2007 LC A/C Suddenly Not Working - Advice Needed (6 Viewers)

[filer5000]

I did the rear a/c delete around 10 months ago and my air conditioning had been working great until a few days ago where it suddenly stopped working.

I did the basic troubleshooting steps I could, the pressure in the lines was good, and the high side pressurized to where it should, the clutch on the compressor worked (although it made a slight wrrring noise).
It sounds like it puts the tiniest bit of load on the engine and then goes back to idling after about a second or two.

Looking for advice on how to move forward.

 

[Rhetoric]

“Pressured to where it should” means what?

How much refrigerant is currently in the system?

Have you gone sniffing for any leaks?

Compressor clutch air gap in spec?

Throwing darts here but maybe this will get you started somewhere…

 

[filer5000]

“Pressured to where it should” means what?

How much refrigerant is currently in the system?

Have you gone sniffing for any leaks?

Compressor clutch air gap in spec?

Throwing darts here but maybe this will get you started somewhere…

Means that it has refrigerant and should start.

When the car is off, the low side sat around 50psi.

Not yet. Im thinking the caps I put on are culprit?

Could you tell me what this means?

Thanks. I appreciate it.

 

[Rhetoric]

Means that it has refrigerant and should start.

When the car is off, the low side sat around 50psi.

Not yet. Im thinking the caps I put on are culprit?

Could you tell me what this means?

Thanks. I appreciate it.

Air gap.

But I would wager you have a leak somewhere since the system has been modified.

Start sniffin'.

 

[filer5000]

Air gap.

But I would wager you have a leak somewhere since the system has been modified.

Start sniffin'.

Ill start sniffing and see what I can find. But it there was a leak, it wouldn't be sudden, correct?

Do you happen to know where I could find the normal pressure for both lines? Is there a chart or something somewhere?

 

[Aracobuilt]

Ill start sniffing and see what I can find. But it there was a leak, it wouldn't be sudden, correct?

Do you happen to know where I could find the normal pressure for both lines? Is there a chart or something somewhere?

If the leak is big enough it can be sudden or in less than one day.

 

[filer5000]

If the leak is big enough it can be sudden or in less than one day.

Air gap.

But I would wager you have a leak somewhere since the system has been modified.

Start sniffin'.

I did some testing tonight to see if I could figure anything out. Still at a roadblock and I am looking for help. Heres a few photos and videos I took just to give you a sense. A few things:
-The compressor wrrring isn't something I've recognized. Typically, it puts more load on the engine than it has been doing. My revs used to go from 0.5k to around 1.2k but not its like 0.5k to 0.7k.
-The cap on my high pressure side was never ziptied into place until tonight. Its possible it got the tiniest bit loose?? I want to say that it looks loose but I don't remember what it looked like when I installed it.



Compressor wrrring


High Pressure side cap

Low Pressure side cap

Let me know what you think... trying to figure this out before it gets hot again in my area.

 

[TenderTendon]

Your system is low. You should have 40-50 psi on the low side when the system is running. When the system is off and the the high and low sides have equalized, you should have well over 100psi on both sides (actual pressure dependent on ambient temp). High side should be 250-350 psi when running. There is a low pressure switch on the low side that is set at approximately 38 psi. It is there to prevent the evaporator coil from freezing and to protect the compressor. If the pressure drops below this limit, it will release the compressor clutch until the pressure rises above the limit again. That it why your engine speed only increases slightly for a couple of seconds, then goes back down. Your system is short cycling, due to a low charge. You have a leak. A leak at one of those flared caps would be my first suspect. If you don't have access to leak detection equipment, get a can of 134a with dye and a cheap UV flashlight. That will help you find it. You'll need access to a dark garage for this to work, unless you have a high power UV light, which isn't cheap.

 

[filer5000]

Your system is low. You should have 40-50 psi on the low side when the system is running. When the system is off and the the high and low sides have equalized, you should have well over 100psi on both sides (actual pressure dependent on ambient temp). High side should be 250-350 psi when running. There is a low pressure switch on the low side that is set at approximately 38 psi. It is there to prevent the evaporator coil from freezing and to protect the compressor. If the pressure drops below this limit, it will release the compressor clutch until the pressure rises above the limit again. That it why your engine speed only increases slightly for a couple of seconds, then goes back down. Your system is short cycling, due to a low charge. You have a leak. A leak at one of those flared caps would be my first suspect. If you don't have access to leak detection equipment, get a can of 134a with dye and a cheap UV flashlight. That will help you find it. You'll need access to a dark garage for this to work, unless you have a high power UV light, which isn't cheap.

Thanks for your input. This is greatly appreciated. I decided to use my leftover 3/4 can of R134a to fill it up to see if it made any difference and it seems colder. I think what you said is likely correct. Heres a few photos:

Original Pressure with car off.

Original pressure with ac running

Pressure after adding 3/4 can of r134a

Let me know if this means anything valuable. I'm headed to the store right now to buy some dye and some more r134a.

 

[TenderTendon]

Still low.

 

[filer5000]

Still low.

I added another can and the high was 300psi.

 

[bpalmer7440]

I added another can and the high was 300psi.

I have added three cans to our cruiser this year. At 93 F ambient the low got to 52 in Hg and the high got to a little over 300 in Hg. Prior to the last two cans the driver’s side would cool, but not the passenger’s side or rear. Now I could store ice cream in the truck.

 

[filer5000]

I have added three cans to our cruiser this year. At 93 F ambient the low got to 52 in Hg and the high got to a little over 300 in Hg. Prior to the last two cans the driver’s side would cool, but not the passenger’s side or rear. Now I could store ice cream in the truck.

Not sure if leaked again but when I drove it to work in 95° heat it took a good 15 minutes for it to be relatively tolerable. Do you think it needs more pressure?

 

[bpalmer7440]

Not sure if leaked again but when I drove it to work in 95° heat it took a good 15 minutes for it to be relatively tolerable. Do you think it needs more pressure?

I’ve done a few of these this year, and all of them have similar readings, with the larger interior vehicles pushing a little higher on the high end than the smaller vehicles. My understanding is that if the gauge pressures are sane then it is all about vent temperature. We had our car blowing 46 F at the vent. Is your driver’s side temperature different than your passenger’s side? If so then I would add more freon.

 

[TenderTendon]

Not sure if leaked again but when I drove it to work in 95° heat it took a good 15 minutes for it to be relatively tolerable. Do you think it needs more pressure?

Could be a few things... Condenser coil is partially clogged (it is almost 20 years old). Fan clutch needs attention/replacement. Charge is still low/still leaking. Charge is too high (doubtful, unless you added a few more cans). It would be a good idea to get a baseline of where you're at now. Check your pressures with the engine completely warmed up (so the fan clutch is engaged the best it can), engine speed at 1500-2000 RPM and climate control set to "Max Cool". It would also be nice to know how low your outlet duct temperature gets. Compare the duct outlet temperatures while it's running standing still at 2000 RPM (there should be an audible howl from the fan), and while it's on the highway doing 60 mph. If there is a big difference, your fan clutch is not engaging as good as it should.

 

[TenderTendon]

Double post. Sorry...

 

[TenderTendon]

I added another can and the high was 300psi.

What was the low side pressure during this time? What was the engine RPM? What was the approximate ambient temp? Is your drive to work stop and go, or on the highway? Sorry for so many questions..