because a diode tested by itself will give a resistance higher than the coil in either direction on your DMM, you need to apply a small load to cause current to flow through the diode. The resistor is used to build a voltage divider. With the coil & diode assembly connected as one of the two res...

The 1999 Safari is built on the GM P32 or Workhorse chassis. HT6 compressor.

Coach builders did all sorts of things with the dash A/C If they used mostly the GM P series parts it has an orifice tube.

Which engine is in this unit?

You say it works "All Day" Does this mean that when you drive it for several short trips in the daytime it always cools? Or is this car used like a delivery vehicle running almost constantly? When it stops working at night, does this coincide with an action like using the headlights? What ...

Always a tricky test. Because the coil & diode are in parallel, the resistance through the coil is the same both directions. But the diode has a 0.5v drop one direction, and is effectively an open circuit the other direction. A DMM will not display the very small change when switching polarity. ...

Oh, it definitely has broken valves with a full charge and no differential. There is crap in the system. Several broken reed valves went someplace. Pull the discharge line out of the vehicle. Put one end of it in a clean container & flush it out with a spray can of brake cleaner. See what you ge...

How much refrigerant is in the system?

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That is the half Ford half Volvo with the DKS15 compressor with two serpentine belts on the clutch.

Are you sure it is turning?

Sounds like you have several issues. 1) Clutch gap. Obviously the compressor was NOT turning the first time you tested. With 100k on the clock an excessive clutch gap is a given. Adjust the gap. 2)Possible Blend door issues. With a cold & sweating line in to the evaporator something is getting c...