No AC air conditioning Bad Sun Sensor
 

The ac is not working. The compressor will not come on and the radiator fans do not come on. The fuses and relays are all okay. So I ran the climate control self check and the sun sensor has an open circuit or short. Does anybody know if this bad sun sensor prevents the ac from working?

Take care of that SVX,

John

I would make sure...
 

the system is properly charged with refrigerant. (You may already have)
Would not suspect the sun sensor, but everything is possible.
Could be a several things. Bad clutch on the compressor? Probably unlikely.
I would go for the low refrigerant level first. again, you may already have done the test on that.
Good luck,
Keith

Do you have something sitting on top of the sensor, like a parking pass?

Not sure if this applies to the SVX, but Toyotas will set a code for the sun sensor when they are in the shop, due to the fluorescent lighting, so if you're inside, that may be what's doing it, although I don't think that a bad sun load sensor would keep the AC from working at all.

I have just checked my JDM SVX. When defrost is selected and operates, hot air is not discharged unless the temperature control is set to a figure above ambient. If the setting is below ambient, only cold air is discharged.

I can only presume that this is the normal arrangement, even though it does nor appear logical. This could well be causing confusion in respect of what has been considered as a fault.

I am not sure how to check the pressure. The instruction I have say to run the compressor for 5 min's and then check the low pressure side. Well my compressor isn't running so..... any idea what I do about that?

Does the compressor not work if the pressure is low? A low pressure cut off switch?

Is there a way to kick the compressor on?

Nope. It's all clear up there.

Yours is working just fine. That is what it supposed to!!! Have you ever checked the climite control computer with the self check? I like the way it does it.

John

The most likely cause would be low on refrigerant, low pressure. Are you aware there is a full and complete AC troubleshooting section in the How-To above? That will inform you what to look for.

Regards the sunload sensor, you will get this code every time you run the diagnostic and you don't have strong sunlight shining on the sensor [but a strong 100w bulb [high heat energy] shining near it will do the equivalent]

Running that test in low light will nearly always throw that code.

Joe

The "how to" I printed out does not say how to check the refrigerant level at all.........as far as I can tell.

To chycec the presure...
 

You need to get some gages and fasten the hose on the lo side to see if any refrigerabt is in the systm. then get back to us with the information.

We can help you from there.

Keith

Yeah John, Keith is right.

If you look at page 8 of the AC how-to, you will see what it suggests may be wrong if the compressor clutch does not engage, which is the symptom you have.

It suggests checking fuse 15 is OK, so I expect you will have seen to this.

Without saying how to do it, it says refrigerant level may be low and should be checked. The only way to check this is to put gauges on to the high and low connectors, and see what pressures you have.

Back at the top of the document it shows the range the pressures need to be at.

In order for the correct pressures to be there, it requires that the correct amount of refrigerant is in the system. They give this amount in fluid ozs I think.

AC engineers will know from how low your pressure is showing what percentage [or ozs if you like] of refrigerant needs to be added.

I'm not that expert, so I can't help you there, but that's how it is done. Usually, though, they add some gas with dye first, and watch for system leaks. No point filling it up if you need to fix a leak first.

Joe

Okay the the climate control computer checks out okay. No sun load sensor error now that the sun is shines on the dashboard!!!! I know I have read about this in the past post so I am not the only one to test this computer in the DARK.

My A/C was leaking when I got the SVX back in 2000. At that time I had the "Leak dye" added. It has been cold ever since then.

Last year I thought it was having trouble keeping up but the pressure checked okay.

The gauge I have borrowed looks like a tire gauge with the stem that pops out to read pressure. It is set up just for the low pressure side. They say to use the gauge only after running the compressor for five minutes.

What I do not know is if the low pressure changes when the compressor is running.

Well any way I was busy last night I had to change a coil that went bad yesterday. The one in the back on the left side. Went well only 1-1/2 hrs to find the used one and put it in.

Take care of that SVX,

John

The pressure doesn't really change all that much. It stays right around 40PSI (at least, that's what I got on a 70 degree day). If you just get a can of refrigerant with a pressure gauge already, all you have to do is empty the can in until you meet the correct pressure in the system. It should take about 21-25oz of R134. If your are is equipped with R12, that's going to be a problem because they don't really sell R12 anymore.

Probably the easiest way....
 

to charge the system is making note of the frost on the low side line.
Of course, the engine has to be running and the air conditioner turned on to cold (real cold.)
If the compressor clutch doesn't engage because of the low pressure switch, adding refrigerant will increase the pressure and make it come on.
If the compressor clutch engages and starts pumping, you should get some frost developing on the low side line as you charge the system with the refrigerant. If you should over charge it, the high side safety will cause the clutch to disengage. and clutch will go on and off as the pressure in the high side fluctuates, then just purge it a bit.This is of course, after the frost has began to develop. It would be possible for the low side safety to disengage the clutch with the system undercharged, because of the engaged compressor clutch pulling the pressure down too quickly. (not likely, but possible) If you have frost on the line, you are probably getting close.
Pressure in the system will vary a lot when it begins cooling because the high pressure side gets pretty hot and expands the gas. (refrigerant)

It is possible to get R12.
Real costly. A few years back it was $20.00 for 30 lbs. Now, since the Gestapo, US Government), got into the game, it now is about $1,400.00 wholesale for 30 lbs.
However R414A is a direct replacement for R12 with no problems...and more readily available. (what I use) "just pour it in".
Hope this helps,
Keith