Need Air Conditioner Help-HOTLANTA!!!

[AutoXsi]

Man, is it hot without an AC working. I've tried searching several times on this and other 240 forums. Even tried googling the issue. I've got a 96' 240sx SE.

My AC blows out cold air in the morning and at night only(would seem it works only when it's 80 degrees and below). However, when the temps are in the 90's and up, the AC blows out hot air. What I found weird was when I opened both sides of the windows during the hot temps outside, the AC system would become cool for just a couple of minutes. Kind of weird, wondering if there is a temp sensor inside the car. The clutch on the compressor clutch comes on when the AC button is pressed and off when depressed. I can also feel the relay under the hood for the clutch click/move when the ac clutch is in-gauging. I filled it up with a can of freon and still no fix. I also tried a can of AC oil and some uv dye to detect for a leak for the past couple of weeks. Keep in mind, I used a gauge to messure how much pressure is on the high and low side, just to be within factory spec. I have the FSM and checking through all the diagnostics. I do have a few questions about some parts and what they do. Any help from the AC experts would be greatly appreciated.

There is a triple-pressure switch on the liquid tank. I'm not sure if this tells the AC system to activate.

Also, there is an Ambient Temperature Switch in between the front bumper and condensor. What does that do? Does it have anything related to cutting the system on/off?

[ATLspeed]

the ambient temperature switch determines how cold the ac will blow

[AutoXsi]

the ambient temperature switch determines how cold the ac will blow

How would I be able to test this to determine if it's bad? Can I run some sort of jumper on this?

[chituntang]

Do you notice your AC turns itself when you have your car running? I notice my system will turn itself off if the AC condenser is not cool enough.

But in your case, how did you recharge your system? Which system did you use (the cheap ~$30 bottle or the one with 2 gauges)? Did you charge up your system after the engine warms up and when AC is running?

But if you need help, we may be able to meet up or something...

[S14DB]

Man, is it hot without an AC working. I've tried searching several times on this and other 240 forums. Even tried googling the issue. I've got a 96' 240sx SE.

My AC blows out cold air in the morning and at night only(would seem it works only when it's 80 degrees and below). However, when the temps are in the 90's and up, the AC blows out hot air. What I found weird was when I opened both sides of the windows during the hot temps outside, the AC system would become cool for just a couple of minutes. Kind of weird, wondering if there is a temp sensor inside the car. The clutch on the compressor clutch comes on when the AC button is pressed and off when depressed. I can also feel the relay under the hood for the clutch click/move when the ac clutch is in-gauging. I filled it up with a can of freon and still no fix. I also tried a can of AC oil and some uv dye to detect for a leak for the past couple of weeks. Keep in mind, I used a gauge to messure how much pressure is on the high and low side, just to be within factory spec. I have the FSM and checking through all the diagnostics. I do have a few questions about some parts and what they do. Any help from the AC experts would be greatly appreciated.

There is a triple-pressure switch on the liquid tank. I'm not sure if this tells the AC system to activate.

Also, there is an Ambient Temperature Switch in between the front bumper and condensor. What does that do? Does it have anything related to cutting the system on/off?
You are using a Dual gauge with high and low pressure? going through the tests in the fsm?

[AutoXsi]

You are using a Dual gauge with high and low pressure? going through the tests in the fsm?

Yes, a dual gauge. I'm trying my best to follow the Nissan 240 Service Manual aka fsm(black thick manual).

[AutoXsi]

Do you notice your AC turns itself when you have your car running? I notice my system will turn itself off if the AC condenser is not cool enough.

But in your case, how did you recharge your system? Which system did you use (the cheap ~$30 bottle or the one with 2 gauges)? Did you charge up your system after the engine warms up and when AC is running?

But if you need help, we may be able to meet up or something...

I had the system warmed up before recharging. 2 gauges btw.

[S14DB]

Yes, a dual gauge. I'm trying my best to follow the Nissan 240 Service Manual aka fsm(black thick manual).

What were the results of Preliminary Check 2?

[AutoXsi]

What were the results of Preliminary Check 2?

Everything else in the "1" section/order is good besides this. Only thing I'm not sure is with the "Magnet clutch does not engage in DEF mode". What is DEF mode?

[S14DB]

Defrost .

[AutoXsi]

It kicks in on Defrost also.

[modulation]

I think you should check the AC condenser fan.
There is a little fan that cools the condenser and if the condenser is too hot I don't think the car will activate the compressor.

It sort of makes sense too since early/late the condenser would be cool enough to not need the fan (hence it works) but then doesn't work when it's hot outside.

Just a though.

[projectRDM]

I think you should check the AC condenser fan.
There is a little fan that cools the condenser and if the condenser is too hot I don't think the car will activate the compressor.

It sort of makes sense too since early/late the condenser would be cool enough to not need the fan (hence it works) but then doesn't work when it's hot outside.

Just a though.

Quit 'thinking'. The compressor is triggered via the ECU, with inputs from the triple pressure switch, the ambient air temperature sensor, and the thermo control amplifier. The condensor doesn't have anything to measure temp, nor can it signal the ECU.

As far as the compressor cycling, all AC compressors cycle at lower fan speeds, there's no need to run full time if you're only using a small amount of air.

[modulation]

Quit 'thinking'. The compressor is triggered via the ECU, with inputs from the triple pressure switch, the ambient air temperature sensor, and the thermo control amplifier. The condensor doesn't have anything to measure temp, nor can it signal the ECU.

As far as the compressor cycling, all AC compressors cycle at lower fan speeds, there's no need to run full time if you're only using a small amount of air.

When the condenser fan doesn't work, the condenser gets too hot and the pressure rises in the entire system including the the compressor. The ECU sees that the pressure is too high in the compressor (with the pressure sensor mentioned above) and turns off the compressor. The fan I am talking about has nothing to do with the blower fan. It's a small fan mounted on the condenser that is mounted on your radiator.

That was very rude of you, there is no reason for the first line at all.
You're talking about a compressor, I was talking about a condenser. They are different. I also never said anything about the condensor signaling the ecu. Stop putting words in my mouth. By "the car" I did infact mean the ECU but there was no reason to be that exact for the sake of this conversation.

No wonder your post count is so high. You didn't even answer the dudes questions, you just jumped in, made an asshole comment and then didn't help anyone. I think you should apologize to me. Why the hate dude?

[Ruby240]

Because he knows WTF he is talking about.

I'm also curious as to why my compressor isn't kicking on. Full charge in the system. I know the compressor works, as I've jumped it at the Triple Pressure Switch pigtail. I've had 3 different TPS's in there and it's still not kicked in. I'm wondering if the Ambient Temp Sensor has a bad ground, and not sending any signal to the ECU telling it to turn on. I haven't checked the Thermo Control Amp yet though.