Paging the AC gurus--need a second set of eyes on this. (1 Viewer)

[KliersLC]

Hi all,

I've dug around all (or most) of the AC threads and I think I know the answer to my issue, but wanted to run it by the experts.

2000 lx470, 240k, mostly stock. I bought it in feb 2020 and everything appeared to work fine. In roughly April 2020, I noticed that the AC did not blow cold. I used one of the autozone "pour in the cold" cans with no expectation of a good result, but the AC began working, and worked flawlessly until a few weeks ago. I did note that this past summer, the AC was not as strong as it had been before, but assumed that it likely had a small leak, and that is what had happened originally.

So when the AC stopped working this winter, I assumed that it had leaked out again. However, when I connected the autozone can, the pressures were too high--I don't remember the numbers, but they were in the red with two different gages. Conditions were mid 50s at ~50 feet above sea level.

I verified that the trinary switch is functional and shuts down the AC compressor when the pressure gets too low.

Current symptoms:
65 degrees ambient, 50ft elevations
-No cold air, but the cold hot blend functions correctly--I can get cold outside air and warm air as normal, just no "cooled" air
-AC compressor runs constantly--I observed it for 15 minutes and it did not cycle off.
- All AC lines on the passenger side at the firewall are all ambient temp as well as the lines at the condenser
-No refrigerant observed in the sight glass, but I did see a few bubbles when I was adding refrigerant one time, but then not ever again.
-The AC code displayed on the screen is code 21--solar sensor. I don't think this is the problem, as I don't get cold air when not in auto mode either.
-the condenser fan does not turn on, though I'm not entirely sure that I have met conditions for it to turn on--last I knew, it worked.
- I have not checked high side pressures

The way ahead:
-Based on previous posts, I think I have a blockage somewhere in the system, likely the expansion valve (but I'm not sure about this.)
-This appears to be beyond my capabilities to fix "correctly" as I don't have a vacuum pump, and can't properly evac the system.
-I'll likely take it to an AC shop, but if I can learn anything else useful here, I prefer to not write them a blank check to throw parts at it.

This smells a little like an issue I had with my 94 a few years ago, but in that case, the PO had added some r12 into the system somehow, and the expansion valve was apparently icing up. A new expansion valve, AC dryer and a fresh charge fixed the problem that time--I'm hoping for a similar result this time around.

Yet another AC question, but slightly different

Howdy, My 94 w/141k is having a bit of a problem on warm days >80. If it sits in the sun all day and I start it up anytime after 1 pm and before 6 or so, the AC will not work . If I drive it for a few minutes and then park it somewhere else for more than about 30 min, upon restart it will...

forum.ih8mud.com

Thanks all!

 

[3_puppies]

is the clutch engaged on the compressor?
it will be spinning as the belt is turning it but if the clutch isn't engaged it isn't doing anything
if the compressor is engaged but not doing anything, it could be a bad compressor
if there was a blockage after the compressor, the high preasure switch should shut the compressor off, similar to the low side
I wouldn't trust the guages on cans
you need a set of guages to watch the low and high side together
if the static charge preasures are good,
and no movement when compressor is on, it could be a bad compressor

without good #'s it is hard to say what is going on

you really have to want to put R12 into a system setup for R134A, connections are different, it is not impossible but not very easy to do.

 

[KliersLC]

is the clutch engaged on the compressor?
it will be spinning as the belt is turning it but if the clutch isn't engaged it isn't doing anything
if the compressor is engaged but not doing anything, it could be a bad compressor
if there was a blockage after the compressor, the high preasure switch should shut the compressor off, similar to the low side
I wouldn't trust the guages on cans
you need a set of guages to watch the low and high side together
if the static charge preasures are good,
and no movement when compressor is on, it could be a bad compressor

without good #'s it is hard to say what is going on

you really have to want to put R12 into a system setup for R134A, connections are different, it is not impossible but not very easy to do.

The clutch is engaged on the compressor--it is spinning with the belt and when the AC is disengaged with the button, the clutch stops spinning.

I also distrust the cans, but that is what I have.

That guy was definitely committed to putting the refrigerant that he had on hand into his truck...

 

[3_puppies]

I'm gonna take a WAG and say the compressor is bad
there is enough charge in it to make the clutch engage but you are not getting any cooling or seeing any circulation in the glass

 

[KliersLC]

Is there any way to test the AC compressor? I hate to throw parts at something without going through the troubleshooting steps to verify the bad part.

 

[Jeremy9A]

If you have high pressure on the low side, or close to equal pressures high and low, with no A/C both front and rear- the compressor is most likely bad. It's unlikely that you have a bad expansion valve both front and rear all the sudden.

 

[nissanh]

If your expansion valve is faulty you will still feel high temps on the discharge line going to the condenser.

Try taking off the drive belt and spin the AC clutch (not the pulley) by hand, it should gradually gets harder to turn if it builds pressure. with the age, and having dual AC, these compressors work too hard and could fail at your stated mileage. If you decide to replace the compressor, stay OEM new or GOOD used OEM, but not remanufactured as there is not a lot that can be fixed in a AC compressor other than the shaft oil seal and 2 big O-rings.

How to test a used AC compressor: Close the high side outlet by your finger and turn the clutch just 10 degrees and your finger should feel very high pressure.

 

[3_puppies]

Is there any way to test the AC compressor? I hate to throw parts at something without going through the troubleshooting steps to verify the bad part.

you need a set of guages,
you can get a set of guages, Harbour Freight has them, you need to see both sides of the system,
that will tell you what you need to know.

I wouldn't replace parts with out knowing for sure

 

[Scoin]

@KliersLC any update on what the fix was, I have the exact same issue on my 05 LC.

 

[KliersLC]

It was the Compressor for me. But the AC tech was a clown of the highest order.