2003 park avenue, 130K. AC system goes out. When I start it, there may be no fan, no AC, nothing. The lights on the buttons work. Then, suddenly, the who system may come on and work fine.

SOURCE: 1992 buick park avenue want

I went through the same senerio with my 92. finally after replacing all of the listed components the last in line was the crank sensor, it sits behind the crank pully and alignment is critical not much room for error. ithink the sensor set me back 30 bucks witsh i would have known before investing in the rest of the ignition system! good luck. KC

SOURCE: 95 buick park avenue ignition problem

What is the fuel pressure it has to be at least

1. Ignition "OFF" for 10 Seconds.
2. With ignition "ON," engine "OFF" and fuel pump running, pressure should be 333-376 kPa (48-55 psi). For additional fuel pressure testing, See: Computers and Control Systems\Testing and Inspection\Symptom Related Diagnostic Procedures\A - E Charts & Related Test Procedures\A Charts\Chart A-7 Fuel System Diagnosis
3. Have you tested the compression?
4. A totally plugged cataltic converter can cause tis too because the engine cannot breathe
5. to verify a plugged cat connect a vacuum guage to manifold vacuum and ccrank the engine you should get at least 2-4" of cranking vacuum providing the timing chain has not jumped and the cat is not plugged

SOURCE: Engine shakes when accelerates, lost power, Buick Park Avenue

Look for a bad coil pack. If you have the bank of three coils on the front passenger side of the motor, it is possible that one of them is going bad. This can be an intermittent problem since it failure is frequently heat related, and may not show up until the car is all heated up. It is simple enough to change one of these if you can figure out which one it is. There is a little device ( Spark detector) that can sense the sparks inside the wires. Get one and hold it close to each wire... away from the coils. The wire, that does not make the spark detector light up...is coming from the bad coil. (It is also possible that a spark plug wire is bad instead.) Good luck. Chip

SOURCE: Replace Thermostat in 1998 Buick Park Avenue

if you follow the top radiator hose to the engine you will see where it connects to the engine...you will want to drain some of the coolant from the radiattor but once you loosen the clamp holding the hose on you will need to pull the hose off and push it to the side out of the way. there are two bolts that hold the housing on that you need to remove where the hose was hooked up. once you take those bolts out you should be able to pull the housing out and the thermostat is right there.
i do wish to offer you an opinion on the thermostat i dont think its the problem..i think maybe your heater core is partially clogged and not letting the coolant get into the interior of the car as you are driving.if its blowing warm when you start it up and let it run and it gets warm and then get cooler as you drive thats going to be in the heater core since the thermostat is opening to let the heat in when you first start the car up to warm it up.

SOURCE: 95 buick park avenue wont start

Mine had the same problems and my buddy replaced my vacuum lines and my battery and seems to be OK. Now, though, if I turn it off for just a few minutes on a hot day, it won't start.