1987 Buick Grand National R12 charge

[Ajrothm]

Engine speed revved to 1500-1800 rpms,
All other settings are the same.

[Ajrothm]

Engine revved to about 2000+ rpms.

[Ajrothm]

That is the picture with 111* on the thermometer. Pic 2 on this page.

[tbirdtbird]

Sry did not see that thread had gone to pg 5

[Ajrothm]

So today while driving, it took about 10 mins to get into the low 50s vent temps. At idle I’d see 49-51* and the compressor stayed on pretty steady. When driving the temps seemed to increase to about 53-57* at 50-60 mph (2000-2200 rpms) and the compressor seemed to cycle on and off a lot. I can see on my laptop when it cycles and it was cycling about every 20-30 seconds when driving at speed. That seemed really excessive to me.

[Ajrothm]

This is how I can tell the compressor is on/off. The laptop shows “AC ON” which means the compressor is on. And it cycles a lot when driving...but at idle it’s pretty steadily staying on.

[Ajrothm]

At first I thought the charge may be a little low but, after checking pressures in these higher ambient temps, the pressures seem more in line. So I didn’t add any Freon. I was worried the high side pressure would go to high.

So I’m not sure what to do now.

I know it’s something with the AC system and not heater valve/blend door etc etc. just not sure what to try.

[tbirdtbird]

OK, glad you were able to get us some pix.
The problem is NOT with your AC system. Except that the condenser is unable to do its job. Wait there is more....
My nephew is a racer and I shared the pic with him that shows the turbo. And he said...
"You have mega heat soak problems going on under that hood, mega."

1) The turbo and the down pipe are sitting right below the accumulator, thus you are asking the system to remove not only the heat from the cabin, and the heat generated by the comp itself, but the also heat soak from the turbo and the down pipe. Which by itself is way more than the other 2 sources of heat the system is removing. You are lucky you are getting any cool air out your vents.
They make a turbo blanket, and there is one out there at Summit with your name on it. Do it. Also, you need exhaust wrap on the down pipe, and it would also help to use exhaust wrap on the accumulator, which is a large aluminum heat sink! You can use hose clamps to keep the wrap on.

2) He said that the factory setup for that turbo is to have the intercooler on the INSIDE of the radiator, thus not blocking airflow for the condenser, there is a boatload of space there. Due to the presence of the alcohol injector, and location of the intercooler, he feels you have modified the system from factory.

3) It has not been mentioned but you most likely have an R4 on there and he would remove it asap, toss it in the junk, and replace with a Sanden. Heat-wise, the R4 is doing you no favors.

With all that underhood heat, I would be shocked if you were getting a solid column of refrigerant into the evap.

And by the way, Miles (nephew) knew that was a Grand National from that one pic, and he suspected it was an '87. He is a racer, mechanic, and a restorer, and has worked on literally thousands of cars of all types over the years

Brad (Bohica) has always said there is always a back story......

[Ajrothm]

You and he are correct... there is a lot of heat load under the hood.... but it’s the same heat load I had when it used to blow 38* less then 2 years ago...

Here was all of my numbers from 2 years ago when I first charged it.

[tbirdtbird]

Not sure how we are able to act on anything other than what we are given today. Something is obviously different. And the cycling at speed may be the HPCO.

If you choose not to address the heat load issues, that is up to you. The laws of physics will not be denied.

Lots of people come here and choose not to follow the suggestions given

I'm off to the next thread