Air conditioning gurus needed (2 Viewers)

[Zooguy]

It was a little bit warm today after work. So I tried to turn on the air conditioning on my '99 Land Cruiser and it did not cool off at all. Outside temperature was showing to be 81*F and the soil temperature gauge I have mounted inside one of my vents was showing the same with the blower on high the temperature settings set all the way cold and air conditioning button turned on. I don't see the compressor kicking on.

Where to start? When I turn on the button for air conditioning the light comes on but nothing happens.

Is there a fuse that I can check? I doubt that's the issue because the light is coming on when I push the AC button but I don't know where to begin

 

[nissanh]

Is thsi the first time you turned on AC for this year?
using a Test light check whether you get the AC compressor signal at the AC fuse when engine is running and AC button is pressed in.
If that is good, check the clutch with a resistor to see it has continuity.
See the wire from the fuse to the clutch wire plug is not broken.

 

[Bisho]

You should check your refrigerant pressure first. If you do not have enough R-34 in the system, the pressure switch will inhibit the clutch from engaging to protect the compressor.

 

[Zooguy]

Is thsi the first time you turned on AC for this year?
using a Test light check whether you get the AC compressor signal at the AC fuse when engine is running and AC button is pressed in.
If that is good, check the clutch with a resistor to see it has continuity.
See the wire from the fuse to the clutch wire plug is not broken.

I know it sounds dumb but I wasn't able to locate the AC fuse whenever I was looking around the truck it wasn't under the hood behind the battery or down by the driver's feet. Could you tell me where it's at please so I can check.

I did unplug what I believe was the pressure switch. Behind the grill on the driver's side very close to the transmission cooler. Poking around on that with my multimeter and some jumper wires from the battery I was able to get my electric fans to turn on but that's it.

 

[vipergrhd]

You really need to get some gauges hooked up and see if the system is empty.

 

[Zooguy]

You really need to get some gauges hooked up and see if the system is empty.

yes i do ... i did take the caps of the ports and on the low side when i poked the valve in the port just a tiny bit of air came out then so oily liquid sprayed .... on the high side it just seemed like a lot of air/pressure and no thing else

 

[Moparsncruisers]

As others have already suggested, check pressures 1st!

 

[Zooguy]

Hooked up a pressure gauge and low pressure side was reading 100 PSI without the compressor running. With the vehicle turned off using a power probe we fed 12 volts to the clutch wire and the clutch would work that way so now I'm thinking potentially a problem with the relay.

The mechanic I took the Land Cruiser over to said 100 PSI seemed a little low but should have been enough to kick on the system. A second mechanic I spoke to who is a shop manager at Alexis dealership said 100 PSI on the low side seemed a little bit high ...

So now I'm still extremely confused but at least I know the clutch is is able to function with 12 volts does anybody know where exactly the relay is for me to inspect

 

[Eyedaho]

I had the same thing last year, and just needed a half a can of refrigerant. As others have said, I would start there. I have all of the parts on hand to fully rebuild my system, but I haven't had any issues since last year.

 

[oldmxdog61u]

100 at the low side is pretty high. Be careful on the high side as it can be >>100’s. Wear nitrile gloves and eye protection, not to sound like your mommy. Echo here, amazon has a nice vacuum pump and gage set on sale for $110. Will save you a lot more over the long run as it will save you from blind addition of coolant that has moisture in it from just pushing it in.

 

[Moparsncruisers]

You're only looking at static pressure, 100psi without the compressor running is fine but you need to see what low and high side are reading with the clutch engaged. If it won't engage then you'll need to have it evac and recharged, that's the only way to verify it has the correct charge amount in there. Without doing that it's all guess work!

 

[Zooguy]

Okay well checked the relay and it's fine .... With the the A/C BUTTON PUSHED, blower on high, i used a wire to jump 12v from the battery to the relay socket and the clutch works fine and blows cold ...

So the "m i r h t r" mirror heater? Relay is directly next to it same part number so I flip-flopped them still not working


Soooooo what would be the next step to check and test.

 

[shtbrwn86]

Like others have said, you are likely low on refrigerant. I am pretty sure there is a test you can do with the hvac controls that will display an error code that tells you if the low pressure switch is not engaging? If it is low, you likely have a leak. What you do from there, is up to you. If you think the system has been serviced before you could get a UV penlight and poke around under there. You could also just go get an evacuate and recharge done. It will cost like $200 but it's possible the leak is very small and maybe this recharge will last you years.

 

[shtbrwn86]

Take a look at the PDFs in this thread for the trouble code procedure.

AC Diagnostic Help Please

Last week the AC in our 99 LC started acting up. It occasionally only blows hot air and at other times it works fine. We took it the dealership to have the AC recharged and it turned out the AC was nearly fully charged. As the technician started to wrap things up, the LC started blowing...

forum.ih8mud.com

 

[Rgill]

This chart is engine running AC clutch engaged. This is a baseline chart for R134 if your low side is less then 25lbs the low pressure switch will cut off the AC clutch if the high side goes to high a high pressure switch will also cut off the AC clutch. With engine off the low and high sides will equalize if they do not then you have a problem. This is a start. There are some really good troubleshooting charts on line showing how to read the gauges to isolate a problem. Typically a plugged system, bad compressor or both.

 

[Moparsncruisers]

This chart is engine running AC clutch engaged. This is a baseline chart for R134 if your low side is less then 25lbs the low pressure switch will cut off the AC clutch if the high side goes to high a high pressure switch will also cut off the AC clutch. With engine off the low and high sides will equalize if they do not then you have a problem. This is a start. There are some really good troubleshooting charts on line showing how to read the gauges to isolate a problem. Typically a plugged system, bad compressor or both.
View attachment 3573942

Yeah that chart is not accurate.....

 

[Rgill]

Yeah that chart is not accurate.....

It is a general base line for R134 and the properties of R134 fall into this chart.

 

[Moparsncruisers]

It is a general base line for R134 and the properties of R134 fall into this chart.

Do you do a lot of AC work?

 

[Zooguy]

okay everyone ... my problem is the switches are all on and set to cold .... THE CLUTCH IS NOT COMING ON!!! i cant check pressures correctly with out the clutch working. .... with a power 12v feed to the relay socket or a power probe directly to the wire going into the clutch it comes on. ... I do not want to run like that for more than just a moment because obviously there's another safety feature of some sort or sensor not allowing it to come on. I don't want to do anything that would cause further damage of the system by overriding all the safety features.

 

[Moparsncruisers]

okay everyone ... my problem is the switches are all on and set to cold .... THE CLUTCH IS NOT COMING ON!!! i cant check pressures correctly with out the clutch working. .... with a power 12v feed to the relay socket or a power probe directly to the wire going into the clutch it comes on. ... I do not want to run like that for more than just a moment because obviously there's another safety feature of some sort or sensor not allowing it to come on. I don't want to do anything that would cause further damage of the system by overriding all the safety features.

You need to do an evac and recharge, that's the only way to verify the system has the correct refrigerant charge. After that is known and it's still not working then the diagnosing can begin.