A/C suddenly stopped working on 100 series: advice. (1 Viewer)

[bobr1]

Hello,

I was just driving around and my A/C stopped working this afternoon. It has been working great all summer and even yesterday. No slow change in A/C performance, it just totally stopped blowing any cold air this morning when I started it up and drove around. Just trying to get ideas on where to start to try an diagnose the problem. Also, I wasn't hearing the A/C pump engaging either. I appreciate any advice on this.

2000 LC 122,000 miles.


Thanks,

Bob

 

[flintknapper]

Bob you'll want to begin by physically looking at the compressor (hood up, engine running, AC on) to see if the compressor clutch is engaging or not. IF not (and it sounds as if it isn't) then we will need to move ahead to searching out the reason(s) why (most likely electrical).

 

[CORunner]

I went through something similar last year. My system suddenly stopped working. Ended up being a leak in the line going to the rear AC. With no freon/refrigerant the system won't even try to come on.

Other culprits could be:
- Fuse
- Relay (which would be a major pain because it isn't replaceable. It is hard wired into main junction block)
- AC clutch

 

[bobr1]

Bob you'll want to begin by physically looking at the compressor (hood up, engine running, AC on) to see if the compressor clutch is engaging or not. IF not (and it sounds as if it isn't) then we will need to move ahead to searching out the reason(s) why (most likely electrical).

Yeah, I looked under the hood and the clutch wasn’t engaging and disengaging, it looked like it was spinning the entire time so I guess it’s engaged.

 

[flintknapper]

Yeah, I looked under the hood and the clutch wasn’t engaging and disengaging, it looked like it was spinning the entire time so I guess it’s engaged.

Well....we need to know one way or the other. IS it engaged or not? Can you feel the high and low side lines for us (high side is the smaller line, low side the larger line). High side should be warm to hot, low side (hopefully) cool to cold. IF both are ambient then the compressor is not engaging or you've lost your refrigerant charge.

I don't mean to sound curt....its just that we need a good starting point.

 

[3_puppies]

is the blower still moving air out the vents?

 

[bobr1]

is the blower still moving air out the vents?

The blower is still moving air. And when I turn the thermostat up to heat the heat works

 

[Africaster]

Exactly same thing happen to us 2 months ago in Atlanta GA … no aircon in 100+ temps was no fun … was in the wife’s Q7 but same symptoms … turned out to be the blower motor … easyish DIY replacement ——- ignore, just read your post that the blower still moves air

 

[flintknapper]

The blower is still moving air. And when I turn the thermostat up to heat the heat works

Bob, go back to post #5. We need to establish whether or not the clutch is engaging. If you are unsure what to look for...post a video and we can tell you. This will give us some direction.

IF the clutch is engaging and the lines are as described above, then you might only have a problem under the dash. IF it isn't engaging then we need to determine if its an electrical problem, mechanical problem (clutch/compressor) or issue with the refrigerant charge.

Is this something you are willing/capable of doing yourself? IF not...then just take it to a shop. There are so many things it could be (at this point)....so without more information/investigation it is all speculation as to what is the cause. Get busy one way or the other, get us some info or get it to a shop.

 

[bobr1]

Bob, go back to post #5. We need to establish whether or not the clutch is engaging. If you are unsure what to look for...post a video and we can tell you. This will give us some direction.

IF the clutch is engaging and the lines are as described above, then you might only have a problem under the dash. IF it isn't engaging then we need to determine if its an electrical problem, mechanical problem (clutch/compressor) or issue with the refrigerant charge.

Is this something you are willing/capable of doing yourself? IF not...then just take it to a shop. There are so many things it could be (at this point)....so without more information/investigation it is all speculation as to what is the cause. Get busy one way or the other, get us some info or get it to a shop.

Sorry, been crazy busy. I found that the Freon level was low after checking the pressure. I added freon and the compressor clutch started working again and now it is blowing cold air again. I'm sure it is a small leak, but I do not have the time right now to fix it. Thanks for the help.

 

[flintknapper]

Sorry, been crazy busy. I found that the Freon level was low after checking the pressure. I added freon and the compressor clutch started working again and now it is blowing cold air again. I'm sure it is a small leak, but I do not have the time right now to fix it. Thanks for the help.

Glad you got it sorted out. IF it's a small leak (top off refrigerant once a year) it isn't worth chasing down. IF its more serious than that....then at some point you'll want to find and fix the leak(s).

 

[ad nave terram]

How can you tell whether the freon level is low?

 

[flintknapper]

How can you tell whether the freon level is low?

Set of Manifold Gauges to read both the high and low side pressure. IF both sides show low pressure (for the ambient temp) then odds are...you are low on refrigerant.

IF the compressor will not come on at all....then you can still use the gauges to read the 'static' pressure which will tell you if there is enough pressure (or not) to satisfy the low pressure switch (binary switch) which would otherwise prevent the clutch from engaging.

 

[ad nave terram]

Set of Manifold Gauges to read both the high and low side pressure. IF both sides show low pressure (for the ambient temp) then odds are...you are low on refrigerant.

IF the compressor will not come on at all....then you can still use the gauges to read the 'static' pressure which will tell you if there is enough pressure (or not) to satisfy the low pressure switch (binary switch) which would otherwise prevent the clutch from engaging.

Thank you!

 

[bmxben]

Set of Manifold Gauges to read both the high and low side pressure. IF both sides show low pressure (for the ambient temp) then odds are...you are low on refrigerant.

IF the compressor will not come on at all....then you can still use the gauges to read the 'static' pressure which will tell you if there is enough pressure (or not) to satisfy the low pressure switch (binary switch) which would otherwise prevent the clutch from engaging.

flintknapper - I have a similar but different problem, no AC, compressor not engaged, the relay is good, confirmed clutch is good with a wire jump, the ambient temp is reading -22 degrees, replaced ambient sensor - remains at -22 degrees. I am avoiding the possibility of it being my HVAC panel/AC amplifier. I will be checking free on levels after work.

*EDIT* I have done a lot of searching and oddly enough this is the first I have read about low free on defaulting to disengaged clutch

 

[flintknapper]

flintknapper - I have a similar but different problem, no AC, compressor not engaged, the relay is good, confirmed clutch is good with a wire jump, the ambient temp is reading -22 degrees, replaced ambient sensor - remains at -22 degrees. I am avoiding the possibility of it being my HVAC panel/AC amplifier. I will be checking free on levels after work.

*EDIT* I have done a lot of searching and oddly enough this is the first I have read about low free on defaulting to disengaged clutch

^^^^

There is a Binary Switch (pressure switch) inline with the system that will not allow the AC compressor clutch to engage IF there is too little pressure (approximately 30 psi) or too much pressure (around 400 psi). You can jump past it if you suspect it is bad.

IF the system has not been serviced recently and the system pressure unknown....its a good idea to start there. Put a set of manifold gauges on the system and read the 'static' pressure. The reading should be roughly equal on both the high and low side gauges, since the system is not running and pressures have (or should have) equalized.

The pressure will vary with ambient temperature (outside temp). But lets say it was 75°F outside when you tested the system. The Saturation pressure for R134a at that temperature would be about 78-79 psi, which indicates two things.

1. You have enough pressure to satisfy the low pressure side of the binary switch and allow the clutch to engage.
2. You have some amount of 'liquid' refrigerant in the system (though we can not tell now much with a static reading).

 

[bmxben]

^^^^

There is a Binary Switch (pressure switch) inline with the system that will not allow the AC compressor clutch to engage IF there is too little pressure (approximately 30 psi) or too much pressure (around 400 psi). You can jump past it if you suspect it is bad.

IF the system has not been serviced recently and the system pressure unknown....its a good idea to start there. Put a set of manifold gauges on the system and read the 'static' pressure. The reading should be roughly equal on both the high and low side gauges, since the system is not running and pressures have (or should have) equalized.

The pressure will vary with ambient temperature (outside temp). But lets say it was 75°F outside when you tested the system. The Saturation pressure for R134a at that temperature would be about 78-79 psi, which indicates two things.

1. You have enough pressure to satisfy the low pressure side of the binary switch and allow the clutch to engage.
2. You have some amount of 'liquid' refrigerant in the system (though we can not tell now much with a static reading).

It works! So after going through fuses, relays, amplifiers, control units, check freon levels, high-low pressures, pressure switches, and endless voltage checks it came down to a part I have seen nobody mention, anywhere, practically ever. In fact, I have found one formal mention of it here on mud. Behold the "smoke sensor."
I was poking around doing voltage checks in the front of the radiator, wanting to trip the condenser fan just to see it work, grasping at straws and I unplugged this component by accident, its harness met the same pigtail as the fan, and with the lack of light, I grabbed it instead. Because I leave the AC system on when poking around, after unplugging it, the whole system kicked on, my ambient temp corrected from -22 degrees to the accurate 70 degrees (December in texas), and the system ran ice cold. Also should note that the heater ran hotter as well. I will attach a picture below and put in the part number in hopes this will help someone else in the future. My problems we sudden and had zero symptoms other than working on one moment and then not the next. I will not be replacing or cleaning this part.
From my understanding, there isn't much info out there, this part came on all of the LX470s and didn't start to make an appearance on the LC100 till 2001.

Part number: 88898-60020

The second image is how it should be seen in front of the radiator.

Thank you to everyone, I learned a lot through all of this.

 

[TLCJC]

It works! So after going through fuses, relays, amplifiers, control units, check freon levels, high-low pressures, pressure switches, and endless voltage checks it came down to a part I have seen nobody mention, anywhere, practically ever. In fact, I have found one formal mention of it here on mud. Behold the "smoke sensor."
I was poking around doing voltage checks in the front of the radiator, wanting to trip the condenser fan just to see it work, grasping at straws and I unplugged this component by accident, its harness met the same pigtail as the fan, and with the lack of light, I grabbed it instead. Because I leave the AC system on when poking around, after unplugging it, the whole system kicked on, my ambient temp corrected from -22 degrees to the accurate 70 degrees (December in texas), and the system ran ice cold. Also should note that the heater ran hotter as well. I will attach a picture below and put in the part number in hopes this will help someone else in the future. My problems we sudden and had zero symptoms other than working on one moment and then not the next. I will not be replacing or cleaning this part.
From my understanding, there isn't much info out there, this part came on all of the LX470s and didn't start to make an appearance on the LC100 till 2001.

Part number: 88898-60020

The second image is how it should be seen in front of the radiator.

Thank you to everyone, I learned a lot through all of this.

View attachment 3191520

View attachment 3191521

Do you have a photo of where the smoke sensor is located in engine compartment? Also did you just leave it unplugged for AC to work or remove it entirely? Thank you. My 1999 LX470 is having issues.

 

[bmxben]

Do you have a photo of where the smoke sensor is located in engine compartment? Also did you just leave it unplugged for AC to work or remove it entirely? Thank you. My 1999 LX470 is having issues.

It’s right in the front of the radiator, you can just unplug it, I removed mine to investigate it, but you can leave it mounted.
Unfortunately I don’t have the LX anymore, more unrelated problems occurred. Here is a picture of the module. It’s on the outer side of
radiator.

 

[flintknapper]

Do you have a photo of where the smoke sensor is located in engine compartment? Also did you just leave it unplugged for AC to work or remove it entirely? Thank you. My 1999 LX470 is having issues.

I am uncertain if failure of this sensor interrupts the circuit or not (don't have electrical manual in front of me) but the sensor is essentially an 'Air Quality' sensor.

IF it detects smoke/smog/poor quality air it will switch the HVAC system from outside air (if already selected) to recirculate.