I just got an 850, it had sat around without being started for over a year. I got it running recently, the ac doesn't work right. When I hooked up a pressure guage to the port, it barely moved. I put in about 1/3 can of 134a in and now the guage reads about 40 and the compressor will kick on and off. While the compressor is on the pressure will drop to about 20 and then back to 40 after it cuts off.

Any ideas?

 

The freon level is still to low.The compressor cycles when it is low on freon.

 

so should I keep filling it?
What PSI should I be shooting for on the port?

 

I think is is about 60 Psi.
IM not 100% sure the car holds a total of 1.63 Lbs total.

 

thanks, I will try adding some more.

 

Let me know how you make out.

 

I tried again to get it filled and still couldn't get the compressor to stay on.

Do you think something is clogged up?

 

The other thing to make sure of is that the cooling fan is coming on.If the fan doesn't come on the pressure gets to high and it shuts off.Unless you also have a leak and it is leaking out fast.

 

I thought about this some more.
I think there is a leak beyond the ac compressor.
If I fill it when the compressor is off, I can hold the pressure fine. Once the compressor turns on the 134a pressure drops and never comes back.

Is there a typical place on these cars that a leak will occour?

 

The easiest way to find it now is to add A/C dye and let it get a little low then check it with a black light.
Then you will know where the leak is.

 

Is that 60psi when the air is on or off?

 

That should be when it starts running.As it is on and the system gets colder the pressure will drop some due to temp.It will drop down to about 38 then kick the compressor off so the system doesn't freeze up.

 

This one is still bugging me, it doesn't seem like its leaking anywhere. The system had dye in it already I found out by letting some of the pressure out from the port. I couldn't see any traces of it around the compressor, dryer, hoses, or condensor. Can I bypass the low pressure switch to see what happens?

 

Yes you can bypass the low pressure switch.
Have you looked for dye under the car yet?

 

yup can't find dye although I found some antifreeze on the radiator and oil on the oil pan.

Is there a high pressure port where I can hook up my guage?

 

No high pressure ports on those cars.

Another place you can look for dye.
Remove the lower dash panel on the right side of the car.
Then remove the metal knee bolster.
Then remove the blower motor resister.
If you look in there to the left you can see the evaperator.
If you have a black light it will be easy to see dye if it is leaking.

You might also want to remove the glove box insert.

 

I couldn't find any leak on the evap by looking inside past the blower resistor.
I watched the guage while jumping the pressostat switch, it would go all the way down to 0 when the compressor was running.
I tried adding more 134, and put in all that I had and I was then able to get the guage to stay at 20 while the compressor was running.
I will buy another can tomorrow.

I noticed the evap was really dirty. This car didn't originally have a filter on it. I got one for it, but there wasn't a frame to hold it so I just laid it over the airway where it would go normally.
is there anyway to clean the evap without 20 hours of work getting it out?

 

Some places sell a foam that you spray into it and then run the A/C and it will clean it out some.

 

well, friday I put about an entire can in, I got the pressure to a steady 25psi while the compressor was running. So far so good it still works well.
I think I should add some more 134a.

 

Add a little more should be at about 40 psi.