97 850 GLT A/C Doesn't Work - where to start

[tzanis]

Hello there,

I have exactly the same car and problem. I bought 2 cans of 134a coming with charging tool and pressure meter for 43 canadian$ with tax. Can you please write up what exactly did you do? I think my pressure with the engine off, is about 25psi. not sure if the evaporator leaks, even if it does, im gonna be using it only for the summer, so it would be fine to just recharge for now, to have it work and then do the dash job out. mine doesnt engage either. Any answer is highly appreciated.

p.s.(basically my question is about the low pressure switch you re telling about, where is it located and such, thanks)

[Ozark Lee]

The low pressure switch is on the larger A/C line that comes out of the firewall on the left side of the car. If you have 25 PSI static pressure the system is way low so you really don't need to jumper the switch as a diagnostic tool.

Once you hook up the R-134A the system pressure will start to climb and the compressor will kick in. It won't kick on instantly but give it a minute or so. Once the compressor starts to cycle the system will take refrigerant faster and charge quicker.

...Lee

[tzanis]

Thank you for the quick answer Lee. I will be trying it tomorrow morning.
Im sorry, but I have another newbie question, cause I dont really understand it. When I have the ac switch on the dash to off, the red light next to it is on. when i turn it to auto, light goes off. I tried it both ways to see what it blows, but of course like you said it probably is pretty low.

[tzanis]

I followed exactly the details, added more of the r134a, my ac engaged, and started blowing cold. Thanks very much Lee!, and everyone else that has posted info on that. I dont know if I need to add more, but my a/c is engaging and disengaging all the time though. Something like on and off all the time. I dont know if this is how it works, but what can I do for that? I ll continue to be lookin about that, cause I think i overread it in here somewhere, but did anybody else had the same effect?

[Ozark Lee]

If the system is cycling on and off then it usually means it needs more refrigerant. If you have the gauge then you should be reading - give or take and it is dependent on ambient temperature - upper 30s to lower 40s PSI with the engine revved up a bit. The clutch shouldn't cycle at short intervals.

A static pressure (compressor off) in the low 100 PSI range is typical but again it is all temperature dependent so don't panic if the gauge reads that high with the compressor off.

...Lee

[tzanis]

Thanks again for your answer Lee!!
I ll go charge it to 90-100psi with the compressor off!

I really appreciate your help!

[Ozark Lee]

You need to have the compressor on to get the refrigerant to flow into the system. I just gave you the static pressure so that you wouldn't get concerned when the pressure is real high without the compressor running. On a hot day even 140 to 150 PSI isn't out of reason but the static pressure by itself is pretty meaningless. If you get it to the 40ish PSI level with the compressor running then you are at least close if the temperature is in the mid 80s (F).

The real way to do this is to do it by volume or by weight but both are expressed in ounces and the specification can be confusing if it isn't expressly designated. The equipment needed to precisely charge the system is also very expensive. Since you likely have a leak somewhere "close" is good enough and you can see how long it lasts and make your permanent repair decisions accordingly.

...Lee

[tzanis]

Yes, I always do it with the a/c on, recycle on, and fan at full when I am recharging. I managed to get to about 35psi while running, and 90s when turned off. The compressor now doesnt go on and off like before. I used one full can 16oz, and I opened the second, and used a bit from the 2nd too. Now a/c is blowing cold. Thanks lee!

p.s. Like you said from now on, I ll just wait to see how long it goes, how much pressure I lost etc.. Good luck to other people that likely come accross the same problem.