AC Low Pressure Service Port 2001 Bonneville
 

With all the hot weather we've been having lately, I'm thinking my AC isn't working as well as it used to. Being a 2001 with over 200k, I can imaging that the R134a is lower than what it was from the factory. So I'd like to check the R134a pressures to see if it is low or if it is old-timers kicking in.

I was able to get a set of gauges and have located the high pressure service port on the right front corner. However, where is the low pressure port? I've traced both hoses from the compressor all the way to the firewall and I only see 2 ports, both on the same hose (see attached). One has interior threads and is on the expected high pressure fitting.

I also have been reading in another thread that the Bonne's have a higher pressure than some of its counterparts. Does anyone have the temperature/pressure chart that covers the 2001?

Thanks for setting me straight.

Pretty sure you have it right there. The high side is the larger valve, the low side is the smaller valve, and the expansion valve is right in the center.

BTW, looks like high is on the left, low is on the right.

temp/press chart for 134 is going to be the same for all. but you cant take the numbers as gospel there are many factors that change like obstructions or dirt in the coils etc... most gauges have temp readings on them and you should see roughly 30deg reduction from ambient if you have all the windows open and on recirc. max fan speed. high side press for 134 is generally twice the low side

The ports you need are both there. The orfice tube is located in the line between the 2 ports. Low side pressure should be between 30 to 40 lbs with A/C turned on. Do not overcharge as 134A will not be as cold when overcharged where as R12 will get colder the more you ad. Your inside vent temp when A/C on with fan on low should be about 34*.
Hope this helps.

I hope to not highjack this thread but noticed you mentioned a vent temp of 34*.
I am having issues with my vent temps not getting low enough.
I have had the system gone through and the correct 2.2 lbs. of gas is present.
But vent temps remain around 60* at idle (granted it has been blistering hot here in the midwest lately).
Going down the highway for 10 minutes or so temps slowly drop to close to 50* through
the top vents.
If I choose to recirculate the air it will drop to 44* or so. And lastly when the above is
done and I switch to a combo top vent and feet it further drops to closer to 40*

Any slowing down or stop and go driving and vent temps start raising quickly.

Any ideas about what is going on? My local guy suggested the compressor may be on
its way out and wasn't to sure about that it seemed to me.

So I continue to drive it (02 Bonneville SE 78K miles) and wish for those above stated 34* temps
and wish I didn't have to drive 15 minutes to finally get some half way cool air blowing.

Thanks for your replies...
Jeff D.
St. Louis area

Sounds like you may need to do a EVAP clean. Take a look at this writeup, should be close enough to get it done. https://www.gmforum.com/normal-maintainence-138/evap-clean-278997/

I will take a look as soon as the temps aren't 100* out.
Hope that is it, or at least improves the situation.

Thanks
Jeff D.

sound more to me like your condenser has some crap in it

Why is that?

Jeff

Thanks for the help. I'll probably check it out next weekend.