1995 Buick Lesabre

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Mark86
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Re: 1995 Buick Lesabre

Post by Mark86 »

I’ll toss the gauges back on and do a test at 1800 RPM. I was comfortable, but the car was not heat soaked, it was in the garage. I think it could be better, but it is a 27 yr old car and I have no idea how good the AC system was from the factory. Compared to todays cars, the blower fan moves much less air (blower fan is new and working).
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JohnHere
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Re: 1995 Buick Lesabre

Post by JohnHere »

I recorded the nice, cool temperature in the photo (right-center vent) the other day after driving around on local roads for about 15 minutes in my 1994 Toyota Camry Wagon on a 99-degree day here in humid South Carolina.

This car has a TXV system as opposed to your CCOT set-up and also has a new evaporator.

In addition, I installed a new condenser, OEM TXV, R/D, and OEM Denso compressor. I flushed all the lines and hoses. Evacuated overnight, about 8 hours, and charged it with 30 ounces of R-134a. This system also contains 8 ounces of PAG-46.

It can be done. :D
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tbirdtbird
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Re: 1995 Buick Lesabre

Post by tbirdtbird »

Nice going John, you da man!! Great temp after a total rebuild!
What was your micron reading after that pulldown? Gonna guess less than 200

I can get that on my '59 Caddy I installed a VA system into, but reworked it considerably since I had no use for the stumble bum way they did things. You can tell Ice is no longer there.
My remaining beef is that the frost switch they supplied has a 20° differential. Someday I'll chase down a better one

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JohnHere
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Re: 1995 Buick Lesabre

Post by JohnHere »

tbirdtbird wrote: Fri Jul 22, 2022 12:38 pm What was your micron reading after that pulldown? Gonna guess less than 200
I don't recall the exact reading, but I do remember it being nice and low. Around 200 microns is definitely in the ballpark. Since it is my own car, I had the time, so I evacuated overnight. I'm glad I did.

Sorry to learn about Ice leaving there. Do you know where he is now?

My car has a thermistor on the evaporator. It tested good, so i didn't replace it. Fortunately, I have had no problems with the evap icing up, and the compressor seems to cycle nicely, just as it should.
Mark86
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Re: 1995 Buick Lesabre

Post by Mark86 »

OK, just ran some tests. To recap, new condenser (seals added), fans working, new Denso compressor, new accumulator, flushed lines and evaporator. Insulated lines to from evaporator. Temp gun is a RayTek Raynger, calibrated.

Tested in my garage, I use the OAT gauge in the car as reference, as it’s sensor is in the air intake filter box, so a good representation of what the condenser sees.

Static pressures are 118 at 94* ambient, overnight cold engine/system.

Idle @800 RPM after 1 min running.
LP=38
HP=180

5 min running idle 800 rpm
LP=38 HP=190
Vent temp = 53*
Accumulator = 54*
Evap in = 49* (read off of B-Nut on evap to line fitting, temp gun flush on nut)
Evap out = 45* (B-nut to accumulator)
Accumulator = (top 54*)

10 min total running time, 2000 RPM OAT 96
LP=32 HP=242
Vent temp =50.1
Evap in = 48
Evap out = 41
Accumulator = 48*

5 min at 2000 rpm OAT 98*
LP=33 HP=255
Vent 49.8*
Misted Cond
LP= 30 HP=225
Vent 48.2
tbirdtbird
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Re: 1995 Buick Lesabre

Post by tbirdtbird »

Those lows at 2K RPM are good, and the pipe in/pipe out of evap are good. Your core is cold. Vent should be lower. Has reheating been discussed?
Last edited by tbirdtbird on Fri Jul 22, 2022 1:40 pm, edited 1 time in total.
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tbirdtbird
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Re: 1995 Buick Lesabre

Post by tbirdtbird »

John, I am assuming he left, since he seems to have retired to east Texas. Anyway, I had issues with the engineering of the VA unit and I doubt he is involved with that at this point. I could be wrong, of course.

They had the frost switch and TXV setup to run a low side of 10 psi (hmmm who needs oil anyway). Core would drop below freezing, then comp would cycle off for a long time until core hit 60, then engage comp again. The resulting AC was very inadequate. I made a few changes, but the diff on the frost switch s/b in my book more like 10, not 20. With my changes I have a low of 20-22, and the cooling band during operation is much wider, ie the comp OFF time has been reduced. Works well.

Next time I have it apart I am gonna open up the TXV more
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JohnHere
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Re: 1995 Buick Lesabre

Post by JohnHere »

tbirdtbird wrote: Fri Jul 22, 2022 1:31 pm Your core is cold. Vent should be lower. Has reheating been discussed?
I was thinking that as well. Cars that old usually have foam seals on the blend doors that are falling apart. I don't think this car has a hot-water valve. Could be that some air is sneaking in from the heater core and warming the cooled air a little.
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Mark86
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Re: 1995 Buick Lesabre

Post by Mark86 »

It doesn’t have a water shutoff on the engine side of the system. I replaced the heater core hoses last year (painful) and there is no valve. These model Buicks use a engine vacuum and a pot to supply vacuum to controller under the glove box. They are notorious for failing, usually identified as defrost being the only vent to blow air (default). My modes are all functioning fine. Sometimes when pulling a hill, or passing, the air diverts half out vents, half out defrost, which I suspect is engine low vacuum. I tested the pot/accumulator and it held fine. The vac hoses under the hood were replaced last year. Found them to be brittle and flaking. Just installed new. The vac lines under the dash are unverified.

I could pinch off the heater hoses and report back

The HVAC fan is on the firewall / engine side, and I replaced that last winter when it just wouldn’t throw much air (original). New is working fine. It’s about 30” from the evaporator and not sure If I pulled the fan if I could do anything meaningful (cleaning) of the evaporator from that access. Next in line would be the heater core, which sits below ant to the side of the evap.

I’m not going to pull the dash apart, but will research to see where the actuator / lever for the blend door is and maybe see if I can verify it’s travel range.

On to the hose pinch test.
tbirdtbird
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Re: 1995 Buick Lesabre

Post by tbirdtbird »

"On to the hose pinch test."

Good idea
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