Low pressure too low

[Frago]

Hi to all
I'm french and new on this forum.
I got a problem with my buick park avenue 91.
I changed my AC compressor by a new one. Flushed all the components, evaporator, condenser, hoses.I changed the bottle/dryer, the orifice tube and replaced it by an adjustable one from UAC. I vacuumed the system, and put two and half can of Duracool gas. Still the AC doesn't work. I forced the compressor clutch with jumper straight to the plug on the compressor. It makes cold but the low pressure goes close to zero!
I wonder if the new orifice with adjustable device is responsible of my problem, ref of this tube is UAC EX7000C and it should be ok for my car dixit Rockauto.
Any idea?
Thx for helping

[tbirdtbird]

Duracool is propane.
It requires substantially less fill than its R12 or R134 counterparts, per the website.
I am not able to comment on the OT.
Do not run the system until this is sorted.
Jumpering a compressor is not a good idea.
If you flushed the entire system then what did you do for oil?

This is a cobbled system and I am not able to comment further, this is above my pay grade, we will need to let the other experts chime in

[JohnHere]

Hi to all
I'm french and new on this forum.

Welcome.

I got a problem with my buick park avenue 91.
I changed my AC compressor by a new one. Flushed all the components, evaporator, condenser, hoses.I changed the bottle/dryer, the orifice tube and replaced it by an adjustable one from UAC.

Curious as to why you changed the compressor and installed an adjustable OT. Are you sure that you removed all traces of the flushing chemical out of the system? Did you use a good electrical vacuum pump to evacuate it, and for how long?

I vacuumed the system, and put two and half can of Duracool gas. Still the AC doesn't work. I forced the compressor clutch with jumper straight to the plug on the compressor. It makes cold but the low pressure goes close to zero!

Flammable hydrocarbon refrigerant alternatives like Duracool aren't EPA approved in the USA, so they aren't used here...at least not in motor vehicles. I believe they are allowed to be used in Europe, though, due to restrictions on the purchase and use of R-12 and R-134a by citizens.

Regardless, I can't say whether 2-1/2 cans of Duracool is the right amount for your system since we don't use it here. However, the original specs for your car (in the USA) call for 39 ounces of R-12 and 8 ounces of mineral oil.

Zero pressure on the low side is preventing the compressor clutch from engaging. As said previously, it's never a good idea to force the the system to run by jumping the clutch directly to power because of the risk of little or no oil circulation back to the compressor.

I wonder if the new orifice with adjustable device is responsible of my problem, ... .

It could very well be that the adjustable OT just won't work with Duracool. If you have a professional Mobile Vehicle A/C shop in your area, I suggest taking the car there. They will be able to properly convert your original R-12 system to R-134a, recharge it, and ensure that the system is working correctly before releasing the car back to you.

[bohica2xo]

First, stop with the jumper wires before you let the smoke out of an expensive and hard to replace electrical component.

1991-1994 Buick Park Avenue cars share an ATC panel with other GM Luxury cars of the same years. That panel gathers data from several sensors, one of which is a refrigerant pressure sensor. If the pressure is out of range, it will shut the system down to avoid compressor damage.

As I recall in general those ATC's would revert to "ECON" on the control head when they lock out the compressor. There we all sorts of issues when converting the Buick and Cadillac cars of that era to 134a, because they system pressures were different enough to produce trouble codes.

That system would not deal well with any sort of variable orifice tube. Replace the orifice with a stock part.

HC blends that mimic the P/T curve of R12 do work very well when used to fool the control system in to thinking it is still filled with R12.

There should be at least one, and possible two switches mounted in the compressor, as well as a switch mounted in the high side line. There is a lot of electrical to troubleshoot in that system.

It has been a long time since I saw one of those in person. Another poster here (GM Tech) has a lot of experience and may remember how to access the trouble codes in the HVAC control head.

.