Air Conditioning Issues on LX470 2002 (1 Viewer)

[BunduBasher]

Hi Crew,

I bought a LX470 2002 used and the A/C isn't working. I bought it sight unseen but had a mobile PPI done. At the time of inspection, the mechanic said the AC was working but honestly I have trouble believing that it would have crapped out during transport. Part of me wonder if the mechanic did a s*** job or knew the seller. That's besides the point now.

So I've been trying to figure out and isolate the cause of why the A/C doesn't work. I'm a very inexperienced self-taught mechanic, but I'm enjoying the process of learning as I figure this out. However, I could use your help to figure out what to do next.

When I try to turn the A/C on, the A/C light on the Nav screen flashes and it says check the air conditioner. It blows the normal air without A/C.

Here's what I've tried to fix it:
1) When I pressed the error codes, nothing flashes. Occasionally, I'll see 21 but that's because it's dark and the solar sensor isn't reading.
2) I've ran techstream diagnostics and flicked A/C sig on and off. Nothing happens.
3) I've hardwire around the magnetic clutch relay fuse, and that doesn't trigger anything.
4) I've checked one of the pressures with the A/C tank and pressure gauge that costs $25. It shows that it's filled, so doesn't look like it's low on Freeon.

Here's what I think is next, but please let me know what you think..
1) I was going to use a multimeter to see if I can check if the air compressor is shot. I have no idea how to do that, but I've read it around. If anyone has a great video of it, please share.
2) Bypass AC compressor - I'm not sure what that means or what it does. But I've been reading that is something else to do on the checklist.

Let me know if folks have any good advice on what else I can try. Thanks in advance!

 

[flintknapper]

Take it to a trusted A/C shop.

Not trying to be brash....but you clearly do not understand A/C and the components involved.

 

[cwmoser]

One thing you can do is look at the clutch on the AC compressor.
The Clutch is next to the drive belt.
Turn your AC off and observe that the Clutch is not moving.
Then Turn your AC on and observe that the Clutch is moving.
If you do not notice any difference, look for an electrical connection to the AC compressor.

 

[cwmoser]

I've got a 2002 LX470 too.
It has rear AC. Do you get cold air in the back?
Not sure if our LX470's were designed with independent systems but I do remember years ago having
a Dodge Caravan where the rear AC stopped working but the front AC worked properly.

 

[Smiles]

Take it to a trusted A/C shop.

Not trying to be brash....but you clearly do not understand A/C and the components involved.

Well said, I agree, but who am I to talk, I've only had 40+ years in the A/C trade.

Most folk that ask questions about A/C have got a steep learning curve.

But for my tupence worth, the best place to start is to check if theres any pressure in the A/C system, as thats what the problem is a good 80-90% of the time.

 

[SHIfTHEAD]

Yeah, I remove the service port cap on the low side and very gently push in the schrader valve to see if there is any pressure on the system. Usually it's very low or non-existent preventing the compressor from being engaged. If you have a leak then you'll need some equipment to find it, a freon detector (pretty cheap from Amazon) and if you're lucky it's just a bad oring. Once you sort the leak then you need to charge the system. Without gauges you can't do that properly, oh, and that's after you pull a vacuum on the system for at least 30 mins to fully evacuate the system (it's better to run the vacuum pump longer). Once evacuated you need to leave it and confirm the vacuum doesn't leak out, else you will just send freon out into the air again...

I've spent a fair bit of time learning what little I know and buying tools for a while now, and I'm still a total amateur. The principles are fairly simple, execution is difficult. And if you have a leak in something like the evap core, then your life is gonna suck or your wallet is going on a diet. Replacing them sucks. Bad. Way easier in something like an FJ60, but the new cars are practically built around the damn things.

 

[flintknapper]

Well said, I agree, but who am I to talk, I've only had 40+ years in the A/C trade.

Most folk that ask questions about A/C have got a steep learning curve.

But for my tupence worth, the best place to start is to check if theres any pressure in the A/C system, as thats what the problem is a good 80-90% of the time.

^^^^^

OP in his original post suggests he checked the pressure:

Quote: "4) I've checked one of the pressures with the A/C tank and pressure gauge that costs $25. It shows that it's filled, so doesn't look like it's low on Freeon."

However, it sounds as if he used one of those 'recharge' cans with a gauge on it to do so. Of course, without the compressor running he would have been reading only the 'static' pressure which for our purposes at this point would be almost meaningless. The exception being it 'might' tell us if there were enough pressure in the system to satisfy the Binary Switch so it would allow the the compressor clutch to engage.

I am happy to help folks (as I can) troubleshoot their A/C system....and have done so many, many times here, but in certain cases the expedient thing to do is simply take it to a shop, have them look at it and THEN if the owner wants to tackle the project, let us know and we can guide them through it.

Over the years.....I feel I've developed a sense for those who will (or will not) be able to reasonably work on their A/C systems. It's not black magic, but it DOES require a rudimentary understanding of how it works and why and in some cases an investment in the tools necessary to diagnose and work on it.

There is no shame is recognizing that at times, its best to take it to the experts.

 

[Smiles]

^^^^^

OP in his original post suggests he checked the pressure:

Quote: "4) I've checked one of the pressures with the A/C tank and pressure gauge that costs $25. It shows that it's filled, so doesn't look like it's low on Freeon."

However, it sounds as if he used one of those 'recharge' cans with a gauge on it to do so. Of course, without the compressor running he would have been reading only the 'static' pressure which for our purposes at this point would be almost meaningless. The exception being it 'might' tell us if there were enough pressure in the system to satisfy the Binary Switch so it would allow the the compressor clutch to engage.

I am happy to help folks (as I can) troubleshoot their A/C system....and have done so many, many times here, but in certain cases the expedient thing to do is simply take it to a shop, have them look at it and THEN if the owner wants to tackle the project, let us know and we can guide them through it.

Over the years.....I feel I've developed a sense for those who will (or will not) be able to reasonably work on their A/C systems. It's not black magic, but it DOES require a rudimentary understanding of how it works and why and in some cases an investment in the tools necessary to diagnose and work on it.

There is no shame is recognizing that at times, its best to take it to the experts.

Oooops, sorry I spoke.

 

[flintknapper]

Oooops, sorry I spoke.

All contributions are welcome, you've been here long enough to know that. So please...........

 

[flintknapper]

I've got a 2002 LX470 too.
It has rear AC. Do you get cold air in the back?
Not sure if our LX470's were designed with independent systems but I do remember years ago having
a Dodge Caravan where the rear AC stopped working but the front AC worked properly.

^^^^

Units with rear A/C are independent to a point (having their own lines, evaporator, TXV and controls) but they share the same compressor and thus the same refrigerant load. But what you allude to is certainly possible (one area of the vehicle cools while the other does not). IF there were an obstruction in a line, evaporator or TXV in either system for example, it would not perform while the other would continue to do so. So your question and point is a good one.

 

[gatormark91]

Hi Crew,

I bought a LX470 2002 used and the A/C isn't working. I bought it sight unseen but had a mobile PPI done. At the time of inspection, the mechanic said the AC was working but honestly I have trouble believing that it would have crapped out during transport. Part of me wonder if the mechanic did a s*** job or knew the seller. That's besides the point now.

So I've been trying to figure out and isolate the cause of why the A/C doesn't work. I'm a very inexperienced self-taught mechanic, but I'm enjoying the process of learning as I figure this out. However, I could use your help to figure out what to do next.

When I try to turn the A/C on, the A/C light on the Nav screen flashes and it says check the air conditioner. It blows the normal air without A/C.

Here's what I've tried to fix it:
1) When I pressed the error codes, nothing flashes. Occasionally, I'll see 21 but that's because it's dark and the solar sensor isn't reading.
2) I've ran techstream diagnostics and flicked A/C sig on and off. Nothing happens.
3) I've hardwire around the magnetic clutch relay fuse, and that doesn't trigger anything.
4) I've checked one of the pressures with the A/C tank and pressure gauge that costs $25. It shows that it's filled, so doesn't look like it's low on Freeon.

Here's what I think is next, but please let me know what you think..
1) I was going to use a multimeter to see if I can check if the air compressor is shot. I have no idea how to do that, but I've read it around. If anyone has a great video of it, please share.
2) Bypass AC compressor - I'm not sure what that means or what it does. But I've been reading that is something else to do on the checklist.

Let me know if folks have any good advice on what else I can try. Thanks in advance!

It's completely possible the seller put in a charge on a leaking AC just to pass the PPI. I'd ask the mechanic if he actually checked the charge pressure.

If you don't have a good set of manifold gauges, go buy some. You cannot realistically diagnose anything in the AC system without them. Less than $50 on Amazon.

If the AC clutch does not click when you turn on the AC, freon has leaked out or the AC compressor is locked, or the AC clutch speed relay senses a speed differential between the clutch and the engine. (This relay keeps a locked AC compressor from shredding the serp belt when the clutch engages). Also, check the wires to the speed relay on the compressor for wear, and make sure that the battery positive and ground terminals and the brass bar to the fuses are shiny and immaculately clean. Make sure the battery connectors are TIGHT TIGHT TIGHT. A poor ground or voltage issue can cause a voltage differential between the speed relay and the AC electronics in the dash. This will cause an AC error (it thinks the compressor is locked because it wrongly sees the the clutch and the engine are not turning at the same speed) and the AC clutch won't come on.

 

[Smiles]

All contributions are welcome, you've been here long enough to know that. So please...........

^^^^^^

Am I on the naughty step........

 

[flintknapper]

^^^^^^

Am I on the naughty step........

Are you ever off of it?

 

[gil12]

While we are on the AC topic, is there any reason to have a shop service any part of the AC system if it is working?

My 1999 LC has a measly 178k miles, AC front and back works ok, but the little view window always shows bubbles. I am pretty sure no work has ever been done on it. Am I okay to just let it run? (This is my preference, but my preference is often wrong.)
Gil

 

[flintknapper]

While we are on the AC topic, is there any reason to have a shop service any part of the AC system if it is working?

My 1999 LC has a measly 178k miles, AC front and back works ok, but the little view window always shows bubbles. I am pretty sure no work has ever been done on it. Am I okay to just let it run? (This is my preference, but my preference is often wrong.)
Gil

Aside from keeping the system properly charged with refrigerant, no.

IF your A/C system is currently providing you acceptable vent temps (for your location and needs) then give it no thought.

It is well to check the system pressures (high and low side) from time to time, but as far as 'preventative maintenance' is concerned, keeping your condenser and evaporator clean are about the only things you can do.

There are certain 'wear parts' involved (compressor, TXV, Condenser fan if so equipped) but typically these are run to failure or notable impending failure.

I'm not an advocate of using the sight glass as a diagnostic tool....despite what the FSM says. IF you read the FSM carefully about that, you'll find it contradictory. There are a number of reasons why you might see bubbles in the sight glass, some of them perfectly normal. And R134a refrigerant is especially prone to showing this anyway.

The sight glass reference IMO is a bit of a carry over from the R12 days when it WAS a useful tool. It could also help with a recharge (in a rudimentary way) IF you were way out in BFE and had no access to a set of manifold gauges, but beyond that..it is something to mostly ignore.