Should I try control valve or just replace compressor

[northbay]

Hello,
On a 2005 LeSabre it has poor cooling performance. At 80deg ambient, vent temp at 72deg. Low side is 55-60, high side 170. Thought maybe a bit low, put about 10 oz in, low stayed same, high came up to 200, but no better cooling. I'm considering trying just the mechanical control valve & orifice (cheap & easy to try). But would more experienced troubleshooters suggest replacing the compressor & not messing around? Appreciate any advice or help.

Thanks,
Ray

[Tim]

Reclaim the refrigerant, vacuum it down, and charge it to spec before doing anything.

[JohnHere]

I agree with Tim.

Although the compressor might be "tired," pressures can often throw you off with a variable-displacement compressor. Best to weigh-in the OEM-specs charge first, then see how it performs.

How many miles on this car?

[northbay]

it has 90K

[JohnHere]

it has 90K

With 90,000 miles on the clock, the A/C system probably would benefit from a new compressor, along with a new OT and accumulator, which contains a desiccant.

On a 2005 LeSabre it has poor cooling performance. At 80deg ambient, vent temp at 72deg. Low side is 55-60, high side 170. Thought maybe a bit low, put about 10 oz in, low stayed same, high came up to 200, but no better cooling. I'm considering trying just the mechanical control valve & orifice (cheap & easy to try). But would more experienced troubleshooters suggest replacing the compressor & not messing around? Appreciate any advice or help.

A low side of 55-60 PSI translates to an evaporator temperature of about 62°F, so I'm not surprised by the poor cooling performance.

Let's do it this way: Recover the system (or have it done) and have on hand a replacement OT while the system is empty of refrigerant. Inspect the original OT when you remove it. If the screen is loaded with black gunk and metallic/plastic debris, then the compressor is probably shot. On replacing the compressor, the condenser would also have to be replaced to maintain the compressor manufacturer's warranty. Flushing whatever remaining original components that can be flushed—like the evaporator and lines without mufflers—would also be a good idea and possibly even required by the compressor manufacturer for the reason mentioned above.

After you reassemble the system, uncapping and installing the accumulator last, evacuate and re-charge it to OEM specs or to the specs appearing on the under-hood decal, which takes precedence. Don't forget to put into the new compressor the correct amount of oil before you install it.

[northbay]

ot.png (155.64 KiB) Viewed 2655 times

Finally got back to this car. Recovered and recharged to oem level. No help, still poor cooling. Pulled orifice and it looks like this. Not a good sign, this is going to be entire system as John described?

[tbirdtbird]

Yes, unfortunately. The comp grenaded and took out everything downstream as he described. Please remember that a condenser cannot be flushed

[JohnHere]

Finally got back to this car. Recovered and recharged to oem level. No help, still poor cooling. Pulled orifice and it looks like this. Not a good sign, this is going to be entire system as John described?

Based on the look of the OT, I'm not surprised that the cooling performance is poor. Little to no refrigerant is making it through to the evaporator.

If you'd like cool A/C in this car, you'll definitely need to do an overhaul, as tbirdtbird said. Service it properly, and it will cool properly. Might as well tackle it now before the heat of Summer arrives.

As for the components you'll need to replace, figure on a new (not rebuilt) compressor, new condenser, new accumulator, and a new orifice tube (yellow/white [.062" orifice] is the correct part).

IIRC, the 2005 Buick LeSabre didn't have mufflers or "cans" on any of the lines, so you should be able to flush the lines if they're otherwise in good condition. The evaporator can be flushed without removing it by attaching some clear plastic tubing to the inlet and outlet fitting at the firewall to inject the solvent and catch/inspect it as it comes out. Make sure that you thoroughly dry-out the components you've flushed by blowing through them with nitrogen (preferred) or clean, dry shop air. Of course, you'll need to put back in the entire amount of oil called for by the manufacturer's specifications, as well as the exact amount of refrigerant by weight.

The specifications that I have for your car (all engines) call for 38 ounces net weight of R-134a, and 9.0 fluid ounces of PAG-150. If you have an under-hood decal that differs, the decal takes precedence.

[northbay]

ok, I'll replace all of those parts and the suction/discharge line as it does have mufflers. I'll flush the evaporator and its lines. I definitely want to do it right and not have to go back into it later so I don't mind spending a little more for a better chance at success.

On the oil, I understand the idea of draining the old compressor and accumulator and putting back in the same amount on new parts. But what about the condenser, it should also have some oil in it & I can't drain that to see how much? What about the evap? Once I flush that, no way to know.

I appreciate everyone's advice & suggestions. I'll let you know how it turns out.

Ray

[Tim]

If you are in the US compare our price to what you might find online. We do nto have the discharge line. Find a better price item to item. Let me know and I'll see what can be done.

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