Automotive Air Conditioning Information Forum

I have a 2015 Toyota Land Cruiser that has a good AC until you hit slow driving conditions after being driving for 45 minutes to one hour in traffic with outside temp of 80ish degrees, then the AC stops blowing cold air and only blows warm air. After about 30 to 35 minutes it goes back to cold event is still in traffic.

When the AC stops working, the AC compressor stops working as well and does not cycle and the hoses/pipes with refrigerant in the engine compartment are warm with no sign of ice at all.

I have taken it to Toyota and they can't figure out what is wrong. The air cabin filter is new and Toyota flushed and re filled the AC refrigerant with no luck. I know I can take back to Toyota but last time spend at the dealer one week and it is still not fixed. What makes it more difficult is that it is an intermittent problem and only happened after a long drive

Any assistance greatly appreciated

You know how the clutch gets sucked in towards the compressor pulley when the a/c turns on? Try hitting/tapping/pushing it with a broom handle or something towards the pulley, to try to "help it" pull itself in. BE CAREFUL you are poking around with pulleys and belts. I'm thinking you have a weak clutch coil and/or power going to the clutch coil. The hotter the coil gets, the less magnetic it becomes once energized. I'm thinking in traffic the added engine bay heat, makes it that once it cycles off briefly, it doesn't have the power to pull the clutch back in to turn on.

On a side note, sorry you had to deal with dealership. In my experience they really have no diagnostic skill and just throw things (expensive things, labor/parts) at a problem hoping it would go away, without a clue how systems work. Sure there are some people that work there that know what they are doing, but i've never run into any of them.

Since when the a/c does turn on, it does work well, any decent mechanic would know that we are looking to find out what and why it wont turn back on (an electronic issue). We know once its on, physically the system works well.

Thank you for the reply and your time. The broomstick trick did not work..

Few days ago we took a 6 hours drive in the truck. On the way to the destination it was quite cool (60s) so the AC performed perfectly. The entire time the traffic was moving quick so I never got stuck in traffic.

On the way back the drive was also 6 hours but the outside ambient temperature was significantly higher high (80s)The AC work fine until hour 5 1/2 when we got stuck in traffic. Then the AC stopped working and started blowing warm air till we reached destination.

Seems that when the truck stops or significantly slows down the AC stops working but if I start driving and get in traffic right away I get about one hour of cold air...

I hope this help with any ideas...

Thanks

bbbsti ltd wrote: The broomstick trick did not work.

OK, so the AC clutch stops engaging when things get too hot, like in traffic. Proved by the broom handle test. So - if all your fans/fan clutch are fine, then possibly the AC clutch gap is too wide (broom test); some AC clutch can have a pacer removed to make this gap more narrow and then operate correctly.

Sorry, I meant hitting the compressor with the broomstick didn't make a difference..... maybe not enough space to hit the clutch plate right.

But the correlation with the temperature you gave seems correct. When all is working fine a vent thermometer register 40F degrees.

Do you have gauges? I would be curious to see what pressures you are seeing. Would take a lot of the guess work out.

My new thought is simply air flow/condenser efficiency. Low speed = low air flow = higher high side pressures, possibly so high to send a too high pressure signal to the ecu, which in turn stops voltage going to the compressor clutch, turning off the compressor. Possibly it has a time out? Meaning once its tripped it takes a while before it will try to kick the compressor back on again.

Obviously normally this shouldn't happen. So you need to make sure of a few things. That all shrouding around the radiator and on the sides of the radiator and condenser are intact. You need to make sure that the condenser and radiator are clean on the exterior. Also you must look IN BETWEEN the two. I've seen leaves and plastic bags and stuff in there seriously hindering the flow. remember air must flow through the radiator first from the fan sucking on it, THEN pull air through the condenser. Do not assume you have good air flow from your fan just because the coolant temperature stays normal. For one the coolant gauges in cars show the same under a wide variety of temperatures so people don't "freak out" when they see the gauge move. Also the radiator needs far less air flow than the condenser to keep temps in check. So you need to check your fan clutch. A few things your fan clutch SHOULD do. When you first start your truck after sitting over night rev the engine to about 2k - 2.5k rpm or so, the fan should ROAR loudly, like a big rig truck, keep the rpm there, after several seconds to a minute later, it should get very quiet. What you heard was the fan in lock up mode, where the fan is spinning about 80% of the speed of the pulley. Once it gets quiet, its spinning around 30% of pulley speed. Now you know what to listen for. Once the engine is good and hot, especially if you have been at idle for awhile in traffic ext. if you put it in neutral (helps to be in a quiet area) and rev the engine to to about 1500 rpm or a little less. You should hear that roaring noise and then again if you hold it there after a few seconds it will either stay the same or quiet back down. All these fan clutch tests are most obvious when your head is right there with the hood open. the amount of air flow from locked/unlocked at slight reving, and the noise, is unmistakable. ALso when the truck is good and hot, idle it for a minute or two. then look under the hood while someone shuts off the truck. the fan should stop very soon after the engine only a few revolutions (indicating good, that it was in lock up mode) it should not coast slowly down to a stop like an electric fan would. Another thing you can do when the engine is good and hot and has been idling a minute or so, is to CAREFULLY try to slowly the fan with something like a rolled up newspaper. It should not be able to be stopped, if it seems like its only the weight of the fan blades momentum, and nothing really powering it strong turning it, your fan clutch is shot and needs replacement. Check for oil/dirt sticking to an oil leak on the fan clutch also, thats another failure indication. The AISIN brand is preferred on the aftermarket. Fan clutches are a wear item, and if i remember what i read only last 30-50k miles. Best bet is just do the tests.

Also another thing you can do is swap your a/c clutch relay with another relay. If you look close i'm sure your truck uses another one of the same relays some place else, just switch them. Its possible, that under high soaking engine heat, the relay is failing to work correctly.

Again with the heat killing electronics its possible the compressor clutch coil itself is just getting really weak at high temperature. When the a/c should be working and its not, it would be very telling if you could check the voltage going to the cluch, or rig up a "vampire" clip to the cluch coil wire and have the other wire lead up in the engine bay where you can get to it, but make sure its not grounded. then when the a/c kicks off you can pop the hood and quickly hook up a test light and see if the a/c compressor coil is getting voltage, if so you just need a new coil or the connection is no good.

Thing is, a clean radiator/condenser, and properly working fan clutch is something you should have anyway, so def do that first. You will figure it out-don't give up.

Compliments of http://www.rockauto.com and HAYDEN the mfr of fan clutches. This is not an advertisement for them, I wanted to site where I am getting the image and its creator.

Start by checking & adjusting the compressor clutch gap. It is the most likely culprit, and adjusting one with 3 years of wear is never a bad thing.

With the engine cold, use a feeler gauge to check the gap. Anything over .025 inches is not good.

Don't have a feeler gauge? Use a few business cards. No business cards? Tear off a chunk of that cheap cardboard box your K-Cups come in. That cardboard is .017 thick.

If you can get 2 or three pieces of that stacked up in the gap, you need to adjust. The gap can be as small as .005, as long as it does not drag.

The actual adjustment depends on the vehicle. Some compressors have shims behind the clutch plate, Some use a special tool to press the plate on the shaft. Many times a special tool is needed to remove the clutch plate to access the shims.

A factory service manual should have the procedure. Mitchell sells 1 month subscriptions to the FSM for under $20 That will get you the entire electrical schematic as well as the troubleshooting tree for your exact vehicle.

bohica, the OP stated he tried pressing on the center plate of the a/c compressor, and the compressor still didn't engage. Checking the gap is a good idea, but I think a multimeter/test light/ and some gauges could go a really long way in narrowing this one down. He should try the broom handle clutch gap thing again making sure he is pressing on the right thing and hard enough b/c the first time he was a little doubtful.

Please STOP telling people to jam solid objects in to accessory drives on running engines.

I have see what happens when a screwdriver was used to "tap" a clutch - took out a radiator and the hood. Could have killed the guy that tried it.

Check & adjust the clutch gap. No need to do dangerous tests, or check a bunch of electrical parts. The normal failure is the gap - it wears with use. When you hear hooves, think horses - not zebras.


As far as jamming something in a running fan...


http://www.autoacforum.com/messageview. ... adid=10772

That is the proper test for fans.

.